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Liaci C, Camera M, Caslini G, Rando S, Contino S, Romano V, Merlo GR. Neuronal Cytoskeleton in Intellectual Disability: From Systems Biology and Modeling to Therapeutic Opportunities. Int J Mol Sci 2021; 22:ijms22116167. [PMID: 34200511 PMCID: PMC8201358 DOI: 10.3390/ijms22116167] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 05/25/2021] [Accepted: 06/04/2021] [Indexed: 02/06/2023] Open
Abstract
Intellectual disability (ID) is a pathological condition characterized by limited intellectual functioning and adaptive behaviors. It affects 1–3% of the worldwide population, and no pharmacological therapies are currently available. More than 1000 genes have been found mutated in ID patients pointing out that, despite the common phenotype, the genetic bases are highly heterogeneous and apparently unrelated. Bibliomic analysis reveals that ID genes converge onto a few biological modules, including cytoskeleton dynamics, whose regulation depends on Rho GTPases transduction. Genetic variants exert their effects at different levels in a hierarchical arrangement, starting from the molecular level and moving toward higher levels of organization, i.e., cell compartment and functions, circuits, cognition, and behavior. Thus, cytoskeleton alterations that have an impact on cell processes such as neuronal migration, neuritogenesis, and synaptic plasticity rebound on the overall establishment of an effective network and consequently on the cognitive phenotype. Systems biology (SB) approaches are more focused on the overall interconnected network rather than on individual genes, thus encouraging the design of therapies that aim to correct common dysregulated biological processes. This review summarizes current knowledge about cytoskeleton control in neurons and its relevance for the ID pathogenesis, exploiting in silico modeling and translating the implications of those findings into biomedical research.
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Affiliation(s)
- Carla Liaci
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy; (C.L.); (M.C.); (G.C.); (S.R.)
| | - Mattia Camera
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy; (C.L.); (M.C.); (G.C.); (S.R.)
| | - Giovanni Caslini
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy; (C.L.); (M.C.); (G.C.); (S.R.)
| | - Simona Rando
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy; (C.L.); (M.C.); (G.C.); (S.R.)
| | - Salvatore Contino
- Department of Engineering, University of Palermo, Viale delle Scienze Ed. 8, 90128 Palermo, Italy;
| | - Valentino Romano
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze Ed. 16, 90128 Palermo, Italy;
| | - Giorgio R. Merlo
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy; (C.L.); (M.C.); (G.C.); (S.R.)
- Correspondence: ; Tel.: +39-0116706449; Fax: +39-0116706432
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Al-Sarraj Y, Al-Dous E, Taha RZ, Ahram D, Alshaban F, Tolfat M, El-Shanti H, Albagha OM. Family-Based Genome-Wide Association Study of Autism Spectrum Disorder in Middle Eastern Families. Genes (Basel) 2021; 12:761. [PMID: 34069769 PMCID: PMC8157263 DOI: 10.3390/genes12050761] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 05/13/2021] [Accepted: 05/13/2021] [Indexed: 12/20/2022] Open
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disease characterized by abnormalities in language and social communication with substantial clinical heterogeneity. Genetic factors play an important role in ASD with heritability estimated between 70% to 80%. Genome-wide association studies (GWAS) have identified multiple loci associated with ASD. However, most studies were performed on European populations and little is known about the genetic architecture of ASD in Middle Eastern populations. Here, we report the first GWAS of ASD in the Middle eastern population of Qatar. We analyzed 171 families with ASD, using linear mixed models adjusting for relatedness and other confounders. Results showed that common single nucleotide polymorphisms (SNP) in seven loci are associated with ASD (p < 1 × 10-5). Although the identified loci did not reach genome-wide significance, many of the top associated SNPs are located within or near genes that have been implicated in ASD or related neurodevelopmental disorders. These include GORASP2, GABBR2, ANKS6, THSD4, ERCC6L, ARHGEF6, and HDAC8. Additionally, three of the top associated SNPs were significantly associated with gene expression. We also found evidence of association signals in two previously reported ASD-susceptibility loci (rs10099100 and rs4299400). Our results warrant further functional studies and replication to provide further insights into the genetic architecture of ASD.
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Affiliation(s)
- Yasser Al-Sarraj
- College of Health and Life Sciences, Hamad Bin Khalifa University, Doha 34110, Qatar; (Y.A.-S.); (E.A.-D.)
- Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University, Doha 34110, Qatar; (R.Z.T.); (D.A.); (F.A.); (H.E.-S.)
| | - Eman Al-Dous
- College of Health and Life Sciences, Hamad Bin Khalifa University, Doha 34110, Qatar; (Y.A.-S.); (E.A.-D.)
- Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University, Doha 34110, Qatar; (R.Z.T.); (D.A.); (F.A.); (H.E.-S.)
| | - Rowaida Z. Taha
- Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University, Doha 34110, Qatar; (R.Z.T.); (D.A.); (F.A.); (H.E.-S.)
| | - Dina Ahram
- Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University, Doha 34110, Qatar; (R.Z.T.); (D.A.); (F.A.); (H.E.-S.)
- Division of Nephrology, Columbia University Medical Center, New York, NY 10032, USA
| | - Fouad Alshaban
- Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University, Doha 34110, Qatar; (R.Z.T.); (D.A.); (F.A.); (H.E.-S.)
| | - Mohammed Tolfat
- The Shafallah Center for Children with Special Needs, Doha 33123, Qatar;
| | - Hatem El-Shanti
- Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University, Doha 34110, Qatar; (R.Z.T.); (D.A.); (F.A.); (H.E.-S.)
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Omar M.E. Albagha
- College of Health and Life Sciences, Hamad Bin Khalifa University, Doha 34110, Qatar; (Y.A.-S.); (E.A.-D.)
- Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University, Doha 34110, Qatar; (R.Z.T.); (D.A.); (F.A.); (H.E.-S.)
- Centre for Genomic and Experimental Medicine, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
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3
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Zhu C, Cheng C, Wang Y, Muhammad W, Liu S, Zhu W, Shao B, Zhang Z, Yan X, He Q, Xu Z, Yu C, Qian X, Lu L, Zhang S, Zhang Y, Xiong W, Gao X, Xu Z, Chai R. Loss of ARHGEF6 Causes Hair Cell Stereocilia Deficits and Hearing Loss in Mice. Front Mol Neurosci 2018; 11:362. [PMID: 30333726 PMCID: PMC6176010 DOI: 10.3389/fnmol.2018.00362] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 09/13/2018] [Indexed: 11/13/2022] Open
Abstract
ARHGEF6 belongs to the family of guanine nucleotide exchange factors (GEFs) for Rho GTPases, and it specifically activates Rho GTPases CDC42 and RAC1. Arhgef6 is the X-linked intellectual disability gene also known as XLID46, and clinical features of patients carrying Arhgef6 mutations include intellectual disability and, in some cases, sensorineural hearing loss. Rho GTPases act as molecular switches in many cellular processes. Their activities are regulated by binding or hydrolysis of GTP, which is facilitated by GEFs and GTPase-activating proteins, respectively. RAC1 and CDC42 have been shown to play important roles in hair cell (HC) stereocilia development. However, the role of ARHGEF6 in inner ear development and hearing function has not yet been investigated. Here, we found that ARHGEF6 is expressed in mouse cochlear HCs, including the HC stereocilia. We established Arhgef6 knockdown mice using the clustered regularly interspaced short palindromic repeat-associated Cas9 nuclease (CRISPR-Cas9) genome editing technique. We showed that ARHGEF6 was indispensable for the maintenance of outer hair cell (OHC) stereocilia, and loss of ARHGEF6 in mice caused HC stereocilia deficits that eventually led to progressive HC loss and hearing loss. However, the loss of ARHGEF6 did not affect the synapse density and did not affect the mechanoelectrical transduction currents in OHCs at postnatal day 3. At the molecular level, the levels of active CDC42 and RAC1 were dramatically decreased in the Arhgef6 knockdown mice, suggesting that ARHGEF6 regulates stereocilia maintenance through RAC1/CDC42.
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Affiliation(s)
- Chengwen Zhu
- Department of Otolaryngology Head and Neck Surgery, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China.,Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, China.,Research Institute of Otolaryngology, Nanjing, China
| | - Cheng Cheng
- Department of Otolaryngology Head and Neck Surgery, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China.,Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, China.,Research Institute of Otolaryngology, Nanjing, China.,Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Yanfei Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan, China.,Shandong Provincial Collaborative Innovation Center of Cell Biology, Shandong Normal University, Jinan, China
| | - Waqas Muhammad
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, China.,Department of Biotechnology, Federal Urdu University of Arts, Science and Technology, Karachi, Pakistan
| | - Shuang Liu
- School of Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
| | - Weijie Zhu
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Buwei Shao
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Zhong Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Xiaoqian Yan
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Qingqing He
- Department of Otolaryngology Head and Neck Surgery, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China
| | - Zhengrong Xu
- Department of Otolaryngology Head and Neck Surgery, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China
| | - Chenjie Yu
- Department of Otolaryngology Head and Neck Surgery, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China
| | - Xiaoyun Qian
- Department of Otolaryngology Head and Neck Surgery, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China
| | - Ling Lu
- Department of Otolaryngology Head and Neck Surgery, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China
| | - Shasha Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, China.,Research Institute of Otolaryngology, Nanjing, China.,Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China.,Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, China
| | - Yuan Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Wei Xiong
- School of Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
| | - Xia Gao
- Department of Otolaryngology Head and Neck Surgery, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China.,Research Institute of Otolaryngology, Nanjing, China
| | - Zhigang Xu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan, China.,Shandong Provincial Collaborative Innovation Center of Cell Biology, Shandong Normal University, Jinan, China
| | - Renjie Chai
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, China.,Research Institute of Otolaryngology, Nanjing, China.,Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China.,Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, China.,Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China
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4
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Betancur C. Etiological heterogeneity in autism spectrum disorders: more than 100 genetic and genomic disorders and still counting. Brain Res 2010; 1380:42-77. [PMID: 21129364 DOI: 10.1016/j.brainres.2010.11.078] [Citation(s) in RCA: 578] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 11/22/2010] [Accepted: 11/23/2010] [Indexed: 12/31/2022]
Abstract
There is increasing evidence that autism spectrum disorders (ASDs) can arise from rare highly penetrant mutations and genomic imbalances. The rare nature of these variants, and the often differing orbits of clinical and research geneticists, can make it difficult to fully appreciate the extent to which we have made progress in understanding the genetic etiology of autism. In fact, there is a persistent view in the autism research community that there are only a modest number of autism loci known. We carried out an exhaustive review of the clinical genetics and research genetics literature in an attempt to collate all genes and recurrent genomic imbalances that have been implicated in the etiology of ASD. We provide data on 103 disease genes and 44 genomic loci reported in subjects with ASD or autistic behavior. These genes and loci have all been causally implicated in intellectual disability, indicating that these two neurodevelopmental disorders share common genetic bases. A genetic overlap between ASD and epilepsy is also apparent in many cases. Taken together, these findings clearly show that autism is not a single clinical entity but a behavioral manifestation of tens or perhaps hundreds of genetic and genomic disorders. Increased recognition of the etiological heterogeneity of ASD will greatly expand the number of target genes for neurobiological investigations and thereby provide additional avenues for the development of pathway-based pharmacotherapy. Finally, the data provide strong support for high-resolution DNA microarrays as well as whole-exome and whole-genome sequencing as critical approaches for identifying the genetic causes of ASDs.
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Martínez F, Martínez-Garay I, Oltra S, Moltó MD, Orellana C, Monfort S, Prieto F, Tejada I. Localization of MRX82: A new nonsyndromic X-linked mental retardation locus to Xq24-q25 in a Basque family. Am J Med Genet A 2004; 131:174-8. [PMID: 15526294 DOI: 10.1002/ajmg.a.30352] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Clinical and molecular studies are reported on a Basque family (MRX82) with nonsyndromic X-linked mental retardation (XLMR) in five affected males. A total of 38 microsatellite markers were typed. The XLMR locus has been linked to DXS8067, DXS1001, DXS425, DXS7877, and DXS1183 with a maximum LOD score of 2.4. The haplotype studies and multipoint linkage analysis suggest a localization of the MRX82 locus to an interval of 7.6 Mb defined by markers DXS6805 and DXS7346, in Xq24 and Xq25, respectively. No gene contained in this interval has been so far associated with nonsyndromic mental retardation, except for GRIA3, disrupted by a balanced translocation in a female patient with bipolar affective disorder and mental retardation. However, the search for mutations of this gene did not showed a pathogenic mutation in the present family. Given that there are other eight MRX families overlapping this interval, none of them with known mutation, we conclude that at least one new gene responsible for nonsyndromic mental retardation is located in this region.
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6
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Vitale E, Specchia C, Devoto M, Angius A, Rong S, Rocchi M, Schwalb M, Demelas L, Paglietti D, Manca S, Mastropaolo C, Serra G. Novel X-linked mental retardation syndrome with short stature maps to Xq24. AMERICAN JOURNAL OF MEDICAL GENETICS 2001; 103:1-8. [PMID: 11562927 DOI: 10.1002/ajmg.1495] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We describe a large family from Sardinia, Italy, in which a novel X- linked mental retardation (XLMR) syndrome segregates. The phenotype observed in the 8 affected males includes severe mental retardation (MR), lack of speech, coarse face, distinctive skeletal features with short stature, brachydactyly of fingers and toes, small downslanting palpebral fissures, large bulbous nose, hypoplastic ear lobe and macrostomia. Carrier females are not mentally retarded, although some of them have mild dysmorphic features such as minor ear lobe abnormalities, as well as language and learning problems. Linkage analysis for X-chromosome markers resulted in a maximum lod score of 3.61 with marker DXS1001 in Xq24. Recombination observed with flanking markers identified a region of 16 cM for further study. None of the other XLMR syndromes known to map in the same region shows the same composite phenotype. This evidence strongly suggests that the genetic disease in this family is unique.
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Affiliation(s)
- E Vitale
- Department of Microbiology and Molecular Genetics, UMDNJ New Jersey Medical School, Newark, New Jersey 07103-2714, USA.
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7
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Lower KM, Gecz J. Characterization of ARHGEF6, a guanine nucleotide exchange factor for Rho GTPases and a candidate gene for X-linked mental retardation: mutation screening in Börjeson-Forssman-Lehmann syndrome and MRX27. AMERICAN JOURNAL OF MEDICAL GENETICS 2001; 100:43-8. [PMID: 11337747 DOI: 10.1002/ajmg.1189] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Börjeson-Forssman-Lehmann syndrome (BFLS) is a syndromic X-linked mental retardation that has been mapped by linkage to Xq26-q27. A nonsyndromic mental retardation family, MRX27, has also been localized to a region of the X chromosome overlapping Xq26-q27. The gene for ARHGEF6 (also known as alphaPIX or Cool-2), a newly identified guanine nucleotide exchange factor, was identified as a potential candidate XLMR gene, due to its location within the BFLS and MRX27 critical regions and its function in the regulation of PAK3 (a known MRX gene). The full coding sequence and genomic structure of the gene for ARHGEF6 was established in silico, based on available genomic, EST, and cDNA sequence information. Mutation analysis in BFLS- and MRX27-affected individuals was carried out. No mutations were found in two BFLS families or MRX27. Although ARHGEF6 is unlikely to be the gene responsible for either BFLS or MRX27, it remains a prime candidate for nonspecific or syndromic mental retardation linked to Xq26.
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Affiliation(s)
- K M Lower
- Centre for Medical Genetics, Department of Cytogenetics and Molecular Genetics, Women's and Children's Hospital, North Adelaide, Australia.
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8
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Kutsche K, Yntema H, Brandt A, Jantke I, Nothwang HG, Orth U, Boavida MG, David D, Chelly J, Fryns JP, Moraine C, Ropers HH, Hamel BC, van Bokhoven H, Gal A. Mutations in ARHGEF6, encoding a guanine nucleotide exchange factor for Rho GTPases, in patients with X-linked mental retardation. Nat Genet 2000; 26:247-50. [PMID: 11017088 DOI: 10.1038/80002] [Citation(s) in RCA: 259] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
X-linked forms of mental retardation (XLMR) include a variety of different disorders and may account for up to 25% of all inherited cases of mental retardation. So far, seven X-chromosomal genes mutated in nonspecific mental retardation (MRX) have been identified: FMR2, GDI1, RPS6KA3, IL1RAPL, TM4SF2, OPHN1 and PAK3 (refs 2-9). The products of the latter two have been implicated in regulation of neural plasticity by controlling the activity of small GTPases of the Rho family. Here we report the identification of a new MRX gene, ARHGEF6 (also known as alphaPIX or Cool-2), encoding a protein with homology to guanine nucleotide exchange factors for Rho GTPases (Rho GEF). Molecular analysis of a reciprocal X/21 translocation in a male with mental retardation showed that this gene in Xq26 was disrupted by the rearrangement. Mutation screening of 119 patients with nonspecific mental retardation revealed a mutation in the first intron of ARHGEF6 (IVS1-11T-->C) in all affected males in a large Dutch family. The mutation resulted in preferential skipping of exon 2, predicting a protein lacking 28 amino acids. ARHGEF6 is the eighth MRX gene identified so far and the third such gene to encode a protein that interacts with Rho GTPases.
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Affiliation(s)
- K Kutsche
- Institut für Humangenetik, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
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9
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Shashi V, Berry MN, Shoaf S, Sciote JJ, Goldstein D, Hart TC. A unique form of mental retardation with a distinctive phenotype maps to Xq26-q27. Am J Hum Genet 2000; 66:469-79. [PMID: 10677307 PMCID: PMC1288100 DOI: 10.1086/302772] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
We report a novel X-linked mental retardation (XLMR) syndrome, with characteristic facial dysmorphic features, segregating in a large North Carolina family. Only males are affected, over four generations. Clinical findings in the seven living affected males include a moderate degree of mental retardation (MR), coarse facies, puffy eyelids, narrow palpebral fissures, prominent supraorbital ridges, a bulbous nose, a prominent lower lip, large ears, obesity, and large testicles. Cephalometric measurements suggest that the affected males have a distinctive craniofacial skeletal structure, when compared with normative measures. Obligate-carrier females are unaffected with MR, but the results of cephalometric skeletal analysis suggest craniofacial dysmorphisms intermediate between affected males and normative control individuals. Unaffected male relatives show no clinical or cephalometric resemblance to affected males. The blood-lymphocyte karyotype and the results of DNA analysis for fragile-X syndrome and of other routine investigations are normal. Linkage analysis for polymorphic DNA markers spanning the X chromosome established linkage to Xq26-q27. Maximum LOD scores were obtained at marker DXS1047 (maximum LOD score = 3.1 at recombination fraction 0). By use of haplotype analysis, we have localized the gene for this condition to an 18-cM genetic interval flanked by ATA59C05 and GATA31E08. On the basis of both the clinical phenotype and the mapping data, we were able to exclude other reported XLMR conditions. Therefore, we believe that a unique recessive XLMR syndrome with a distinctive and recognizable phenotype is represented in this family.
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Affiliation(s)
- V Shashi
- Section on Medical Genetics, Department of Pediatrics, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
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Steingruber HE, Dunham A, Coffey AJ, Clegg SM, Howell GR, Maslen GL, Scott CE, Gwilliam R, Hunt PJ, Sotheran EC, Huckle EJ, Hunt SE, Dhami P, Soderlund C, Leversha MA, Bentley DR, Ross MT. High-resolution landmark framework for the sequence-ready mapping of Xq23-q26.1. Genome Res 1999; 9:751-62. [PMID: 10447510 PMCID: PMC310799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
We have established a landmark framework map over 20-25 Mb of the long arm of the human X chromosome using yeast artificial chromosome (YAC) clones. The map has approximately one landmark per 45 kb of DNA and stretches from DXS7531 in proximal Xq23 to DXS895 in proximal Xq26, connecting to published framework maps on its proximal and distal sides. There are three gaps in the framework map resulting from the failure to obtain clone coverage from the YAC resources available. Estimates of the maximum sizes of these gaps have been obtained. The four YAC contigs have been positioned and oriented using somatic-cell hybrids and fluorescence in situ hybridization, and the largest is estimated to cover approximately 15 Mb of DNA. The framework map is being used to assemble a sequence-ready map in large-insert bacterial clones, as part of an international effort to complete the sequence of the X chromosome. PAC and BAC contigs currently cover 18 Mb of the region, and from these, 12 Mb of finished sequence is available.
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Affiliation(s)
- H E Steingruber
- The Sanger Centre, Wellcome Trust Genome Campus, Hinxton, UK
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11
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Steingruber HE, Dunham A, Coffey AJ, Clegg SM, Howell GR, Maslen GL, Scott CE, Gwilliam R, Hunt PJ, Sotheran EC, Huckle EJ, Hunt SE, Dhami P, Soderlund C, Leversha MA, Bentley DR, Ross MT. High-Resolution Landmark Framework for the Sequence-Ready Mapping of Xq23–q26.1. Genome Res 1999. [DOI: 10.1101/gr.9.8.751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We have established a landmark framework map over 20–25 Mb of the long arm of the human X chromosome using yeast artificial chromosome (YAC) clones. The map has approximately one landmark per 45 kb of DNA and stretches from DXS7531 in proximal Xq23 to DXS895 in proximal Xq26, connecting to published framework maps on its proximal and distal sides. There are three gaps in the framework map resulting from the failure to obtain clone coverage from the YAC resources available. Estimates of the maximum sizes of these gaps have been obtained. The four YAC contigs have been positioned and oriented using somatic-cell hybrids and fluorescence in situ hybridization, and the largest is estimated to cover ∼15 Mb of DNA. The framework map is being used to assemble a sequence-ready map in large-insert bacterial clones, as part of an international effort to complete the sequence of the X chromosome. PAC and BAC contigs currently cover 18 Mb of the region, and from these, 12 Mb of finished sequence is available.
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12
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van Roosmalen T, Smits AP, Thoonen GH, Hamel BC, Assman-Hulmans CF, Gabreels FJ. Psychometric assessment of families with X-linked mental retardation. AMERICAN JOURNAL OF MEDICAL GENETICS 1999; 83:264-7. [PMID: 10208159 DOI: 10.1002/(sici)1096-8628(19990402)83:4<264::aid-ajmg6>3.0.co;2-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
As part of an integrated approach to DNA-linkage analysis in X-linked mental retardation (XLMR), 29 members of five families suspected of having XLMR underwent psychometric assessment. Mental retardation was confirmed in all participants. The range of mental retardation varied from mild to profound within and between families. In addition, these preliminary results indicated family-specific cognitive profiles in MRX45 and MRX46. The fact that two non-overlapping loci were involved provides strong evidence that specific cognitive profiles are linked to specific loci (genes) in mental retardation. We therefore recommend the application of standardised psychometric tests for the assessment of XLMR.
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Affiliation(s)
- T van Roosmalen
- Child Neurology Center, University Hospital Nijmegen, The Netherlands
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