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Corradi Z, Dhaenens CM, Grunewald O, Kocabaş IS, Meunier I, Banfi S, Karali M, Cremers FPM, Hitti-Malin RJ. Novel and Recurrent Copy Number Variants in ABCA4-Associated Retinopathy. Int J Mol Sci 2024; 25:5940. [PMID: 38892127 PMCID: PMC11173210 DOI: 10.3390/ijms25115940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 05/22/2024] [Accepted: 05/24/2024] [Indexed: 06/21/2024] Open
Abstract
ABCA4 is the most frequently mutated gene leading to inherited retinal disease (IRD) with over 2200 pathogenic variants reported to date. Of these, ~1% are copy number variants (CNVs) involving the deletion or duplication of genomic regions, typically >50 nucleotides in length. An in-depth assessment of the current literature based on the public database LOVD, regarding the presence of known CNVs and structural variants in ABCA4, and additional sequencing analysis of ABCA4 using single-molecule Molecular Inversion Probes (smMIPs) for 148 probands highlighted recurrent and novel CNVs associated with ABCA4-associated retinopathies. An analysis of the coverage depth in the sequencing data led to the identification of eleven deletions (six novel and five recurrent), three duplications (one novel and two recurrent) and one complex CNV. Of particular interest was the identification of a complex defect, i.e., a 15.3 kb duplicated segment encompassing exon 31 through intron 41 that was inserted at the junction of a downstream 2.7 kb deletion encompassing intron 44 through intron 47. In addition, we identified a 7.0 kb tandem duplication of intron 1 in three cases. The identification of CNVs in ABCA4 can provide patients and their families with a genetic diagnosis whilst expanding our understanding of the complexity of diseases caused by ABCA4 variants.
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Affiliation(s)
- Zelia Corradi
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Claire-Marie Dhaenens
- Université de Lille, Inserm, CHU Lille, U1172-LilNCog-Lille Neuroscience & Cognition, F-59000 Lille, France
| | - Olivier Grunewald
- Université de Lille, Inserm, CHU Lille, U1172-LilNCog-Lille Neuroscience & Cognition, F-59000 Lille, France
| | - Ipek Selen Kocabaş
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Isabelle Meunier
- Institute des Neurosciences de Montpellier, INSERM, Université de Montpellier, F-34295 Montpellier, France
| | - Sandro Banfi
- Department of Precision Medicine, University of Campania “Luigi Vanvitelli”, 81031 Naples, Italy
- Telethon Institute of Genetics and Medicine (TIGEM), 80078 Pozzuoli, Italy
| | - Marianthi Karali
- Department of Precision Medicine, University of Campania “Luigi Vanvitelli”, 81031 Naples, Italy
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, University of Campania “Luigi Vanvitelli”, 81031 Naples, Italy
| | - Frans P. M. Cremers
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Rebekkah J. Hitti-Malin
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
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2
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Konečná K, Zapletalová P, Freiberger T, Tichý L. LDLR gene rearrangements in Czech FH patients likely arise from one mutational event. Lipids Health Dis 2024; 23:36. [PMID: 38308247 PMCID: PMC10835926 DOI: 10.1186/s12944-024-02013-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 01/09/2024] [Indexed: 02/04/2024] Open
Abstract
BACKGROUND Large deletions and duplications within the low-density lipoprotein receptor (LDLR) gene make up approximately 10% of LDLR pathogenic variants found in Czech patients with familial hypercholesterolemia. The goal of this study was to test the hypothesis that all probands with each rearrangement share identical breakpoints inherited from a common ancestor and to determine the role of Alu repetitive elements in the generation of these rearrangements. METHODS The breakpoint sequence was determined by PCR amplification and Sanger sequencing. To confirm the breakpoint position, an NGS analysis was performed. Haplotype analysis of common LDLR variants was performed using PCR and Sanger sequencing. RESULTS The breakpoints of 8 rearrangements within the LDLR gene were analysed, including the four most common LDLR rearrangements in the Czech population (number of probands ranging from 8 to 28), and four less common rearrangements (1-4 probands). Probands with a specific rearrangement shared identical breakpoint positions and haplotypes associated with the rearrangement, suggesting a shared origin from a common ancestor. All breakpoints except for one were located inside an Alu element. In 6 out of 8 breakpoints, there was high homology (≥ 70%) between the two Alu repeats in which the break occurred. CONCLUSIONS The most common rearrangements of the LDLR gene in the Czech population likely arose from one mutational event. Alu elements likely played a role in the generation of the majority of rearrangements inside the LDLR gene.
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Affiliation(s)
- Kateřina Konečná
- Centre of Molecular Biology and Genetics, University Hospital Brno, Jihlavská 20, Brno, 625 00, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, Brno, 625 00, Czech Republic
- Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Petra Zapletalová
- Centre of Molecular Biology and Genetics, University Hospital Brno, Jihlavská 20, Brno, 625 00, Czech Republic
| | - Tomáš Freiberger
- Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Centre for Cardiovascular Surgery and Transplantation, Pekařská 53, 656 91, Brno, Czech Republic
| | - Lukáš Tichý
- Centre of Molecular Biology and Genetics, University Hospital Brno, Jihlavská 20, Brno, 625 00, Czech Republic.
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Sakamoto M, Kurosawa K, Tanoue K, Iwama K, Ishida F, Watanabe Y, Okamoto N, Tsuchida N, Uchiyama Y, Koshimizu E, Fujita A, Misawa K, Miyatake S, Mizuguchi T, Matsumoto N. A heterozygous germline deletion within USP8 causes severe neurodevelopmental delay with multiorgan abnormalities. J Hum Genet 2024; 69:85-90. [PMID: 38030753 DOI: 10.1038/s10038-023-01209-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/14/2023] [Accepted: 11/14/2023] [Indexed: 12/01/2023]
Abstract
Ubiquitin-specific protease 8 (USP8) is a deubiquitinating enzyme involved in deubiquitinating the enhanced epidermal growth factor receptor for escape from degradation. Somatic variants at a hotspot in USP8 are a cause of Cushing's disease, and a de novo germline USP8 variant at this hotspot has been described only once previously, in a girl with Cushing's disease and developmental delay. In this study, we investigated an exome-negative patient with severe developmental delay, dysmorphic features, and multiorgan dysfunction by long-read sequencing, and identified a 22-kb de novo germline deletion within USP8 (chr15:50469966-50491995 [GRCh38]). The deletion involved the variant hotspot, one rhodanese domain, and two SH3 binding motifs, and was presumed to be generated through nonallelic homologous recombination through Alu elements. Thus, the patient may have perturbation of the endosomal sorting system and mitochondrial autophagy through the USP8 defect. This is the second reported case of a germline variant in USP8.
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Affiliation(s)
- Masamune Sakamoto
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
- Department of Pediatrics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
- Department of Rare Disease Genomics, Yokohama City University Hospital, Yokohama, Japan
| | - Kenji Kurosawa
- Division of Medical Genetics, Kanagawa Children's Medical Center, Yokohama, Japan
| | - Koji Tanoue
- Department of General Medicine, Kanagawa Children's Medical Center, Yokohama, Japan
| | - Kazuhiro Iwama
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
- Perinatal Center for Maternity and Neonate, Yokohama City University Medical Center, Yokohama, Japan
| | - Fumihiko Ishida
- Perinatal Center for Maternity and Neonate, Yokohama City University Medical Center, Yokohama, Japan
| | - Yoshihiro Watanabe
- Children's Medical Center, Yokohama City University Medical Center, Yokohama, Japan
| | - Nobuhiko Okamoto
- Department of Medical Genetics, Osaka Women's and Children's Hospital, Izumi, Japan
| | - Naomi Tsuchida
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
- Department of Rare Disease Genomics, Yokohama City University Hospital, Yokohama, Japan
| | - Yuri Uchiyama
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
- Department of Rare Disease Genomics, Yokohama City University Hospital, Yokohama, Japan
| | - Eriko Koshimizu
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Atsushi Fujita
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Kazuharu Misawa
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
- Riken Center for Advanced Intelligence Project, Tokyo, Japan
| | - Satoko Miyatake
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
- Department of Clinical Genetics, Yokohama City University Hospital, Yokohama, Japan
| | - Takeshi Mizuguchi
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama, Japan.
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A study of transposable element-associated structural variations (TASVs) using a de novo-assembled Korean genome. Exp Mol Med 2021; 53:615-630. [PMID: 33833373 PMCID: PMC8102501 DOI: 10.1038/s12276-021-00586-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 12/13/2022] Open
Abstract
Advances in next-generation sequencing (NGS) technology have made personal genome sequencing possible, and indeed, many individual human genomes have now been sequenced. Comparisons of these individual genomes have revealed substantial genomic differences between human populations as well as between individuals from closely related ethnic groups. Transposable elements (TEs) are known to be one of the major sources of these variations and act through various mechanisms, including de novo insertion, insertion-mediated deletion, and TE–TE recombination-mediated deletion. In this study, we carried out de novo whole-genome sequencing of one Korean individual (KPGP9) via multiple insert-size libraries. The de novo whole-genome assembly resulted in 31,305 scaffolds with a scaffold N50 size of 13.23 Mb. Furthermore, through computational data analysis and experimental verification, we revealed that 182 TE-associated structural variation (TASV) insertions and 89 TASV deletions contributed 64,232 bp in sequence gain and 82,772 bp in sequence loss, respectively, in the KPGP9 genome relative to the hg19 reference genome. We also verified structural differences associated with TASVs by comparative analysis with TASVs in recent genomes (AK1 and TCGA genomes) and reported their details. Here, we constructed a new Korean de novo whole-genome assembly and provide the first study, to our knowledge, focused on the identification of TASVs in an individual Korean genome. Our findings again highlight the role of TEs as a major driver of structural variations in human individual genomes. A novel strategy for genome analysis offers insights into the distribution and impact on genome variation of transposable elements, DNA sequences that can replicate and relocate themselves at different chromosomal regions. These sequences, also known as ‘jumping genes’, comprise up to 50% of the genome, but it has proven challenging to map them with existing techniques. Seyoung Mun of Dankook University, Cheonan, South Korea, and coworkers have developed a sequencing and computational analysis strategy that allowed them to accurately map transposable elements across the genome of a Korean individual. These data revealed hundreds of insertion and deletion events relative to an existing reference map of the genome, showing significant alterations in the chromosomal structure. The authors speculate that such widespread transposition events could potentially contribute to individual differences in gene expression and risk of disease.
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Bravo JI, Nozownik S, Danthi PS, Benayoun BA. Transposable elements, circular RNAs and mitochondrial transcription in age-related genomic regulation. Development 2020; 147:dev175786. [PMID: 32527937 PMCID: PMC10680986 DOI: 10.1242/dev.175786] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Our understanding of the molecular regulation of aging and age-related diseases is still in its infancy, requiring in-depth characterization of the molecular landscape shaping these complex phenotypes. Emerging classes of molecules with promise as aging modulators include transposable elements, circRNAs and the mitochondrial transcriptome. Analytical complexity means that these molecules are often overlooked, even though they exhibit strong associations with aging and, in some cases, may directly contribute to its progress. Here, we review the links between these novel factors and age-related phenotypes, and we suggest tools that can be easily incorporated into existing pipelines to better understand the aging process.
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Affiliation(s)
- Juan I Bravo
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA
- Graduate Program in the Biology of Aging, University of Southern California, Los Angeles, CA 90089, USA
| | - Séverine Nozownik
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA
- Magistère européen de Génétique, Université Paris Diderot-Paris 7, Paris 75014, France
| | - Prakroothi S Danthi
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA
| | - Bérénice A Benayoun
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA 90089, USA
- USC Norris Comprehensive Cancer Center, Epigenetics and Gene Regulation, Los Angeles, CA 90089, USA
- USC Stem Cell Initiative, Los Angeles, CA 90089, USA
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6
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Structural variation and its potential impact on genome instability: Novel discoveries in the EGFR landscape by long-read sequencing. PLoS One 2020; 15:e0226340. [PMID: 31940362 PMCID: PMC6961855 DOI: 10.1371/journal.pone.0226340] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 11/25/2019] [Indexed: 12/29/2022] Open
Abstract
Structural variation (SV) is typically defined as variation within the human genome that exceeds 50 base pairs (bp). SV may be copy number neutral or it may involve duplications, deletions, and complex rearrangements. Recent studies have shown SV to be associated with many human diseases. However, studies of SV have been challenging due to technological constraints. With the advent of third generation (long-read) sequencing technology, exploration of longer stretches of DNA not easily examined previously has been made possible. In the present study, we utilized third generation (long-read) sequencing techniques to examine SV in the EGFR landscape of four haplotypes derived from two human samples. We analyzed the EGFR gene and its landscape (+/- 500,000 base pairs) using this approach and were able to identify a region of non-coding DNA with over 90% similarity to the most common activating EGFR mutation in non-small cell lung cancer. Based on previously published Alu-element genome instability algorithms, we propose a molecular mechanism to explain how this non-coding region of DNA may be interacting with and impacting the stability of the EGFR gene and potentially generating this cancer-driver gene. By these techniques, we were also able to identify previously hidden structural variation in the four haplotypes and in the human reference genome (hg38). We applied previously published algorithms to compare the relative stabilities of these five different EGFR gene landscape haplotypes to estimate their relative potentials to generate the EGFR exon 19, 15 bp canonical deletion. To our knowledge, the present study is the first to use the differences in genomic architecture between targeted cancer-linked phased haplotypes to estimate their relative potentials to form a common cancer-linked driver mutation.
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Guerrero-Bosagna C. From epigenotype to new genotypes: Relevance of epigenetic mechanisms in the emergence of genomic evolutionary novelty. Semin Cell Dev Biol 2020; 97:86-92. [DOI: 10.1016/j.semcdb.2019.07.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 07/08/2019] [Accepted: 07/08/2019] [Indexed: 11/24/2022]
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8
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Wang H, Tong Z, Li J, Xiao K, Ren F, Xie L. Genetic variants in Forkhead box O1 associated with predisposition to sepsis in a Chinese Han population. BMC Infect Dis 2019; 19:781. [PMID: 31492105 PMCID: PMC6731606 DOI: 10.1186/s12879-019-4330-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 07/29/2019] [Indexed: 12/02/2022] Open
Abstract
Background Genetic variant is one of the causes of sepsis patients’ mortality. Now, many studies have identified several SNPs related to sepsis. However, none of these studies were identified in a genome-wide way. We aimed to detect genetic polymorphisms of sepsis patients. Methods The blood samples of eight normal controls and ten sepsis patients were collected for whole exome sequencing. Then, Single Nucleotide Polymorphisms (SNPs) were selected according to quality score and number of sepsis patients who had this variants. Synonymous mutations were removed. Genes including these remaining variants were used for functional analyses. After analyses, the remaining SNPs and indels were validated in 149 normal controls and 156 sepsis patients. Finally, serum levels of proteins coded by genes including these SNPs were evaluated. Results After whole exome sequencing, 97 SNPs and one indel site were left. Then, functional screening was performed. Only seven SNPs were used for further validation. As a result, the rs2721068 in dominant model and rs17446614 in recessive model were associated with sepsis, and the ORs of these two SNPs were 3.24 (95%CI, 1.25, 8.44) and 0.47 (0.026, 0.88), respectively. These two SNPs were both located in Forkhead box O1 (FOXO1) gene. For rs2721068 (T/T, T/C-C/C) and rs17446614 (A/A-A/G, G/G), serum levels of foxo1 in sepsis patients were both significantly lower in normal controls. Conclusions We firstly reported that the rs2721068 and rs17446614 were correlated to genetic predisposition to sepsis. Electronic supplementary material The online version of this article (10.1186/s12879-019-4330-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Huijuan Wang
- Department of Respiratory Medicine, Chinese PLA General Hospital, 28th Fuxing Road, Beijing, 100853, China.,Department of Respiratory and Critical Care Medicine, Beijing Chao-Yang Hospital, Beijing Institute of Respiratory Medicine, Capital Medical University, Beijing, 100020, China
| | - Zhaohui Tong
- Department of Respiratory and Critical Care Medicine, Beijing Chao-Yang Hospital, Beijing Institute of Respiratory Medicine, Capital Medical University, Beijing, 100020, China
| | - Jia Li
- Department of Nanlou Respiratory Medicine, Chinese PLA General Hospital, 28th Fuxing Road, Beijing, 100853, China
| | - Kun Xiao
- Department of Respiratory Medicine, Chinese PLA General Hospital, 28th Fuxing Road, Beijing, 100853, China
| | - Feifei Ren
- Department of Respiratory Medicine, Chinese PLA General Hospital, 28th Fuxing Road, Beijing, 100853, China
| | - Lixin Xie
- Department of Respiratory Medicine, Chinese PLA General Hospital, 28th Fuxing Road, Beijing, 100853, China.
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9
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Casanova EL, Switala AE, Dandamudi S, Hickman AR, Vandenbrink J, Sharp JL, Feltus FA, Casanova MF. Autism risk genes are evolutionarily ancient and maintain a unique feature landscape that echoes their function. Autism Res 2019; 12:860-869. [PMID: 31025836 PMCID: PMC6613973 DOI: 10.1002/aur.2112] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 03/22/2019] [Accepted: 04/06/2019] [Indexed: 11/09/2022]
Abstract
Previous research on autism risk (ASD), developmental regulatory (DevReg), and central nervous system (CNS) genes suggests they tend to be large in size, enriched in nested repeats, and mutation intolerant. The relevance of these genomic features is intriguing yet poorly understood. In this study, we investigated the feature landscape of these gene groups to discover structural themes useful in interpreting their function, developmental patterns, and evolutionary history. ASD, DevReg, CNS, housekeeping, and whole genome control (WGC) groups were compiled using various resources. Multiple gene features of interest were extracted from NCBI/UCSC Bioinformatics. Residual variation intolerance scores, Exome Aggregation Consortium pLI scores, and copy number variation data from Decipher were used to estimate variation intolerance. Gene age and protein-protein interactions (PPI) were estimated using Ensembl and EBI Intact databases, respectively. Compared to WGC: ASD, DevReg, and CNS genes are longer, produce larger proteins, maintain greater numbers/density of conserved noncoding elements and transposable elements, produce more transcript variants, and are comparatively variation intolerant. After controlling for gene size, mutation tolerance, and clinical association, ASD genes still retain many of these same features. In addition, we also found that ASD genes that are extremely mutation intolerant have larger PPI networks. These data support many of the recent findings within the field of autism genetics but also expand our understanding of the evolution of these broad gene groups, their potential regulatory complexity, and the extent to which they interact with the cellular network. Autism Res 2019, 12: 860-869. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Autism risk genes are more ancient compared to other genes in the genome. As such, they exhibit physical features related to their age, including long gene and protein size and regulatory sequences that help to control gene expression. They share many of these same features with other genes that are expressed in the brain and/or are associated with prenatal development.
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Affiliation(s)
- Emily L. Casanova
- Department of Biomedical Sciences, University of South
Carolina, South Carolina, USA
- Department of Pediatrics, Greenville Health System,
Greenville, USA
| | - Andrew E. Switala
- Department of Bioengineering, University of Louisville,
Louisville, Kentucky, USA
| | - Srini Dandamudi
- Department of Statistics, Colorado State University, Fort
Collins, Colorado, USA
| | - Allison R. Hickman
- Department of Genetics and Biochemistry, Clemson
University, Clemson, South Carolina, USA
| | | | - Julia L. Sharp
- Department of Statistics, Colorado State University, Fort
Collins, Colorado, USA
| | - F. Alex Feltus
- Department of Genetics and Biochemistry, Clemson
University, Clemson, South Carolina, USA
| | - Manuel F. Casanova
- Department of Biomedical Sciences, University of South
Carolina, South Carolina, USA
- Department of Pediatrics, Greenville Health System,
Greenville, USA
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10
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Vidotto T, Tiezzi DG, Squire JA. Distinct subtypes of genomic PTEN deletion size influence the landscape of aneuploidy and outcome in prostate cancer. Mol Cytogenet 2018; 11:1. [PMID: 29308088 PMCID: PMC5753467 DOI: 10.1186/s13039-017-0348-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 12/01/2017] [Indexed: 12/16/2022] Open
Abstract
Background Inactivation of the PTEN tumor suppressor gene by deletion occurs in 20-30% of prostate cancer tumors and loss strongly correlates with a worse outcome. PTEN loss of function not only leads to activation of the PI3K/AKT pathway, but is also thought to affect genome stability and increase levels of tumor aneuploidy. We performed an in silico integrative genomic and transcriptomic analysis of 491 TCGA prostate cancer tumors. These data were used to map the genomic sizes of PTEN gene deletions and to characterize levels of instability and patterns of aneuploidy acquisition. Results PTEN homozygous deletions had a significant increase in aneuploidy compared to PTEN tumors without an apparent deletion, and hemizygous deletions showed an intermediate aneuploidy profile. A supervised clustering of somatic copy number alterations (SCNA) demonstrated that the size of PTEN deletions was not random, but comprised five distinct subtypes: (1) "Small Interstitial" (70 bp-789Kb); (2) "Large Interstitial" (1-7 MB); (3) "Large Proximal" (3-65 MB); (4) "Large Terminal" (8-64 MB), and (5) "Extensive" (71-132 MB). Many of the deleted fragments in each subtype were flanked by low copy repetitive (LCR) sequences. SCNAs such as gain at 3q21.1-3q29 and deletions at 8p, RB1, TP53 and TMPRSS2-ERG were variably present in all subtypes. Other SCNAs appeared to be recurrent in some deletion subtypes, but absent from others. To determine how the aneuploidy influenced global levels of gene expression, we performed a comparative transcriptome analysis. One deletion subtype (Large Interstitial) was characterized by gene expression changes associated with angiogenesis and cell adhesion, structure, and metabolism. Logistic regression demonstrated that this deletion subtype was associated with a high Gleason score (HR = 2.386; 95% C.I. 1.245-4.572), extraprostatic extension (HR = 2.423, 95% C.I. 1.157-5.075), and metastasis (HR = 7.135; 95% C.I. 1.540-33.044). Univariate and multivariate Cox Regression showed that presence of this deletion subtype was also strongly predictive of disease recurrence. Conclusions Our findings indicate that genomic deletions of PTEN fall into five different size distributions, with breakpoints that often occur close LCR regions, and that each subtype is associated with a characteristic aneuploidy signature. The Large Interstitial deletion had a distinct gene expression signature that was related to cancer progression and was also predictive of a worse prognosis.
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Affiliation(s)
- Thiago Vidotto
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Daniel Guimarães Tiezzi
- Deparment of Gynecology and Obstetrics, Clinical Hospital of Ribeirão Preto, Ribeirão Preto, Brazil
| | - Jeremy A Squire
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil.,Department of Pathology and Legal Medicine, Ribeirão Preto Medical School, University of São Paulo, 3900 Bandeirantes Avenue, Monte Alegre, Ribeirão Preto, São Paulo 14040-900 Brazil.,Department of Pathology and Molecular Medicine, Queen's University, Kingston, Canada
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11
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Suarez NA, Macia A, Muotri AR. LINE-1 retrotransposons in healthy and diseased human brain. Dev Neurobiol 2017; 78:434-455. [PMID: 29239145 DOI: 10.1002/dneu.22567] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 12/07/2017] [Accepted: 12/08/2017] [Indexed: 12/12/2022]
Abstract
Long interspersed element-1 (LINE-1 or L1) is a transposable element with the ability to self-mobilize throughout the human genome. The L1 elements found in the human brain is hypothesized to date back 56 million years ago and has survived evolution, currently accounting for 17% of the human genome. L1 retrotransposition has been theorized to contribute to somatic mosaicism. This review focuses on the presence of L1 in the healthy and diseased human brain, such as in autism spectrum disorders. Throughout this exploration, we will discuss the impact L1 has on neurological disorders that can occur throughout the human lifetime. With this, we hope to better understand the complex role of L1 in the human brain development and its implications to human cognition. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 434-455, 2018.
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Affiliation(s)
- Nicole A Suarez
- Department of Pediatrics/Rady Children's Hospital San Diego, University of California San Diego, La Jolla, California, 92093
| | - Angela Macia
- Department of Pediatrics/Rady Children's Hospital San Diego, University of California San Diego, La Jolla, California, 92093
| | - Alysson R Muotri
- Department of Pediatrics/Rady Children's Hospital San Diego, University of California San Diego, La Jolla, California, 92093
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12
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Hamilton WL, Claessens A, Otto TD, Kekre M, Fairhurst RM, Rayner JC, Kwiatkowski D. Extreme mutation bias and high AT content in Plasmodium falciparum. Nucleic Acids Res 2017; 45:1889-1901. [PMID: 27994033 PMCID: PMC5389722 DOI: 10.1093/nar/gkw1259] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 12/01/2016] [Indexed: 01/31/2023] Open
Abstract
For reasons that remain unknown, the Plasmodium falciparum genome has an exceptionally high AT content compared to other Plasmodium species and eukaryotes in general - nearly 80% in coding regions and approaching 90% in non-coding regions. Here, we examine how this phenomenon relates to genome-wide patterns of de novo mutation. Mutation accumulation experiments were performed by sequential cloning of six P. falciparum isolates growing in human erythrocytes in vitro for 4 years, with 279 clones sampled for whole genome sequencing at different time points. Genome sequence analysis of these samples revealed a significant excess of G:C to A:T transitions compared to other types of nucleotide substitution, which would naturally cause AT content to equilibrate close to the level seen across the P. falciparum reference genome (80.6% AT). These data also uncover an extremely high rate of small indel mutation relative to other species, primarily associated with repetitive AT-rich sequences, in addition to larger-scale structural rearrangements focused in antigen-coding var genes. In conclusion, high AT content in P. falciparum is driven by a systematic mutational bias and ultimately leads to an unusual level of microstructural plasticity, raising the question of whether this contributes to adaptive evolution.
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Affiliation(s)
- William L Hamilton
- Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK.,University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0SP, UK
| | - Antoine Claessens
- Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK.,Medical Research Council Unit The Gambia, Atlantic Road, Fajara, P.O. Box 273, Banjul, The Gambia.,Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Thomas D Otto
- Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK
| | - Mihir Kekre
- Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK
| | - Rick M Fairhurst
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Julian C Rayner
- Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK
| | - Dominic Kwiatkowski
- Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK.,Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
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13
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Analysis of RP2 and RPGR Mutations in Five X-Linked Chinese Families with Retinitis Pigmentosa. Sci Rep 2017; 7:44465. [PMID: 28294154 PMCID: PMC5353642 DOI: 10.1038/srep44465] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 02/08/2017] [Indexed: 11/08/2022] Open
Abstract
Mutations in RP2 and RPGR genes are responsible for the X-linked retinitis pigmentosa (XLRP). In this study, we analyzed the RP2 and RPGR gene mutations in five Han Chinese families with XLRP. An approximately 17Kb large deletion including the exon 4 and exon 5 of RP2 gene was found in an XLRP family. In addition, four frameshift mutations including three novel mutations of c.1059 + 1 G > T, c.2002dupC and c.2236_2237del CT, as well as a previously reported mutation of c.2899delG were detected in the RPGR gene in the other four families. Our study further expands the mutation spectrum of RP2 and RPGR, and will be helpful for further study molecular pathogenesis of XLRP.
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14
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15
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Morales ME, Derbes RS, Ade CM, Ortego JC, Stark J, Deininger PL, Roy-Engel AM. Heavy Metal Exposure Influences Double Strand Break DNA Repair Outcomes. PLoS One 2016. [PMID: 26966913 DOI: 10.1371/journal.pone.0151367]] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Heavy metals such as cadmium, arsenic and nickel are classified as carcinogens. Although the precise mechanism of carcinogenesis is undefined, heavy metal exposure can contribute to genetic damage by inducing double strand breaks (DSBs) as well as inhibiting critical proteins from different DNA repair pathways. Here we take advantage of two previously published culture assay systems developed to address mechanistic aspects of DNA repair to evaluate the effects of heavy metal exposures on competing DNA repair outcomes. Our results demonstrate that exposure to heavy metals significantly alters how cells repair double strand breaks. The effects observed are both specific to the particular metal and dose dependent. Low doses of NiCl2 favored resolution of DSBs through homologous recombination (HR) and single strand annealing (SSA), which were inhibited by higher NiCl2 doses. In contrast, cells exposed to arsenic trioxide preferentially repaired using the "error prone" non-homologous end joining (alt-NHEJ) while inhibiting repair by HR. In addition, we determined that low doses of nickel and cadmium contributed to an increase in mutagenic recombination-mediated by Alu elements, the most numerous family of repetitive elements in humans. Sequence verification confirmed that the majority of the genetic deletions were the result of Alu-mediated non-allelic recombination events that predominantly arose from repair by SSA. All heavy metals showed a shift in the outcomes of alt-NHEJ repair with a significant increase of non-templated sequence insertions at the DSB repair site. Our data suggest that exposure to heavy metals will alter the choice of DNA repair pathway changing the genetic outcome of DSBs repair.
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Affiliation(s)
- Maria E Morales
- Department of Epidemiology and Tulane Cancer Center, and Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112, United States of America
| | - Rebecca S Derbes
- Department of Epidemiology and Tulane Cancer Center, and Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112, United States of America
| | - Catherine M Ade
- Department of Cellular and Molecular Biology, Tulane University, 6400 Freret Street, New Orleans, LA 70118, United States of America
| | - Jonathan C Ortego
- Department of Epidemiology and Tulane Cancer Center, and Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112, United States of America
| | - Jeremy Stark
- Department of Radiation Biology, Beckman Research Institute of the City of Hope, 1500 E Duarte Rd., Duarte, CA 91010, United States of America
| | - Prescott L Deininger
- Department of Epidemiology and Tulane Cancer Center, and Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112, United States of America
| | - Astrid M Roy-Engel
- Department of Epidemiology and Tulane Cancer Center, and Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112, United States of America
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16
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Morales ME, Derbes RS, Ade CM, Ortego JC, Stark J, Deininger PL, Roy-Engel AM. Heavy Metal Exposure Influences Double Strand Break DNA Repair Outcomes. PLoS One 2016; 11:e0151367. [PMID: 26966913 PMCID: PMC4788447 DOI: 10.1371/journal.pone.0151367] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 02/26/2016] [Indexed: 11/22/2022] Open
Abstract
Heavy metals such as cadmium, arsenic and nickel are classified as carcinogens. Although the precise mechanism of carcinogenesis is undefined, heavy metal exposure can contribute to genetic damage by inducing double strand breaks (DSBs) as well as inhibiting critical proteins from different DNA repair pathways. Here we take advantage of two previously published culture assay systems developed to address mechanistic aspects of DNA repair to evaluate the effects of heavy metal exposures on competing DNA repair outcomes. Our results demonstrate that exposure to heavy metals significantly alters how cells repair double strand breaks. The effects observed are both specific to the particular metal and dose dependent. Low doses of NiCl2 favored resolution of DSBs through homologous recombination (HR) and single strand annealing (SSA), which were inhibited by higher NiCl2 doses. In contrast, cells exposed to arsenic trioxide preferentially repaired using the “error prone” non-homologous end joining (alt-NHEJ) while inhibiting repair by HR. In addition, we determined that low doses of nickel and cadmium contributed to an increase in mutagenic recombination-mediated by Alu elements, the most numerous family of repetitive elements in humans. Sequence verification confirmed that the majority of the genetic deletions were the result of Alu-mediated non-allelic recombination events that predominantly arose from repair by SSA. All heavy metals showed a shift in the outcomes of alt-NHEJ repair with a significant increase of non-templated sequence insertions at the DSB repair site. Our data suggest that exposure to heavy metals will alter the choice of DNA repair pathway changing the genetic outcome of DSBs repair.
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Affiliation(s)
- Maria E. Morales
- Department of Epidemiology and Tulane Cancer Center, and Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112, United States of America
| | - Rebecca S. Derbes
- Department of Epidemiology and Tulane Cancer Center, and Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112, United States of America
| | - Catherine M. Ade
- Department of Cellular and Molecular Biology, Tulane University, 6400 Freret Street, New Orleans, LA 70118, United States of America
| | - Jonathan C. Ortego
- Department of Epidemiology and Tulane Cancer Center, and Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112, United States of America
| | - Jeremy Stark
- Department of Radiation Biology, Beckman Research Institute of the City of Hope, 1500 E Duarte Rd., Duarte, CA 91010, United States of America
| | - Prescott L. Deininger
- Department of Epidemiology and Tulane Cancer Center, and Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112, United States of America
| | - Astrid M. Roy-Engel
- Department of Epidemiology and Tulane Cancer Center, and Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112, United States of America
- * E-mail:
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17
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Mehlotra RK, Zimmerman PA, Weinberg A. Defensin gene variation and HIV/AIDS: a comprehensive perspective needed. J Leukoc Biol 2016; 99:687-92. [PMID: 26957215 DOI: 10.1189/jlb.6ru1215-560r] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 02/02/2016] [Indexed: 01/24/2023] Open
Abstract
Both α- and β-defensins have anti-human immunodeficiency virus activity. These defensins achieve human immunodeficiency virus inhibition through a variety of mechanisms, including direct binding with virions, binding to and modulation of host cell-surface receptors with disruption of intracellular signaling, and functioning as chemokines or cytokines to augment and alter adaptive immune responses. Polymorphisms in the defensin genes have been associated with susceptibility to human immunodeficiency virus infection and disease progression. However, the roles that these defensins and their genetic polymorphisms have in influencing human immunodeficiency virus/acquired immunodeficiency syndrome outcomes are not straightforward and, at times, appear contradictory. Differences in populations, study designs, and techniques for genotyping defensin gene polymorphisms may have contributed to this lack of clarity. In addition, a comprehensive approach, where both subfamilies of defensins and their all-inclusive genetic polymorphism profiles are analyzed, is lacking. Such an approach may reveal whether the human immunodeficiency virus inhibitory activities of α- and β-defensins are based on parallel or divergent mechanisms and may provide further insights into how the genetic predisposition for susceptibility or resistance to human immunodeficiency virus/acquired immunodeficiency syndrome is orchestrated between these molecules.
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Affiliation(s)
- Rajeev K Mehlotra
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Peter A Zimmerman
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Aaron Weinberg
- Department of Biological Sciences, Case Western Reserve University School of Dental Medicine, Cleveland, Ohio, USA
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18
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White TB, Morales ME, Deininger PL. Alu elements and DNA double-strand break repair. Mob Genet Elements 2015; 5:81-85. [PMID: 26942043 DOI: 10.1080/2159256x.2015.1093067] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 08/31/2015] [Accepted: 09/04/2015] [Indexed: 12/30/2022] Open
Abstract
Alu elements represent one of the most common sources of homology and homeology in the human genome. Homeologous recombination between Alu elements represents a major form of genetic instability leading to deletions and duplications. Although these types of events have been studied extensively through genomic sequencing to assess the impact of Alu elements on disease mutations and genome evolution, the overall abundance of Alu elements in the genome often makes it difficult to assess the relevance of the Alu elements to specific recombination events. We recently reported a powerful new reporter gene system that allows the assessment of various cis and trans factors on the contribution of Alu elements to various forms of genetic instability. This allowed a quantitative measurement of the influence of mismatches on Alu elements and instability. It also confirmed that homeologous Alu elements are able to stimulate non-homologous end joining events in their vicinity. This appears to be dependent on portions of the mismatch repair pathway. We are now in a position to begin to unravel the complex influences of Alu density, mismatch and location with alterations of DNA repair processes in various tissues and tumors.
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Affiliation(s)
- Travis B White
- Tulane Cancer Center; Tulane University Health Sciences Center ; New Orleans, LA USA
| | - Maria E Morales
- Tulane Cancer Center; Tulane University Health Sciences Center ; New Orleans, LA USA
| | - Prescott L Deininger
- Tulane Cancer Center; Tulane University Health Sciences Center ; New Orleans, LA USA
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19
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Wang MD, Dzama K, Hefer CA, Muchadeyi FC. Genomic population structure and prevalence of copy number variations in South African Nguni cattle. BMC Genomics 2015; 16:894. [PMID: 26531252 PMCID: PMC4632335 DOI: 10.1186/s12864-015-2122-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Accepted: 10/22/2015] [Indexed: 12/21/2022] Open
Abstract
Background Copy number variations (CNVs) are modifications in DNA structure comprising of deletions, duplications, insertions and complex multi-site variants. Although CNVs are proven to be involved in a variety of phenotypic discrepancies, the full extent and consequence of CNVs is yet to be understood. To date, no such genomic characterization has been performed in indigenous South African Nguni cattle. Nguni cattle are recognized for their ability to sustain harsh environmental conditions while exhibiting enhanced resistance to disease and parasites and are thought to comprise of up to nine different ecotypes. Methods Illumina BovineSNP50 Beadchip data was utilized to investigate genomic population structure and the prevalence of CNVs in 492 South African Nguni cattle. PLINK, ADMIXTURE, R, gPLINK and Haploview software was utilized for quality control, population structure and haplotype block determination. PennCNV hidden Markov model identified CNVs and genes contained within and 10 Mb downstream from reported CNVs. PANTHER and Ensembl databases were subsequently utilized for gene annotation analyses. Results Population structure analyses on Nguni cattle revealed 5 sub-populations with a possible sub-structure evident at K equal to 8. Four hundred and thirty three CNVs that formed 334 CNVRs ranging from 30 kb to 1 Mb in size are reported. Only 231 of the 492 animals demonstrated CNVRs. Two hundred and eighty nine genes were observed within CNVRs identified. Of these 149, 28, 44, 2 and 14 genes were unique to sub-populations A, B, C, D and E respectively. Gene ontology analyses demonstrated a number of pathways to be represented by respective genes, including immune response, response to abiotic stress and biological regulation processess. Conclusions CNVs may explain part of the phenotypic diversity and the enhanced adaptation evident in Nguni cattle. Genes involved in a number of cellular components, biological processes and molecular functions are reported within CNVRs identified. The significance of such CNVRs and the possible effect thereof needs to be ascertained and may hold interesting insight into the functional and adaptive consequence of CNVs in cattle. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-2122-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Magretha Diane Wang
- Department of Animal Sciences, University of Stellenbosch, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa. .,Biotechnology Platform, Agricultural Research Council, Private Bag X5, Onderstepoort, 0110, South Africa.
| | - Kennedy Dzama
- Department of Animal Sciences, University of Stellenbosch, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa.
| | - Charles A Hefer
- Biotechnology Platform, Agricultural Research Council, Private Bag X5, Onderstepoort, 0110, South Africa.
| | - Farai C Muchadeyi
- Biotechnology Platform, Agricultural Research Council, Private Bag X5, Onderstepoort, 0110, South Africa.
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20
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Haploinsufficiency and triploinsensitivity of the same 6p25.1p24.3 region in a family. BMC Med Genomics 2015; 8:38. [PMID: 26174853 PMCID: PMC4502905 DOI: 10.1186/s12920-015-0113-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 07/03/2015] [Indexed: 12/29/2022] Open
Abstract
Background Chromosome 6pter-p24 deletion syndrome (OMIM #612582) is a recognized chromosomal disorder. Most of the individuals with this syndrome carry a terminal deletion of the short arm of chromosome 6 (6p) with a breakpoint within the 6p25.3p23 region. An approximately 2.1 Mb terminal region has been reported to be responsible for some major features of the syndrome. The phenotypic contributions of other deleted regions are unknown. Interstitial deletions of the region are uncommon, and reciprocal interstitial duplication in this region is extremely rare. Case presentation We present a family carrying an interstitial deletion and its reciprocal duplication within the 6p25.1p24.3 region. The deletion is 5.6 Mb in size and was detected by array comparative genomic hybridization (aCGH) in a 26-month-old female proband who presented speech delay and mild growth delay, bilateral conductive hearing loss and dysmorphic features. Array CGH studies of her family members detected an apparently mosaic deletion of the same region in the proband’s mildly affected mother, but a reciprocal interstitial duplication in her phenotypically normal brother. Further chromosomal and fluorescence in situ hybridization (FISH) analyses revealed that instead of a simple mosaic deletion of 6p25.1p24.3, the mother actually carries three cell populations in her peripheral blood, including a deletion (~70 %), a duplication (~8 %) and a normal (~22 %) populations. Therefore, both the deletion and duplication seen in the siblings were apparently inherited from the mother. Conclusions Interstitial deletion within the 6p25.1p24.3 region and its reciprocal duplication may co-exist in the same individual and/or family due to mitotic unequal sister chromatid exchange. While the deletion causes phenotypes reportedly associated with the chromosome 6pter-p24 deletion syndrome, the reciprocal duplication may have no or minimal phenotypic effect, suggesting possible triploinsensitivity of the same region. In addition, the cells with the duplication may compensate the phenotypic effect of the cells with the deletion in the same individual as implied by the maternal karyotype and her mild phenotype. Chromosomal and FISH analyses are essential to verify abnormal cytogenomic array findings.
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21
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Landais E, Leroy C, Kleinfinger P, Brunet S, Koubi V, Pietrement C, Poli-Mérol ML, Fiquet C, Souchon PF, Beri M, Jonveaux P, Garnotel R, Gaillard D, Doco-Fenzy M. A pure familial 6q15q21 split duplication associated with obesity and transmitted with partial reduction. Am J Med Genet A 2015; 167:1275-84. [PMID: 25900228 DOI: 10.1002/ajmg.a.36995] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 12/29/2014] [Indexed: 01/06/2023]
Abstract
Familial transmission of chromosome 6 duplications is rare. We report on the first observation of a maternally-inherited pure segmental 6q duplication split into two segments, 6q15q16.3 and 6q16.3q21, and associated with obesity. Obesity has previously been correlated to chromosome 6 q-arm deletion but has not yet been assessed in duplications. The aim of this study was to characterize the structure of these intrachromosomal insertional translocations by classic cytogenetic banding, array-CGH, FISH, M-banding and genotyping using microsatellites and SNP array analysis, in a mother and four offspring. The duplicated 6q segments, 9.75 Mb (dup 1) and 7.05 Mb (dup 2) in size in the mother, were inserted distally into two distinct chromosome 6q regions. They were transmitted to four offspring. A son and a daughter inherited the two unbalanced insertions and displayed, like the mother, an abnormal phenotype with facial dysmorphism, intellectual disability, and morbid obesity. Curiously, two daughters with a normal phenotype inherited only the smaller segment, 6q16.3q21. The abnormal phenotype was associated with the larger proximal 6q15q16.3 duplication. We hypothesize a mechanism for this exceptional phenomenon of recurrent reduction and transmission of the duplication during meiosis in a family. We expect the interpretation of our findings to be useful for genetic counseling and for understanding the mechanisms underlying these large segmental 6q duplications and their evolution.
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Affiliation(s)
- Emilie Landais
- CHU-Reims, HMB, Service de Génétique, France.,CHU-Reims, HMB, Plateforme Régionale de Biologie Innovante, France
| | - Camille Leroy
- CHU-Reims, HMB, Service de Génétique, France.,Université de Reims Champagne-Ardenne, UFR de médecine, France
| | | | | | - Valérie Koubi
- Service de génétique Médicale, Laboratoire de génétique moléculaire, CHU Hopital Necker enfants malades, Paris, France
| | | | - Marie-Laurence Poli-Mérol
- Université de Reims Champagne-Ardenne, UFR de médecine, France.,CHU-Reims, American Memorial Hospital, Service de Chirurgie pédiatrique, France
| | - Caroline Fiquet
- CHU-Reims, American Memorial Hospital, Service de Chirurgie pédiatrique, France.,SFR CAP Santé, Reims, EA 3801, France
| | | | - Mylène Beri
- CHU-Nancy, Laboratoire de Génétique Médicale, Nancy Université, France
| | - Philippe Jonveaux
- CHU-Nancy, Laboratoire de Génétique Médicale, Nancy Université, France
| | - Roselyne Garnotel
- CHU-Reims, Laboratoire de Biochimie Médicale et Biologie Moléculaire, CNRS UMR 6198, UFR, Médecine, France
| | - Dominique Gaillard
- CHU-Reims, HMB, Service de Génétique, France.,Université de Reims Champagne-Ardenne, UFR de médecine, France
| | - Martine Doco-Fenzy
- CHU-Reims, HMB, Service de Génétique, France.,SFR CAP Santé, Reims, EA 3801, France
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22
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Morales ME, White TB, Streva VA, DeFreece CB, Hedges DJ, Deininger PL. The contribution of alu elements to mutagenic DNA double-strand break repair. PLoS Genet 2015; 11:e1005016. [PMID: 25761216 PMCID: PMC4356517 DOI: 10.1371/journal.pgen.1005016] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 01/22/2015] [Indexed: 11/18/2022] Open
Abstract
Alu elements make up the largest family of human mobile elements, numbering 1.1 million copies and comprising 11% of the human genome. As a consequence of evolution and genetic drift, Alu elements of various sequence divergence exist throughout the human genome. Alu/Alu recombination has been shown to cause approximately 0.5% of new human genetic diseases and contribute to extensive genomic structural variation. To begin understanding the molecular mechanisms leading to these rearrangements in mammalian cells, we constructed Alu/Alu recombination reporter cell lines containing Alu elements ranging in sequence divergence from 0%-30% that allow detection of both Alu/Alu recombination and large non-homologous end joining (NHEJ) deletions that range from 1.0 to 1.9 kb in size. Introduction of as little as 0.7% sequence divergence between Alu elements resulted in a significant reduction in recombination, which indicates even small degrees of sequence divergence reduce the efficiency of homology-directed DNA double-strand break (DSB) repair. Further reduction in recombination was observed in a sequence divergence-dependent manner for diverged Alu/Alu recombination constructs with up to 10% sequence divergence. With greater levels of sequence divergence (15%-30%), we observed a significant increase in DSB repair due to a shift from Alu/Alu recombination to variable-length NHEJ which removes sequence between the two Alu elements. This increase in NHEJ deletions depends on the presence of Alu sequence homeology (similar but not identical sequences). Analysis of recombination products revealed that Alu/Alu recombination junctions occur more frequently in the first 100 bp of the Alu element within our reporter assay, just as they do in genomic Alu/Alu recombination events. This is the first extensive study characterizing the influence of Alu element sequence divergence on DNA repair, which will inform predictions regarding the effect of Alu element sequence divergence on both the rate and nature of DNA repair events. DNA double-strand breaks (DSBs) are a highly mutagenic form of DNA damage that can be repaired through one of several pathways with varied degrees of sequence preservation. Faithful repair of DSBs often occurs through gene conversion in which a sister chromatid is used as a repair template. Unfaithful repair of DSBs can occur through non-allelic homologous or homeologous recombination, which leads to chromosomal abnormalities such as deletions, duplications, and translocations and has been shown to cause several human genetic diseases. Substrates for these homologous and homeologous events include Alu elements, which are approximately 300 bp elements that comprise ~11% of the human genome. We use a new reporter assay to show that repair of DSBs results in Alu-mediated deletions that resolve through several distinct repair pathways. Either single-strand annealing (SSA) repair or microhomology-mediated end joining occurs ‘in register’ between two Alu elements when Alu sequence divergence is low. However, with more diverged Alu elements, like those typically found in the human genome, repair of DSBs appears to use the Alu/Alu homeology to direct non-homologous end joining in the general vicinity of the Alu elements. Mutagenic NHEJ repair involving divergent Alu elements may represent a common repair event in primate genomes.
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Affiliation(s)
- Maria E. Morales
- Tulane Cancer Center and Department of Epidemiology, Tulane University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Travis B. White
- Tulane Cancer Center and Department of Epidemiology, Tulane University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Vincent A. Streva
- Tulane Cancer Center and Department of Epidemiology, Tulane University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Cecily B. DeFreece
- Department of Biology, Xavier University of Louisiana, New Orleans, Louisiana, United States of America
| | - Dale J. Hedges
- Division of Human Genetics, Department of Internal Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Prescott L. Deininger
- Tulane Cancer Center and Department of Epidemiology, Tulane University Health Sciences Center, New Orleans, Louisiana, United States of America
- * E-mail:
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23
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Chen L, Zhou W, Zhang L, Zhang F. Genome architecture and its roles in human copy number variation. Genomics Inform 2014; 12:136-44. [PMID: 25705150 PMCID: PMC4330246 DOI: 10.5808/gi.2014.12.4.136] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 11/12/2014] [Accepted: 11/12/2014] [Indexed: 02/06/2023] Open
Abstract
Besides single-nucleotide variants in the human genome, large-scale genomic variants, such as copy number variations (CNVs), are being increasingly discovered as a genetic source of human diversity and the pathogenic factors of diseases. Recent experimental findings have shed light on the links between different genome architectures and CNV mutagenesis. In this review, we summarize various genomic features and discuss their contributions to CNV formation. Genomic repeats, including both low-copy and high-copy repeats, play important roles in CNV instability, which was initially known as DNA recombination events. Furthermore, it has been found that human genomic repeats can also induce DNA replication errors and consequently result in CNV mutations. Some recent studies showed that DNA replication timing, which reflects the high-order information of genomic organization, is involved in human CNV mutations. Our review highlights that genome architecture, from DNA sequence to high-order genomic organization, is an important molecular factor in CNV mutagenesis and human genomic instability.
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Affiliation(s)
- Lu Chen
- School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Weichen Zhou
- School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Ling Zhang
- School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Feng Zhang
- School of Life Sciences, Fudan University, Shanghai 200438, China. ; Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200438, China
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24
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The Alu-rich genomic architecture of SPAST predisposes to diverse and functionally distinct disease-associated CNV alleles. Am J Hum Genet 2014; 95:143-61. [PMID: 25065914 DOI: 10.1016/j.ajhg.2014.06.014] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 06/30/2014] [Indexed: 01/27/2023] Open
Abstract
Intragenic copy-number variants (CNVs) contribute to the allelic spectrum of both Mendelian and complex disorders. Although pathogenic deletions and duplications in SPAST (mutations in which cause autosomal-dominant spastic paraplegia 4 [SPG4]) have been described, their origins and molecular consequences remain obscure. We mapped breakpoint junctions of 54 SPAST CNVs at nucleotide resolution. Diverse combinations of exons are deleted or duplicated, highlighting the importance of particular exons for spastin function. Of the 54 CNVs, 38 (70%) appear to be mediated by an Alu-based mechanism, suggesting that the Alu-rich genomic architecture of SPAST renders this locus susceptible to various genome rearrangements. Analysis of breakpoint Alus further informs a model of Alu-mediated CNV formation characterized by small CNV size and potential involvement of mechanisms other than homologous recombination. Twelve deletions (22%) overlap part of SPAST and a portion of a nearby, directly oriented gene, predicting novel chimeric genes in these subjects' genomes. cDNA from a subject with a SPAST final exon deletion contained multiple SPAST:SLC30A6 fusion transcripts, indicating that SPAST CNVs can have transcriptional effects beyond the gene itself. SLC30A6 has been implicated in Alzheimer disease, so these fusion gene data could explain a report of spastic paraplegia and dementia cosegregating in a family with deletion of the final exon of SPAST. Our findings provide evidence that the Alu genomic architecture of SPAST predisposes to diverse CNV alleles with distinct transcriptional--and possibly phenotypic--consequences. Moreover, we provide further mechanistic insights into Alu-mediated copy-number change that are extendable to other loci.
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Copy Number Variation in Chickens: A Review and Future Prospects. MICROARRAYS 2014; 3:24-38. [PMID: 27605028 PMCID: PMC5003453 DOI: 10.3390/microarrays3010024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 01/22/2014] [Accepted: 01/23/2014] [Indexed: 12/19/2022]
Abstract
DNA sequence variations include nucleotide substitution, deletion, insertion, translocation and inversion. Deletion or insertion of a large DNA segment in the genome, referred to as copy number variation (CNV), has caught the attention of many researchers recently. It is believed that CNVs contribute significantly to genome variability, and thus contribute to phenotypic variability. In chickens, genome-wide surveys with array comparative genome hybridization (aCGH), SNP chip detection or whole genome sequencing have revealed a large number of CNVs. A large portion of chicken CNVs involves protein coding or regulatory sequences. A few CNVs have been demonstrated to be the determinant factors for single gene traits, such as late-feathering, pea-comb and dermal hyperpigmentation. The phenotypic effects of the majority of chicken CNVs are to be delineated.
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Cook GW, Konkel MK, Walker JA, Bourgeois MG, Fullerton ML, Fussell JT, Herbold HD, Batzer MA. A comparison of 100 human genes using an alu element-based instability model. PLoS One 2013; 8:e65188. [PMID: 23755193 PMCID: PMC3670932 DOI: 10.1371/journal.pone.0065188] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 04/23/2013] [Indexed: 02/07/2023] Open
Abstract
The human retrotransposon with the highest copy number is the Alu element. The human genome contains over one million Alu elements that collectively account for over ten percent of our DNA. Full-length Alu elements are randomly distributed throughout the genome in both forward and reverse orientations. However, full-length widely spaced Alu pairs having two Alus in the same (direct) orientation are statistically more prevalent than Alu pairs having two Alus in the opposite (inverted) orientation. The cause of this phenomenon is unknown. It has been hypothesized that this imbalance is the consequence of anomalous inverted Alu pair interactions. One proposed mechanism suggests that inverted Alu pairs can ectopically interact, exposing both ends of each Alu element making up the pair to a potential double-strand break, or "hit". This hypothesized "two-hit" (two double-strand breaks) potential per Alu element was used to develop a model for comparing the relative instabilities of human genes. The model incorporates both 1) the two-hit double-strand break potential of Alu elements and 2) the probability of exon-damaging deletions extending from these double-strand breaks. This model was used to compare the relative instabilities of 50 deletion-prone cancer genes and 50 randomly selected genes from the human genome. The output of the Alu element-based genomic instability model developed here is shown to coincide with the observed instability of deletion-prone cancer genes. The 50 cancer genes are collectively estimated to be 58% more unstable than the randomly chosen genes using this model. Seven of the deletion-prone cancer genes, ATM, BRCA1, FANCA, FANCD2, MSH2, NCOR1 and PBRM1, were among the most unstable 10% of the 100 genes analyzed. This algorithm may lay the foundation for comparing genetic risks posed by structural variations that are unique to specific individuals, families and people groups.
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Affiliation(s)
- George W. Cook
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Miriam K. Konkel
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Jerilyn A. Walker
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Matthew G. Bourgeois
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Mitchell L. Fullerton
- Department of Bioengineering, Clemson University, Clemson, South Carolina, United States of America
| | - John T. Fussell
- Electrochemical Materials, Louisiana Business and Technology Center, Baton Rouge, Louisiana, United States of America
| | - Heath D. Herbold
- Albemarle Corporation, Pasadena, Texas, United States of America
| | - Mark A. Batzer
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
- * E-mail:
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Abstract
PURPOSE OF REVIEW Chromosome 22, the first human chromosome to be completely sequenced, is prone to genomic alterations. Copy-number variants (CNVs) are common because of an enrichment of low-copy repeat sequences that precipitate a high frequency of nonallelic homologous misalignments and unequal recombination during meiosis. Among these is one of the most common multiple anomaly syndromes in humans and the most common microdeletion syndrome, velocardiofacial syndrome (VCFS), also known as 22q11.2 deletion syndrome and DiGeorge syndrome. This review will focus on the recent literature dealing with both the molecular and clinical aspects of chromosome 22 genomic variations. Although the literature covering this area is expansive, the majority is descriptive or analytical of the problems presented by these genomic disorders, and there is little evidence of translational research including treatment outcomes. RECENT FINDINGS With the increased use of microarray analysis in both research and clinical practice, variations in CNVs are becoming elucidated. Genomic analysis continues to characterize genes and gene effect. Research on the COMT gene continues to yield interesting findings, including a possible sex-mediated effect because of its regulatory role with estrogen. There is a small amount of treatment outcome data relevant to neuropsychiatric disorders in VCFS, but based on small samples and short-term follow-up. SUMMARY Although hundreds of studies in the past year have focused on genomic disorders of chromosome 22, little progress has been made in the implementation of translational research, even for more common disorders including VCFS.
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Jelassi A, Slimani A, Rabès JP, Jguirim I, Abifadel M, Boileau C, Najah M, M'rabet S, Mzid J, Slimane MN, Varret M. Genomic characterization of two deletions in the LDLR gene in Tunisian patients with familial hypercholesterolemia. Clin Chim Acta 2012; 414:146-51. [DOI: 10.1016/j.cca.2012.08.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 07/31/2012] [Accepted: 08/04/2012] [Indexed: 12/20/2022]
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Mehlotra RK, Zimmerman PA, Weinberg A, Jurevic RJ. Variation in human β-defensin genes: new insights from a multi-population study. Int J Immunogenet 2012. [PMID: 23194186 DOI: 10.1111/iji.12021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Human β-defensin 2 (hBD-2) and hBD-3, encoded by DEFB4 and DEFB103A, respectively, have shown anti-HIV activity, and both genes exhibit copy number variation (CNV). Although the role of hBD-1, encoded by DEFB1, in HIV-1 infection is less clear, single nucleotide polymorphisms (SNPs) in DEFB1 may influence viral loads and disease progression. We examined the distribution of DEFB1 SNPs and DEFB4/103A CNV, and the relationship between DEFB1 SNPs and DEFB4/103A CNV using samples from two HIV/AIDS cohorts from the United States (n = 150) and five diverse populations from the Coriell Cell Repositories (n = 46). We determined the frequencies of 10 SNPs in DEFB1 using a post-PCR, oligonucleotide ligation detection reaction-fluorescent microsphere assay, and CNV in DEFB4/103A by real-time quantitative PCR. There were noticeable differences in the frequencies of DEFB1 SNP alleles and haplotypes among various racial/ethnic groups. The DEFB4/103A copy numbers varied from 2 to 8 (median, 4), and there was a significant difference between the copy numbers of self-identified whites and blacks in the US cohorts (Mann-Whitney U-test P = 0.04). A significant difference was observed in the distribution of DEFB4/103A CNV among DEFB1 -52G/A and -390T/A genotypes (Kruskal-Wallis P = 0.017 and 0.026, respectively), while not in the distribution of DEFB4/103A CNV among -52G/A_-44C/G_-20G/A diplotypes. These observations provide additional insights for further investigating the complex interplay between β-defensin genetic polymorphisms and susceptibility to, or the progression or severity of, HIV infection/disease.
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Affiliation(s)
- R K Mehlotra
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, OH, USA
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Szafranski P, Dharmadhikari AV, Brosens E, Gurha P, Kolodziejska KE, Zhishuo O, Dittwald P, Majewski T, Mohan KN, Chen B, Person RE, Tibboel D, de Klein A, Pinner J, Chopra M, Malcolm G, Peters G, Arbuckle S, Guiang SF, Hustead VA, Jessurun J, Hirsch R, Witte DP, Maystadt I, Sebire N, Fisher R, Langston C, Sen P, Stankiewicz P. Small noncoding differentially methylated copy-number variants, including lncRNA genes, cause a lethal lung developmental disorder. Genome Res 2012; 23:23-33. [PMID: 23034409 PMCID: PMC3530681 DOI: 10.1101/gr.141887.112] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
An unanticipated and tremendous amount of the noncoding sequence of the human genome is transcribed. Long noncoding RNAs (lncRNAs) constitute a significant fraction of non-protein-coding transcripts; however, their functions remain enigmatic. We demonstrate that deletions of a small noncoding differentially methylated region at 16q24.1, including lncRNA genes, cause a lethal lung developmental disorder, alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV), with parent-of-origin effects. We identify overlapping deletions 250 kb upstream of FOXF1 in nine patients with ACD/MPV that arose de novo specifically on the maternally inherited chromosome and delete lung-specific lncRNA genes. These deletions define a distant cis-regulatory region that harbors, besides lncRNA genes, also a differentially methylated CpG island, binds GLI2 depending on the methylation status of this CpG island, and physically interacts with and up-regulates the FOXF1 promoter. We suggest that lung-transcribed 16q24.1 lncRNAs may contribute to long-range regulation of FOXF1 by GLI2 and other transcription factors. Perturbation of lncRNA-mediated chromatin interactions may, in general, be responsible for position effect phenomena and potentially cause many disorders of human development.
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Affiliation(s)
- Przemyslaw Szafranski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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Simmons AD, Carvalho CMB, Lupski JR. What have studies of genomic disorders taught us about our genome? Methods Mol Biol 2012; 838:1-27. [PMID: 22228005 DOI: 10.1007/978-1-61779-507-7_1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The elucidation of genomic disorders began with molecular technologies that enabled detection of genomic changes which were (a) smaller than those resolved by traditional cytogenetics (less than 5 Mb) and (b) larger than what could be determined by conventional gel electrophoresis. Methods such as pulsed field gel electrophoresis (PFGE) and fluorescent in situ hybridization (FISH) could resolve such changes but were limited to locus-specific studies. The study of genomic disorders has rapidly advanced with the development of array-based techniques. These enabled examination of the entire human genome at a higher level of resolution, thus allowing elucidation of the basis of many new disorders, mechanisms that result in genomic changes that can result in copy number variation (CNV), and most importantly, a deeper understanding of the characteristics, features, and plasticity of our genome. In this chapter, we focus on the structural and architectural features of the genome, which can potentially result in genomic instability, delineate how mechanisms, such as NAHR, NHEJ, and FoSTeS/MMBIR lead to disease-causing rearrangements, and briefly describe the relationship between the leading methods presently used in studying genomic disorders. We end with a discussion on our new understanding about our genome including: the contribution of new mutation CNV to disease, the abundance of mosaicism, the extent of subtelomeric rearrangements, the frequency of de novo rearrangements associated with sporadic birth defects, the occurrence of balanced and unbalanced translocations, the increasing discovery of insertional translocations, the exploration of complex rearrangements and exonic CNVs. In the postgenomic era, our understanding of the genome has advanced very rapidly as the level of technical resolution has become higher. This leads to a greater understanding of the effects of rearrangements present both in healthy subjects and individuals with clinically relevant phenotypes.
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Yu S, Graf W, Ramalingam A, Brawner S, Joyce J, Fiedler S, Zhou XG, Liu HY. Identification of Copy Number Variants on Human Chromosome 22 in Patients with a Variety of Clinical Findings. Cytogenet Genome Res 2011; 134:260-8. [DOI: 10.1159/000330123] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2011] [Indexed: 12/26/2022] Open
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Lawson ARJ, Hindley GFL, Forshew T, Tatevossian RG, Jamie GA, Kelly GP, Neale GA, Ma J, Jones TA, Ellison DW, Sheer D. RAF gene fusion breakpoints in pediatric brain tumors are characterized by significant enrichment of sequence microhomology. Genome Res 2011; 21:505-14. [PMID: 21393386 DOI: 10.1101/gr.115782.110] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Gene fusions involving members of the RAF family of protein kinases have recently been identified as characteristic aberrations of low-grade astrocytomas, the most common tumors of the central nervous system in children. While it has been shown that these fusions cause constitutive activation of the ERK/MAPK pathway, very little is known about their formation. Here, we present a detailed analysis of RAF gene fusion breakpoints from a well-characterized cohort of 43 low-grade astrocytomas. Our findings show that the rearrangements that generate these RAF gene fusions may be simple or complex and that both inserted nucleotides and microhomology are common at the DNA breakpoints. Furthermore, we identify novel enrichment of microhomologous sequences in the regions immediately flanking the breakpoints. We thus provide evidence that the tandem duplications responsible for these fusions are generated by microhomology-mediated break-induced replication (MMBIR). Although MMBIR has previously been implicated in the pathogenesis of other diseases and the evolution of eukaryotic genomes, we demonstrate here that the proposed details of MMBIR are consistent with a recurrent rearrangement in cancer. Our analysis of repetitive elements, Z-DNA and sequence motifs in the fusion partners identified significant enrichment of the human minisatellite conserved sequence/χ-like element at one side of the breakpoint. Therefore, in addition to furthering our understanding of low-grade astrocytomas, this study provides insights into the molecular mechanistic details of MMBIR and the sequence of events that occur in the formation of genomic rearrangements.
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Affiliation(s)
- Andrew R J Lawson
- Queen Mary University of London, Centre for Neuroscience and Trauma, Blizard Institute of Cell and Molecular Science, Barts and the London School of Medicine and Dentistry, London, United Kingdom
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Cheung AYL, Horvath LM, Grafodatskaya D, Pasceri P, Weksberg R, Hotta A, Carrel L, Ellis J. Isolation of MECP2-null Rett Syndrome patient hiPS cells and isogenic controls through X-chromosome inactivation. Hum Mol Genet 2011; 20:2103-15. [PMID: 21372149 PMCID: PMC3090191 DOI: 10.1093/hmg/ddr093] [Citation(s) in RCA: 205] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Rett syndrome (RTT) is a neurodevelopmental autism spectrum disorder that affects girls due primarily to mutations in the gene encoding methyl-CpG binding protein 2 (MECP2). The majority of RTT patients carry missense and nonsense mutations leading to a hypomorphic MECP2, while null mutations leading to the complete absence of a functional protein are rare. MECP2 is an X-linked gene subject to random X-chromosome inactivation resulting in mosaic expression of mutant MECP2. The lack of human brain tissue motivates the need for alternative human cellular models to study RTT. Here we report the characterization of a MECP2 mutation in a classic female RTT patient involving rearrangements that remove exons 3 and 4 creating a functionally null mutation. To generate human neuron models of RTT, we isolated human induced pluripotent stem (hiPS) cells from RTT patient fibroblasts. RTT-hiPS cells retained the MECP2 mutation, are pluripotent and fully reprogrammed, and retained an inactive X-chromosome in a nonrandom pattern. Taking advantage of the latter characteristic, we obtained a pair of isogenic wild-type and mutant MECP2 expressing RTT-hiPS cell lines that retained this MECP2 expression pattern upon differentiation into neurons. Phenotypic analysis of mutant RTT-hiPS cell-derived neurons demonstrated a reduction in soma size compared with the isogenic control RTT-hiPS cell-derived neurons from the same RTT patient. Analysis of isogenic control and mutant hiPS cell-derived neurons represents a promising source for understanding the pathogenesis of RTT and the role of MECP2 in human neurons.
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Affiliation(s)
- Aaron Y L Cheung
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
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Abstract
Quantitative behavioral genetic studies have made it clear that communication disorders such as reading disability, language impairment, and autism spectrum disorders follow some basic principles: (1) complex disorders have complex causes, in which each clinical disorder is influenced by a number of separate genes; and (2) at least some behaviorally related disorders are influenced by the same genes. Recent advances in molecular and statistical methods have confirmed these principles and are now leading to an understanding of the genes that may be involved in these disorders and how their disruption may affect the development of the brain. The prospect is that the genes involved in these disorders will define a network of interacting neurologic functions and that perturbations of different elements of this network will produce susceptibilities for different disorders. Such knowledge would clarify the underlying deficits in these disorders and could lead to revised diagnostic conceptions. However, these goals are still in the future. Identifying the individual genes in such a network is painstaking, and there have been seemingly contradictory studies along the way. Improvements in study design and additional functional analysis of genes are gradually clarifying many of these issues. When combined with careful phenotypic studies, molecular genetic studies have the potential to refine the clinical definitions of communication disorders and influence their remediation.
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Whibley AC, Plagnol V, Tarpey PS, Abidi F, Fullston T, Choma MK, Boucher CA, Shepherd L, Willatt L, Parkin G, Smith R, Futreal PA, Shaw M, Boyle J, Licata A, Skinner C, Stevenson RE, Turner G, Field M, Hackett A, Schwartz CE, Gecz J, Stratton MR, Raymond FL. Fine-scale survey of X chromosome copy number variants and indels underlying intellectual disability. Am J Hum Genet 2010; 87:173-88. [PMID: 20655035 DOI: 10.1016/j.ajhg.2010.06.017] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 06/14/2010] [Accepted: 06/21/2010] [Indexed: 11/16/2022] Open
Abstract
Copy number variants and indels in 251 families with evidence of X-linked intellectual disability (XLID) were investigated by array comparative genomic hybridization on a high-density oligonucleotide X chromosome array platform. We identified pathogenic copy number variants in 10% of families, with mutations ranging from 2 kb to 11 Mb in size. The challenge of assessing causality was facilitated by prior knowledge of XLID-associated genes and the ability to test for cosegregation of variants with disease through extended pedigrees. Fine-scale analysis of rare variants in XLID families leads us to propose four additional genes, PTCHD1, WDR13, FAAH2, and GSPT2, as candidates for XLID causation and the identification of further deletions and duplications affecting X chromosome genes but without apparent disease consequences. Breakpoints of pathogenic variants were characterized to provide insight into the underlying mutational mechanisms and indicated a predominance of mitotic rather than meiotic events. By effectively bridging the gap between karyotype-level investigations and X chromosome exon resequencing, this study informs discussion of alternative mutational mechanisms, such as noncoding variants and non-X-linked disease, which might explain the shortfall of mutation yield in the well-characterized International Genetics of Learning Disability (IGOLD) cohort, where currently disease remains unexplained in two-thirds of families.
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Affiliation(s)
- Annabel C Whibley
- Department of Medical Genetics, Cambridge Institute for Medical Research, Cambridge CB2 0XY, UK
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Goldmann R, Tichý L, Freiberger T, Zapletalová P, Letocha O, Soska V, Fajkus J, Fajkusová L. Genomic characterization of large rearrangements of the LDLR gene in Czech patients with familial hypercholesterolemia. BMC MEDICAL GENETICS 2010; 11:115. [PMID: 20663204 PMCID: PMC2923121 DOI: 10.1186/1471-2350-11-115] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Accepted: 07/27/2010] [Indexed: 02/02/2023]
Abstract
Background Mutations in the LDLR gene are the most frequent cause of Familial hypercholesterolemia, an autosomal dominant disease characterised by elevated concentrations of LDL in blood plasma. In many populations, large genomic rearrangements account for approximately 10% of mutations in the LDLR gene. Methods DNA diagnostics of large genomic rearrangements was based on Multiple Ligation dependent Probe Amplification (MLPA). Subsequent analyses of deletion and duplication breakpoints were performed using long-range PCR, PCR, and DNA sequencing. Results In set of 1441 unrelated FH patients, large genomic rearrangements were found in 37 probands. Eight different types of rearrangements were detected, from them 6 types were novel, not described so far. In all rearrangements, we characterized their exact extent and breakpoint sequences. Conclusions Sequence analysis of deletion and duplication breakpoints indicates that intrachromatid non-allelic homologous recombination (NAHR) between Alu elements is involved in 6 events, while a non-homologous end joining (NHEJ) is implicated in 2 rearrangements. Our study thus describes for the first time NHEJ as a mechanism involved in genomic rearrangements in the LDLR gene.
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Affiliation(s)
- Radan Goldmann
- University Hospital Brno, Centre of Molecular Biology and Gene Therapy, Cernopolní 9, CZ-62500 Brno, Czech Republic
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Ostrovnaya I, Nanjangud G, Olshen AB. A classification model for distinguishing copy number variants from cancer-related alterations. BMC Bioinformatics 2010; 11:297. [PMID: 20525196 PMCID: PMC2897829 DOI: 10.1186/1471-2105-11-297] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 06/02/2010] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Both somatic copy number alterations (CNAs) and germline copy number variants (CNVs) that are prevalent in healthy individuals can appear as recurrent changes in comparative genomic hybridization (CGH) analyses of tumors. In order to identify important cancer genes CNAs and CNVs must be distinguished. Although the Database of Genomic Variants (DGV) contains a list of all known CNVs, there is no standard methodology to use the database effectively. RESULTS We develop a prediction model that distinguishes CNVs from CNAs based on the information contained in the DGV and several other variables, including segment's length, height, closeness to a telomere or centromere and occurrence in other patients. The models are fitted on data from glioblastoma and their corresponding normal samples that were collected as part of The Cancer Genome Atlas project and hybridized to Agilent 244 K arrays. CONCLUSIONS Using the DGV alone CNVs in the test set can be correctly identified with about 85% accuracy if the outliers are removed before segmentation and with 72% accuracy if the outliers are included, and additional variables improve the prediction by about 2-3% and 12%, respectively. Final models applied to data from ovarian tumors have about 90% accuracy with all the variables and 86% accuracy with the DGV alone.
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Affiliation(s)
- Irina Ostrovnaya
- Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
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Coin LJM, Asher JE, Walters RG, El-Sayed Moustafa JS, de Smith AJ, Sladek R, Balding DJ, Froguel P, Blakemore AIF. cnvHap: an integrative population and haplotype–based multiplatform model of SNPs and CNVs. Nat Methods 2010; 7:541-6. [DOI: 10.1038/nmeth.1466] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 05/05/2010] [Indexed: 11/09/2022]
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Genomic profile of copy number variants on the short arm of human chromosome 8. Eur J Hum Genet 2010; 18:1114-20. [PMID: 20461109 DOI: 10.1038/ejhg.2010.66] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
We evaluated 966 consecutive pediatric patients with various developmental disorders by high-resolution microarray-based comparative genomic hybridization and found 10 individuals with pathogenic copy number variants (CNVs) on the short arm of chromosome 8 (8p), representing approximately 1% of the patients analyzed. Two patients with 8p terminal deletion associated with interstitial inverted duplication (inv dup del(8p)) had different mechanisms leading to the formation of a dicentric intermediate during meiosis. Three probands carried an identical ∼5.0 Mb interstitial duplication of chromosome 8p23.1. Four possible hotspots within 8p were observed at nucleotide coordinates of ∼10.45, 24.32-24.82, 32.19-32.77, and 38.94-39.72 Mb involving the formation of recurrent genomic rearrangements. Other CNVs with deletion- or duplication-specific start or stop coordinates on the 8p provide useful information for exploring the basic mechanisms of complex structural rearrangements in the human genome.
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Su SY, Asher JE, Jarvelin MR, Froguel P, Blakemore AIF, Balding DJ, Coin LJM. Inferring combined CNV/SNP haplotypes from genotype data. ACTA ACUST UNITED AC 2010; 26:1437-45. [PMID: 20406911 DOI: 10.1093/bioinformatics/btq157] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
MOTIVATION Copy number variations (CNVs) are increasingly recognized as an substantial source of individual genetic variation, and hence there is a growing interest in investigating the evolutionary history of CNVs as well as their impact on complex disease susceptibility. CNV/SNP haplotypes are critical for this research, but although many methods have been proposed for inferring integer copy number, few have been designed for inferring CNV haplotypic phase and none of these are applicable at genome-wide scale. Here, we present a method for inferring missing CNV genotypes, predicting CNV allelic configuration and for inferring CNV haplotypic phase from SNP/CNV genotype data. Our method, implemented in the software polyHap v2.0, is based on a hidden Markov model, which models the joint haplotype structure between CNVs and SNPs. Thus, haplotypic phase of CNVs and SNPs are inferred simultaneously. A sampling algorithm is employed to obtain a measure of confidence/credibility of each estimate. RESULTS We generated diploid phase-known CNV-SNP genotype datasets by pairing male X chromosome CNV-SNP haplotypes. We show that polyHap provides accurate estimates of missing CNV genotypes, allelic configuration and CNV haplotypic phase on these datasets. We applied our method to a non-simulated dataset-a region on Chromosome 2 encompassing a short deletion. The results confirm that polyHap's accuracy extends to real-life datasets. AVAILABILITY Our method is implemented in version 2.0 of the polyHap software package and can be downloaded from http://www.imperial.ac.uk/medicine/people/l.coin.
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Affiliation(s)
- Shu-Yi Su
- Department of Epidemiology and Biostatistics, School of Public Health, Imperial College, London W2 1PG, UK
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Cheeseman IH, Gomez-Escobar N, Carret CK, Ivens A, Stewart LB, Tetteh KKA, Conway DJ. Gene copy number variation throughout the Plasmodium falciparum genome. BMC Genomics 2009; 10:353. [PMID: 19653891 PMCID: PMC2732925 DOI: 10.1186/1471-2164-10-353] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Accepted: 08/04/2009] [Indexed: 11/17/2022] Open
Abstract
Background Gene copy number variation (CNV) is responsible for several important phenotypes of the malaria parasite Plasmodium falciparum, including drug resistance, loss of infected erythrocyte cytoadherence and alteration of receptor usage for erythrocyte invasion. Despite the known effects of CNV, little is known about its extent throughout the genome. Results We performed a whole-genome survey of CNV genes in P. falciparum using comparative genome hybridisation of a diverse set of 16 laboratory culture-adapted isolates to a custom designed high density Affymetrix GeneChip array. Overall, 186 genes showed hybridisation signals consistent with deletion or amplification in one or more isolate. There is a strong association of CNV with gene length, genomic location, and low orthology to genes in other Plasmodium species. Sub-telomeric regions of all chromosomes are strongly associated with CNV genes independent from members of previously described multigene families. However, ~40% of CNV genes were located in more central regions of the chromosomes. Among the previously undescribed CNV genes, several that are of potential phenotypic relevance are identified. Conclusion CNV represents a major form of genetic variation within the P. falciparum genome; the distribution of gene features indicates the involvement of highly non-random mutational and selective processes. Additional studies should be directed at examining CNV in natural parasite populations to extend conclusions to clinical settings.
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Affiliation(s)
- Ian H Cheeseman
- Department of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
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Alaerts M, Del-Favero J. Searching genetic risk factors for schizophrenia and bipolar disorder: learn from the past and back to the future. Hum Mutat 2009; 30:1139-52. [DOI: 10.1002/humu.21042] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Hastings PJ, Lupski JR, Rosenberg SM, Ira G. Mechanisms of change in gene copy number. Nat Rev Genet 2009. [PMID: 19597530 DOI: 10.1038/nrg2593.mechanisms] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Deletions and duplications of chromosomal segments (copy number variants, CNVs) are a major source of variation between individual humans and are an underlying factor in human evolution and in many diseases, including mental illness, developmental disorders and cancer. CNVs form at a faster rate than other types of mutation, and seem to do so by similar mechanisms in bacteria, yeast and humans. Here we review current models of the mechanisms that cause copy number variation. Non-homologous end-joining mechanisms are well known, but recent models focus on perturbation of DNA replication and replication of non-contiguous DNA segments. For example, cellular stress might induce repair of broken replication forks to switch from high-fidelity homologous recombination to non-homologous repair, thus promoting copy number change.
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Affiliation(s)
- P J Hastings
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.
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Hastings PJ, Lupski JR, Rosenberg SM, Ira G. Mechanisms of change in gene copy number. Nat Rev Genet 2009; 10:551-64. [PMID: 19597530 DOI: 10.1038/nrg2593] [Citation(s) in RCA: 857] [Impact Index Per Article: 57.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Deletions and duplications of chromosomal segments (copy number variants, CNVs) are a major source of variation between individual humans and are an underlying factor in human evolution and in many diseases, including mental illness, developmental disorders and cancer. CNVs form at a faster rate than other types of mutation, and seem to do so by similar mechanisms in bacteria, yeast and humans. Here we review current models of the mechanisms that cause copy number variation. Non-homologous end-joining mechanisms are well known, but recent models focus on perturbation of DNA replication and replication of non-contiguous DNA segments. For example, cellular stress might induce repair of broken replication forks to switch from high-fidelity homologous recombination to non-homologous repair, thus promoting copy number change.
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Affiliation(s)
- P J Hastings
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.
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Vissers LE, Bhatt SS, Janssen IM, Xia Z, Lalani SR, Pfundt R, Derwinska K, de Vries BB, Gilissen C, Hoischen A, Nesteruk M, Wisniowiecka-Kowalnik B, Smyk M, Brunner HG, Cheung SW, van Kessel AG, Veltman JA, Stankiewicz P. Rare pathogenic microdeletions and tandem duplications are microhomology-mediated and stimulated by local genomic architecture. Hum Mol Genet 2009; 18:3579-93. [DOI: 10.1093/hmg/ddp306] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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de Smith AJ, Purmann C, Walters RG, Ellis RJ, Holder SE, Van Haelst MM, Brady AF, Fairbrother UL, Dattani M, Keogh JM, Henning E, Yeo GSH, O'Rahilly S, Froguel P, Farooqi IS, Blakemore AIF. A deletion of the HBII-85 class of small nucleolar RNAs (snoRNAs) is associated with hyperphagia, obesity and hypogonadism. Hum Mol Genet 2009; 18:3257-65. [PMID: 19498035 DOI: 10.1093/hmg/ddp263] [Citation(s) in RCA: 229] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Genetic studies in patients with severe early-onset obesity have provided insights into the molecular and physiological pathways that regulate body weight in humans. We report a 19-year-old male with hyperphagia and severe obesity, mild learning difficulties and hypogonadism, in whom diagnostic tests for Prader-Willi syndrome (PWS) had been negative. We carried out detailed clinical and metabolic phenotyping of this patient and investigated the genetic basis of this obesity syndrome using Agilent 185 k array comparative genomic hybridization (aCGH) and Affymetrix 6.0 genotyping arrays. The identified deletion was validated using multiplex ligation-dependent probe amplification and long-range PCR, followed by breakpoint sequencing which enabled precise localization of the deletion. We identified a approximately 187 kb microdeletion at chromosome 15q11-13 that encompasses non-coding small nucleolar RNAs (including HBII-85 snoRNAs) which were not expressed in peripheral lymphocytes from the patient. Characterization of the clinical phenotype revealed increased ad libitum food intake, normal basal metabolic rate when adjusted for fat-free mass, partial hypogonadotropic hypogonadism and growth failure. We have identified a novel deletion on chromosome 15q11-13 in an individual with hyperphagia, obesity, hypogonadism and other features associated with PWS, which is normally caused by deficiency of several paternally expressed imprinted transcripts within chromosome 15q11-13, a region that includes multiple protein-coding genes as well as several non-coding snoRNAs. These findings provide direct evidence for the role of a particular family of non-coding RNAs, the HBII-85 snoRNA cluster, in human energy homeostasis, growth and reproduction.
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Affiliation(s)
- Adam J de Smith
- Section of Genomic Medicine, Imperial College London, Hammersmith Hospital Campus, London, UK
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de Smith AJ, Walters RG, Froguel P, Blakemore AI. Human genes involved in copy number variation: mechanisms of origin, functional effects and implications for disease. Cytogenet Genome Res 2009; 123:17-26. [PMID: 19287135 DOI: 10.1159/000184688] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2008] [Indexed: 11/19/2022] Open
Abstract
Copy number variants (CNVs) overlap over 7000 genes, many of which are pivotal in biological pathways. The implications of this are profound, with consequences for evolutionary studies, population genetics, gene function and human phenotype, including elucidation of genetic susceptibility to major common diseases, the heritability of which has thus far defied full explanation. Even though this research is still in its infancy, CNVs have already been associated with a number of monogenic, syndromic and complex diseases: the development of high throughput and high resolution techniques for CNV screening is likely to bring further new insights into the contribution of copy number variation to common diseases. Amongst genes overlapped by CNVs, significant enrichments for certain gene ontology categories have been identified, including those related to immune responses and interactions with the environment. Genes in both of these categories are thought to be important in evolutionary adaptation and to be particular targets of natural selection. Thus, a full appreciation of copy number variation may be important for our understanding of human evolution.
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Affiliation(s)
- A J de Smith
- Section of Genomic Medicine, Imperial College London, Hammersmith Hospital, London, UK
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Oliveira C, Senz J, Kaurah P, Pinheiro H, Sanges R, Haegert A, Corso G, Schouten J, Fitzgerald R, Vogelsang H, Keller G, Dwerryhouse S, Grimmer D, Chin SF, Yang HK, Jackson CE, Seruca R, Roviello F, Stupka E, Caldas C, Huntsman D. Germline CDH1 deletions in hereditary diffuse gastric cancer families. Hum Mol Genet 2009; 18:1545-55. [PMID: 19168852 PMCID: PMC2667284 DOI: 10.1093/hmg/ddp046] [Citation(s) in RCA: 157] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Germline CDH1 point or small frameshift mutations can be identified in 30-50% of hereditary diffuse gastric cancer (HDGC) families. We hypothesized that CDH1 genomic rearrangements would be found in HDGC and identified 160 families with either two gastric cancers in first-degree relatives and with at least one diffuse gastric cancer (DGC) diagnosed before age 50, or three or more DGC in close relatives diagnosed at any age. Sixty-seven carried germline CDH1 point or small frameshift mutations. We screened germline DNA from the 93 mutation negative probands for large genomic rearrangements by Multiplex Ligation-Dependent Probe Amplification. Potential deletions were validated by RT-PCR and breakpoints cloned using a combination of oligo-CGH-arrays and long-range-PCR. In-silico analysis of the CDH1 locus was used to determine a potential mechanism for these rearrangements. Six of 93 (6.5%) previously described mutation negative HDGC probands, from low GC incidence populations (UK and North America), carried genomic deletions (UK and North America). Two families carried an identical deletion spanning 193 593 bp, encompassing the full CDH3 sequence and CDH1 exons 1 and 2. Other deletions affecting exons 1, 2, 15 and/or 16 were identified. The statistically significant over-representation of Alus around breakpoints indicates it as a likely mechanism for these deletions. When all mutations and deletions are considered, the overall frequency of CDH1 alterations in HDGC is approximately 46% (73/160). CDH1 large deletions occur in 4% of HDGC families by mechanisms involving mainly non-allelic homologous recombination in Alu repeat sequences. As the finding of pathogenic CDH1 mutations is useful for management of HDGC families, screening for deletions should be offered to at-risk families.
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Affiliation(s)
- Carla Oliveira
- Institute of Molecular Pathology and Immunology, University of Porto, Portugal
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