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Duan R, Hijazi H, Gulec EY, Eker HK, Costa SR, Sahin Y, Ocak Z, Isikay S, Ozalp O, Bozdogan S, Aslan H, Elcioglu N, Bertola DR, Gezdirici A, Du H, Fatih JM, Grochowski CM, Akay G, Jhangiani SN, Karaca E, Gu S, Coban-Akdemir Z, Posey JE, Bayram Y, Sutton VR, Carvalho CM, Pehlivan D, Gibbs RA, Lupski JR. Developmental genomics of limb malformations: Allelic series in association with gene dosage effects contribute to the clinical variability. HGG ADVANCES 2022; 3:100132. [PMID: 36035248 PMCID: PMC9403727 DOI: 10.1016/j.xhgg.2022.100132] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 07/19/2022] [Indexed: 11/26/2022] Open
Abstract
Genetic heterogeneity, reduced penetrance, and variable expressivity, the latter including asymmetric body axis plane presentations, have all been described in families with congenital limb malformations (CLMs). Interfamilial and intrafamilial heterogeneity highlight the complexity of the underlying genetic pathogenesis of these developmental anomalies. Family-based genomics by exome sequencing (ES) and rare variant analyses combined with whole-genome array-based comparative genomic hybridization were implemented to investigate 18 families with limb birth defects. Eleven of 18 (61%) families revealed explanatory variants, including 7 single-nucleotide variant alleles and 3 copy number variants (CNVs), at previously reported "disease trait associated loci": BHLHA9, GLI3, HOXD cluster, HOXD13, NPR2, and WNT10B. Breakpoint junction analyses for all three CNV alleles revealed mutational signatures consistent with microhomology-mediated break-induced replication, a mechanism facilitated by Alu/Alu-mediated rearrangement. Homozygous duplication of BHLHA9 was observed in one Turkish kindred and represents a novel contributory genetic mechanism to Gollop-Wolfgang Complex (MIM: 228250), where triplication of the locus has been reported in one family from Japan (i.e., 4n = 2n + 2n versus 4n = 3n + 1n allelic configurations). Genes acting on limb patterning are sensitive to a gene dosage effect and are often associated with an allelic series. We extend an allele-specific gene dosage model to potentially assist, in an adjuvant way, interpretations of interconnections among an allelic series, clinical severity, and reduced penetrance of the BHLHA9-related CLM spectrum.
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Affiliation(s)
- Ruizhi Duan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Hadia Hijazi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Elif Yilmaz Gulec
- Department of Medical Genetics, School of Medicine, Istanbul Medeniyet University, Istanbul, Turkey
| | | | - Silvia R. Costa
- Human Genome and Stem Cell Research Center, Institute of Bioscience, Universidade de São Paulo, São Paulo, Brazil
| | - Yavuz Sahin
- Medical Genetics, Genoks Genetics Center, Ankara, Turkey
| | - Zeynep Ocak
- Department of Medical Genetics, Faculty of Medicine, Istinye University, Istanbul, Turkey
| | - Sedat Isikay
- Department of Pediatric Neurology, Faculty of Medicine, Gaziantep University, Gaziantep, Turkey
| | - Ozge Ozalp
- Department of Medical Genetics, Adana City Training and Research Hospital, Adana, Turkey
| | - Sevcan Bozdogan
- Department of Medical Genetics, Faculty of Medicine, Cukurova University, Adana, Turkey
| | - Huseyin Aslan
- Department of Medical Genetics, Adana City Training and Research Hospital, Adana, Turkey
| | - Nursel Elcioglu
- Department of Pediatric Genetics, School of Medicine, Marmara University, Istanbul, Turkey
- Eastern Mediterranean University Medical School, Magosa, 10 Mersin, Turkey
| | - Débora R. Bertola
- Human Genome and Stem Cell Research Center, Institute of Bioscience, Universidade de São Paulo, São Paulo, Brazil
- Genetics Unit, Instituto da Criança do Hospital das Clínicas da Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Alper Gezdirici
- Department of Medical Genetics, Basaksehir Cam and Sakura City Hospital, Istanbul, Turkey
| | - Haowei Du
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Jawid M. Fatih
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | | | - Gulsen Akay
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Baylor-Hopkins Center for Mendelian Genomics
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Medical Genetics, School of Medicine, Istanbul Medeniyet University, Istanbul, Turkey
- Department of Medical Genetics, Konya City Hospital, Konya, Turkey
- Human Genome and Stem Cell Research Center, Institute of Bioscience, Universidade de São Paulo, São Paulo, Brazil
- Medical Genetics, Genoks Genetics Center, Ankara, Turkey
- Department of Medical Genetics, Faculty of Medicine, Istinye University, Istanbul, Turkey
- Department of Pediatric Neurology, Faculty of Medicine, Gaziantep University, Gaziantep, Turkey
- Department of Medical Genetics, Adana City Training and Research Hospital, Adana, Turkey
- Department of Medical Genetics, Faculty of Medicine, Cukurova University, Adana, Turkey
- Department of Pediatric Genetics, School of Medicine, Marmara University, Istanbul, Turkey
- Eastern Mediterranean University Medical School, Magosa, 10 Mersin, Turkey
- Genetics Unit, Instituto da Criança do Hospital das Clínicas da Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
- Department of Medical Genetics, Basaksehir Cam and Sakura City Hospital, Istanbul, Turkey
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Texas Children’s Hospital, Houston, TX, USA
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | | | - Ender Karaca
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Shen Gu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Zeynep Coban-Akdemir
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Jennifer E. Posey
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Yavuz Bayram
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - V. Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Texas Children’s Hospital, Houston, TX, USA
| | - Claudia M.B. Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Davut Pehlivan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Texas Children’s Hospital, Houston, TX, USA
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
| | - Richard A. Gibbs
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
| | - James R. Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Texas Children’s Hospital, Houston, TX, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
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Bukowska-Olech E, Sowińska-Seidler A, Wierzba J, Jamsheer A. SHFLD3 phenotypes caused by 17p13.3 triplication/ duplication encompassing Fingerin (BHLHA9) invariably. Orphanet J Rare Dis 2022; 17:325. [PMID: 36028842 PMCID: PMC9419377 DOI: 10.1186/s13023-022-02480-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 08/13/2022] [Indexed: 11/21/2022] Open
Abstract
Background Split-hand/ foot malformation with long bone deficiency 3 (SHFLD3) is an extremely rare condition associated with duplications located on 17p13.3, which invariably encompasses the BHLHA9 gene. The disease inherits with variable expressivity and significant incomplete penetrance as high as 50%. Results We have detected 17p13.3 locus one-allele triplication in a male proband from family 1 (F1.1), and duplication in a male proband from family 2 (F2.1) applying array comparative genomic hybridization (array CGH). The rearrangements mapped to the following chromosomal regions–arr[GRCh38] 17p13.3(960254–1291856)×4 in F1.1 and arr[GRCh38] 17p13.3(1227482–1302716)×3 in F2.1. The targeted quantitative PCR revealed that the 17p13.3 locus was also duplicated in the second affected member from family 2 (F2.2; brother of F2.1). In the next step, we performed segregation studies using quantitative PCR and revealed that F1.1 inherited the triplication from his healthy father—F1.2, whereas the locus was unremarkable in the mother of F2.1 & F2.2 and the healthy son of F2.1. However, the duplication was present in a healthy daughter of F2.2, an asymptomatic carrier. The breakpoint analysis allowed to define the exact size and span of the duplicated region in Family 2, i.e., 78,948 bp chr17:1225063–1304010 (HG38). Interestingly, all symptomatic carriers from both families presented with variable SHFLD3 phenotype. The involvement of secondary modifying locus could not be excluded, however, the Sanger sequencing screening of BHLHA9 entire coding sequence was unremarkable for both families. Conclusions We have shed light on the one-allele CNV triplication occurrence that should be considered when a higher probe (over duplication range) signal is noted. Second, all SHFLD3 patients were accurately described regarding infrequent limb phenotypes, which were highly variable even when familial. Of note, all symptomatic individuals were males. SHFLD3 still remains a mysterious ultra-rare disease and our findings do not answer crucial questions regarding the disease low penetrance, variable expression and heterogeneity. However, we have presented some clinical and molecular aspects that may be helpful in daily diagnostic routine, both dysmorphological and molecular assessment, of patients affected with SHFLD3. Supplementary Information The online version contains supplementary material available at 10.1186/s13023-022-02480-w.
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Affiliation(s)
| | - Anna Sowińska-Seidler
- Department of Medical Genetics, Poznan University of Medical Sciences, Poznan, Poland
| | - Jolanta Wierzba
- Department of Pediatrics and Internal Medicine Nursing, Department of Rare Disorders, Medical University of Gdansk, Gdansk, Poland
| | - Aleksander Jamsheer
- Department of Medical Genetics, Poznan University of Medical Sciences, Poznan, Poland. .,Centers for Medical Genetics GENESIS, Poznan, Poland.
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Sedighzadeh SS, Sedaghat A, Zamani M, Seifi T, Shariati G, Zeighami J, Mazaheri N, Galehdari H. Whole exome sequencing identified a novel frameshift variant in the BHLHA9 in an Iranian family with mesoaxial synostotic syndactyly. Congenit Anom (Kyoto) 2021; 61:220-225. [PMID: 34272776 DOI: 10.1111/cga.12439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 06/04/2021] [Accepted: 06/29/2021] [Indexed: 12/01/2022]
Abstract
Mesoaxial synostotic syndactyly with phalangeal reduction (MSSD) represents a rare non-syndromic defect with an autosomal recessive pattern of inheritance. Sequence variants in the BHLHA9 gene cause MSSD and to date only a few mutations in this gene have been reported. In the present report, we have described a consanguineous Iranian family segregating MSSD in an autosomal recessive manner. The family had two affected siblings showing evidence of camptodactyly in some fingers, complete syndactyly of the 3rd and 4th fingers with synostoses of the corresponding metacarpals, and associated single phalanx in both right and left hand. Whole exome sequencing (WES) followed by segregation analysis using Sanger sequencing identified a novel homozygous frameshift variation [c.74_74delG p.(G25Afs*55)] in the BHLHA9 gene. This has expanded the spectrum of mutations in the BHLHA9 and will facilitate genetic counseling in Iranian families segregating MSSD-related phenotypes.
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Affiliation(s)
- Sahar Sadat Sedighzadeh
- Department of Biology, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran.,Narges Medical Genetics and Prenatal Diagnosis Laboratory, Ahvaz, Khuzestan, Iran
| | - Alireza Sedaghat
- Narges Medical Genetics and Prenatal Diagnosis Laboratory, Ahvaz, Khuzestan, Iran.,Health Research Institute, Diabetes Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Mina Zamani
- Department of Biology, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran.,Narges Medical Genetics and Prenatal Diagnosis Laboratory, Ahvaz, Khuzestan, Iran
| | - Tahere Seifi
- Department of Biology, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran.,Narges Medical Genetics and Prenatal Diagnosis Laboratory, Ahvaz, Khuzestan, Iran
| | - Gholamreza Shariati
- Narges Medical Genetics and Prenatal Diagnosis Laboratory, Ahvaz, Khuzestan, Iran.,Ahvaz Jundishapur University of Medical Sciences, Department of Medical Genetics, Faculty of Medicine, Ahvaz, Iran
| | - Jawaher Zeighami
- Narges Medical Genetics and Prenatal Diagnosis Laboratory, Ahvaz, Khuzestan, Iran
| | - Neda Mazaheri
- Narges Medical Genetics and Prenatal Diagnosis Laboratory, Ahvaz, Khuzestan, Iran
| | - Hamid Galehdari
- Department of Biology, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran.,Narges Medical Genetics and Prenatal Diagnosis Laboratory, Ahvaz, Khuzestan, Iran
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4
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Loss of bhlha9 Impairs Thermotaxis and Formalin-Evoked Pain in a Sexually Dimorphic Manner. Cell Rep 2021; 30:602-610.e6. [PMID: 31968239 DOI: 10.1016/j.celrep.2019.12.041] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 11/18/2019] [Accepted: 12/12/2019] [Indexed: 01/07/2023] Open
Abstract
C-LTMRs are known to convey affective aspects of touch and to modulate injury-induced pain in humans and mice. However, a role for these neurons in temperature sensation has been suggested, but not fully demonstrated. Here, we report that deletion of C-low-threshold mechanoreceptor (C-LTMR)-expressed bhlha9 causes impaired thermotaxis behavior and exacerbated formalin-evoked pain in male, but not female, mice. Positive modulators of GABAA receptors failed to relieve inflammatory formalin pain and failed to decrease the frequency of spontaneous excitatory post-synaptic currents (sEPSCs) selectively in bhlha9 knockout (KO) males. This could be explained by a drastic change in the GABA content of lamina II inner inhibitory interneurons contacting C-LTMR central terminals. Finally, C-LTMR-specific deep RNA sequencing revealed more genes differentially expressed in male than in female bhlha9 KO C-LTMRs. Our data consolidate the role of C-LTMRs in modulation of formalin pain and provide in vivo evidence of their role in the discriminative aspects of temperature sensation.
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P63 modulates the expression of the WDFY2 gene which is implicated in cancer regulation and limb development. Biosci Rep 2020; 39:221381. [PMID: 31789342 PMCID: PMC6914664 DOI: 10.1042/bsr20192114] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 11/15/2019] [Accepted: 11/29/2019] [Indexed: 12/31/2022] Open
Abstract
TP63 is a member of the TP53 gene family, sharing a common gene structure that produces two groups of mRNAs' encoding proteins with different N-terminal regions (ΔN and TA isoforms); both transcripts are also subjected to alternative splicing mechanisms at C-terminus, generating a variety of isoforms. p63 is a master regulator of epidermal development and homoeostasis as well as an important player in tumorigenesis and cancer progression with both oncogenic and tumour suppressive roles. A number of studies have aimed at the identification of p63 target genes, allowing the dissection of the molecular pathways orchestrated by the different isoforms. In the present study we investigated in more detail the p63 responsiveness of the WDFY2 (WD repeat and FYVE domain containing 2) gene, encoding for an endosomal protein identified as a binding partner of the PI-3K/AKT signalling pathway. We showed that overexpression of different p63 isoforms was able to induce WDFY2 expression in TP53-null cells. The p63-dependent transcriptional activation was associated with specific response elements (REs) that have been identified by a bioinformatics tool and validated by yeast- and mammal-based assays. Interestingly, to confirm that WDFY2 belongs to the p63 network of cancer regulation, we analysed the impact of WDFY2 alterations, by showing its frequent deletion in different types of tumours and suggesting its expression level as a prognostic biomarker. Lastly, we identified a chromosomal translocation involving the WDFY2 locus in a patient affected by a rare congenital limb anomaly, indicating WDFY2 as a possible susceptibility gene placed downstream p63 in the network of limb development.
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6
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Montero JA, Lorda-Diez CI, Sanchez-Fernandez C, Hurle JM. Cell death in the developing vertebrate limb: A locally regulated mechanism contributing to musculoskeletal tissue morphogenesis and differentiation. Dev Dyn 2020; 250:1236-1247. [PMID: 32798262 PMCID: PMC8451844 DOI: 10.1002/dvdy.237] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 08/06/2020] [Accepted: 08/06/2020] [Indexed: 12/16/2022] Open
Abstract
Our aim is to critically review current knowledge of the function and regulation of cell death in the developing limb. We provide a detailed, but short, overview of the areas of cell death observed in the developing limb, establishing their function in morphogenesis and structural development of limb tissues. We will examine the functions of this process in the formation and growth of the limb primordia, formation of cartilaginous skeleton, formation of synovial joints, and establishment of muscle bellies, tendons, and entheses. We will analyze the plasticity of the cell death program by focusing on the developmental potential of progenitors prior to death. Considering the prolonged plasticity of progenitors to escape from the death process, we will discuss a new biological perspective that explains cell death: this process, rather than secondary to a specific genetic program, is a consequence of the tissue building strategy employed by the embryo based on the formation of scaffolds that disintegrate once their associated neighboring structures differentiate. We examine the functions of cell death in the formation and growth of the limb primordia. We analyze the plasticity of the cell death program by focusing on the developmental potential of progenitors prior to death. Considering the prolonged plasticity of progenitors to escape from the death process and the absence of defined genetic program in their regulation we propose that cell death is a consequence of the tissue building strategy employed by the embryo regulated by epigenetic factors .
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Affiliation(s)
- Juan A Montero
- Departamento de Anatomía y Biología Celular and IDIVAL, Universidad de Cantabria, Santander, Spain
| | - Carlos I Lorda-Diez
- Departamento de Anatomía y Biología Celular and IDIVAL, Universidad de Cantabria, Santander, Spain
| | | | - Juan M Hurle
- Departamento de Anatomía y Biología Celular and IDIVAL, Universidad de Cantabria, Santander, Spain
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Díaz-González F, Parrón-Pajares M, Barcia-Ramirez A, Heath KE. First case of compound heterozygous BHLHA9 variants in mesoaxial synostotic syndactyly with phalangeal reduction. Am J Med Genet A 2020; 182:628-631. [PMID: 31912643 DOI: 10.1002/ajmg.a.61480] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 12/22/2019] [Indexed: 12/23/2022]
Abstract
Mesoaxial synostotic syndactyly with phalangeal reduction (MSSD) is an extremely rare autosomal recessive limb abnormality characterized by the fusion of third and fourth fingers. To date, only homozygous missense and frameshift mutations have been reported in BHLHA9 associated to MSSD. In this study, we report a patient who presented with clinical and radiological features of MSSD. A customized skeletal dysplasia NGS panel revealed the presence of two novel compounds heterozygous variants in BHLHA9: NM_001164405.1: c.[226A>T][269G>C]; p.[(Lys76*)][(Arg90Pro)]. Thus, this is the first case of MSSD in a nonconsanguineous family.
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Affiliation(s)
- Francisca Díaz-González
- Institute of Medical & Molecular Genetics (INGEMM), Hospital Universitario La Paz, Universidad Autónoma de Madrid, IdiPAZ, Madrid, Spain
- Skeletal dysplasia Multidisciplinary Unit (UMDE), Hospital Universitario La Paz, Madrid, Spain
| | - Manuel Parrón-Pajares
- Skeletal dysplasia Multidisciplinary Unit (UMDE), Hospital Universitario La Paz, Madrid, Spain
- Department of Radiology, Hospital Universitario la Paz, Madrid, Spain
| | - Ana Barcia-Ramirez
- Department of Pediatrics, Hospital Universitario Virgen de Valme, Sevilla, Spain
| | - Karen E Heath
- Institute of Medical & Molecular Genetics (INGEMM), Hospital Universitario La Paz, Universidad Autónoma de Madrid, IdiPAZ, Madrid, Spain
- Skeletal dysplasia Multidisciplinary Unit (UMDE), Hospital Universitario La Paz, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER, U753), Instituto Carlos III, Madrid, Spain
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8
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Khan F, Arshad A, Majeed AI, Ullah A, Ahmad W. A novel frameshift variant in BHLHA9 underlies mesoaxial synostotic syndactyly associated with postaxial polydactyly. Eur J Med Genet 2019; 62:103688. [DOI: 10.1016/j.ejmg.2019.103688] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 05/26/2019] [Accepted: 05/28/2019] [Indexed: 10/26/2022]
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9
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Paththinige CS, Sirisena ND, Escande F, Manouvrier S, Petit F, Dissanayake VHW. Split hand/foot malformation with long bone deficiency associated with BHLHA9 gene duplication: a case report and review of literature. BMC MEDICAL GENETICS 2019; 20:108. [PMID: 31200655 PMCID: PMC6570964 DOI: 10.1186/s12881-019-0839-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 06/03/2019] [Indexed: 12/11/2022]
Abstract
Background Split hand/foot malformation (SHFM) is a group of congenital skeletal disorders which may occur either as an isolated abnormality or in syndromic forms with extra-limb manifestations. Chromosomal micro-duplication or micro-triplication involving 17p13.3 region has been described as the most common cause of split hand/foot malformation with long bone deficiency (SHFLD) in several different Caucasian and Asian populations. Gene dosage effect of the extra copies of BHLHA9 gene at this locus has been implicated in the pathogenesis of SHFLD. Case presentation The proband was a female child born to non-consanguineous parents. She was referred for genetic evaluation of bilateral asymmetric ectrodactyly involving both hands and right foot along with right tibial hemimelia. The right foot had fixed clubfoot deformity with only 2 toes. The mother had bilateral ectrodactyly involving both hands, but the rest of the upper limbs and both lower limbs were normal. Neither of them had any other congenital malformations or neurodevelopmental abnormalities. Genetic testing for rearrangement of BHLHA9 gene by quantitative polymerase chain reaction confirmed the duplication of the BHLHA9 gene in both the proband and the mother. Conclusions We report the first Sri Lankan family with genetic diagnosis of BHLHA9 duplication causing SHFLD. This report along with the previously reported cases corroborate the possible etiopathogenic role of BHLHA9 gene dosage imbalances in SHFM and SHFLD across different populations.
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Affiliation(s)
- Chamara Sampath Paththinige
- Human Genetics Unit, Faculty of Medicine, University of Colombo, Kynsey Road, Colombo, 00800, Sri Lanka. .,Faculty of Medicine and Allied Sciences, Rajarata University of Sri Lanka, Saliyapura, Anuradhapura, 50008, Sri Lanka.
| | | | - Fabienne Escande
- Laboratoire de Biochimie et Oncologie Moléculaire, CHU Lille, F-59000, Lille, France
| | - Sylvie Manouvrier
- Clinique de Génétique Guy Fontaine, CHU Lille, F-59000, Lille, France
| | - Florence Petit
- Clinique de Génétique Guy Fontaine, CHU Lille, F-59000, Lille, France
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10
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Ullah A, Ali RH, Majeed AI, Liaqat K, Shah PW, Khan B, Bilal M, Umair M, Ahmad W. A novel insertion and deletion mutation in the BHLHA9 underlies polydactyly and mesoaxial synostotic syndactyly with phalangeal reduction. Eur J Med Genet 2019; 62:278-281. [DOI: 10.1016/j.ejmg.2018.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 07/23/2018] [Accepted: 08/09/2018] [Indexed: 10/28/2022]
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11
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Al-Qattan MM. A Review of the Genetics and Pathogenesis of Syndactyly in Humans and Experimental Animals: A 3-Step Pathway of Pathogenesis. BIOMED RESEARCH INTERNATIONAL 2019; 2019:9652649. [PMID: 31637260 PMCID: PMC6766129 DOI: 10.1155/2019/9652649] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 08/23/2019] [Accepted: 09/01/2019] [Indexed: 12/30/2022]
Abstract
Embryology of normal web space creation and the genetics of syndactyly in humans and experimental animals are well described in the literature. In this review, the author offers a 3-step pathway of pathogenesis for syndactyly. The first step is initiated either by the overactivation of the WNT canonical pathway or the suppression of the Bone Morphogenetic Protein (BMP) canonical pathway. This leads to an overexpression of Fibroblast Growth Factor 8 (FGF8). The final step is the suppression of retinoic acid in the interdigital mesenchyme leading to suppression of both apoptosis and extracellular matrix (ECM) degradation, resulting in syndactyly.
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Affiliation(s)
- Mohammad M Al-Qattan
- Professor of Hand Surgery, King Saud University, Riyadh, Saudi Arabia
- King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
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12
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Kantaputra PN, Carlson BM. Genetic regulatory pathways of split-hand/foot malformation. Clin Genet 2018; 95:132-139. [PMID: 30101460 DOI: 10.1111/cge.13434] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 08/07/2018] [Indexed: 12/13/2022]
Abstract
Split-hand/foot malformation (SHFM) is caused by mutations in TP63, DLX5, DLX6, FGF8, FGFR1, WNT10B, and BHLHA9. The clinical features of SHFM caused by mutations of these genes are not distinguishable. This implies that in normal situations these SHFM-associated genes share an underlying regulatory pathway that is involved in the development of the central parts of the hands and feet. The mutations in SHFM-related genes lead to dysregulation of Fgf8 in the central portion of the apical ectodermal ridge (AER) and subsequently lead to misexpression of a number of downstream target genes, failure of stratification of the AER, and thus SHFM. Syndactyly of the remaining digits is most likely the effects of dysregulation of Fgf-Bmp-Msx signaling on apoptotic cell death. Loss of digit identity in SHFM is hypothesized to be the effects of misexpression of HOX genes, abnormal SHH gradient, or the loss of balance between GLI3A and GLI3R. Disruption of canonical and non-canonical Wnt signaling is involved in the pathogenesis of SHFM. Whatever the causative genes of SHFM are, the mutations seem to lead to dysregulation of Fgf8 in AER cells of the central parts of the hands and feet and disruption of Wnt-Bmp-Fgf signaling pathways in AER.
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Affiliation(s)
- Piranit N Kantaputra
- Center of Excellence in Medical Genetics Research, Chiang Mai University, Chiang Mai, Thailand.,Division of Pediatric Dentistry, Department of Orthodontics and Pediatric Dentistry, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand.,Dentaland Clinic, Chiang Mai, Thailand
| | - Bruce M Carlson
- Department of Anatomy and Cell Biology, University of Michigan, Ann Arbor, Michigan
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13
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Kataoka K, Matsushima T, Ito Y, Sato T, Yokoyama S, Asahara H. Bhlha9 regulates apical ectodermal ridge formation during limb development. J Bone Miner Metab 2018; 36:64-72. [PMID: 28324176 PMCID: PMC6324935 DOI: 10.1007/s00774-017-0820-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 01/25/2017] [Indexed: 10/19/2022]
Abstract
Split hand/foot malformation (SHFM) and SHFM combined with long-bone deficiency (SHFLD) are congenital dysgeneses of the limb. Although six different loci/mutations (SHFM1-SHFM6) have been found from studies on families with SHFM, the causes and associated pathogenic mechanisms for a large number of patients remain unidentified. On the basis of the identification of a duplicated gene region involving BHLHA9 in some affected families, BHLHA9 was identified as a novel SHFM/SHFLD-related gene. Although Bhlha9 is predicted to participate in limb development as a transcription factor, its precise function is unclear. Therefore, to study its physiological function, we generated a Bhlha9-knockout mouse and investigated gene expression and the associated phenotype in the limb bud. Bhlha9-knockout mice showed syndactyly and poliosis in the limb. Moreover, some apical ectodermal ridge (AER) formation related genes, including Trp63, exhibited an aberrant expression pattern in the limb bud of Bhlha9-knockout mice; TP63 (Trp63) was regulated by Bhlha9 on the basis of in vitro analysis. These observations suggest that Bhlha9 regulates AER formation during limb/finger development by regulating the expression of some AER-formation-related genes and abnormal expression of Bhlha9 leads to SHFM and SHFLD via dysregulation of AER formation and associated gene expression.
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Affiliation(s)
- Kensuke Kataoka
- Department of Systems BioMedicine, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Takahide Matsushima
- Department of Systems BioMedicine, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Yoshiaki Ito
- Department of Systems BioMedicine, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Tempei Sato
- Department of Systems BioMedicine, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Shigetoshi Yokoyama
- Department of Systems Biomedicine, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-0074, Japan
| | - Hiroshi Asahara
- Department of Systems BioMedicine, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
- Department of Systems Biomedicine, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-0074, Japan.
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14
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Khan A, Wang R, Han S, Ahmad W, Zhang X. A novel homozygous missense mutation in BHLHA9 causes mesoaxial synostotic syndactyly with phalangeal reduction in a Pakistani family. Hum Genome Var 2017; 4:17054. [PMID: 29263794 PMCID: PMC5729216 DOI: 10.1038/hgv.2017.54] [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: 08/15/2017] [Revised: 10/10/2017] [Accepted: 10/22/2017] [Indexed: 11/10/2022] Open
Abstract
Mesoaxial synostotic syndactyly with phalangeal reduction (MSSD) is a rare non-syndromic limb malformation with autosomal recessive inheritance. To date, only a few affected families with MSSD who had BHLHA9 mutations have been reported. The present report describes a consanguineous Pakistani family with five affected individuals with MSSD who exhibited an autosomal recessive pattern. Genotyping followed by Sanger sequencing was performed, and we identified a novel homozygous missense mutation (c.311T>C, p.Ile104Thr) in the BHLHA9 gene. This finding expands the spectrum of known mutations in the BHLHA9 gene that cause MSSD.
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Affiliation(s)
- Amjad Khan
- The Research Center for Medical Genomics, China Medical University, Shenyang, China.,McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China.,Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Rongrong Wang
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Shirui Han
- The Research Center for Medical Genomics, China Medical University, Shenyang, China.,McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Wasim Ahmad
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Xue Zhang
- The Research Center for Medical Genomics, China Medical University, Shenyang, China.,McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
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15
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Carter TC, Sicko RJ, Kay DM, Browne ML, Romitti PA, Edmunds ZL, Liu A, Fan R, Druschel CM, Caggana M, Brody LC, Mills JL. Copy-number variants and candidate gene mutations in isolated split hand/foot malformation. J Hum Genet 2017; 62:877-884. [PMID: 28539665 PMCID: PMC5612852 DOI: 10.1038/jhg.2017.56] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 04/19/2017] [Accepted: 04/25/2017] [Indexed: 12/27/2022]
Abstract
Split hand/foot malformation (SHFM) is a congenital limb deficiency with missing or shortened central digits. Some SHFM genes have been identified but the cause of many SHFM cases is unknown. We used single-nucleotide polymorphism (SNP) microarray analysis to detect copy-number variants (CNVs) in 25 SHFM cases without other birth defects from New York State (NYS), prioritized CNVs absent from population CNV databases, and validated these CNVs using quantitative real-time polymerase chain reaction (qPCR). We tested for the validated CNVs in seven cases from Iowa using qPCR, and also sequenced 36 SHFM candidate genes in all the subjects. Seven NYS cases had a potentially deleterious variant: two had a p.R225H or p.R225L mutation in TP63, one had a 17q25 microdeletion, one had a 10q24 microduplication and three had a 17p13.3 microduplication. In addition, one Iowa case had a de novo 10q24 microduplication. The 17q25 microdeletion has not been reported previously in SHFM and included two SHFM candidate genes (SUMO2 and GRB2), while the 10q24 and 17p13.3 CNVs had breakpoints within genomic regions that contained putative regulatory elements and a limb development gene. In SHFM pathogenesis, the microdeletion may cause haploinsufficiency of SHFM genes and/or deletion of their regulatory regions, and the microduplications could disrupt regulatory elements that control transcription of limb development genes.
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Affiliation(s)
- Tonia C. Carter
- Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 6710B Building, Room 3117, Bethesda, MD 20892, USA
| | - Robert J. Sicko
- Wadsworth Center, New York State Department of Health, 120 New Scotland Avenue, Albany, NY 12201-2002, USA
| | - Denise M. Kay
- Wadsworth Center, New York State Department of Health, 120 New Scotland Avenue, Albany, NY 12201-2002, USA
| | - Marilyn L. Browne
- Congenital Malformations Registry, New York State Department of Health, Empire State Plaza-Corning Tower, Albany, NY 12237, USA
- University at Albany School of Public Health, One University Place, Rensselaer, NY 12144, USA
| | - Paul A. Romitti
- Department of Epidemiology, College of Public Health, The University of Iowa, 145 N. Riverside Drive, Iowa City, IA 52242, USA
| | - Zoë L. Edmunds
- Wadsworth Center, New York State Department of Health, 120 New Scotland Avenue, Albany, NY 12201-2002, USA
| | - Aiyi Liu
- Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 6710B Building, Room 3117, Bethesda, MD 20892, USA
| | - Ruzong Fan
- Department of Biostatistics, Bioinformatics, and Biomathematics, 4000 Reservoir Road NW, Building D-180, Georgetown University Medical Center, Washington DC 20057, USA
| | - Charlotte M. Druschel
- Congenital Malformations Registry, New York State Department of Health, Empire State Plaza-Corning Tower, Albany, NY 12237, USA
| | - Michele Caggana
- Wadsworth Center, New York State Department of Health, 120 New Scotland Avenue, Albany, NY 12201-2002, USA
| | - Lawrence C. Brody
- Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Building 50, 50 South Drive, MSC 8004, Bethesda, MD 20892, USA
| | - James L. Mills
- Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 6710B Building, Room 3117, Bethesda, MD 20892, USA
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16
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Abstract
The limb is a commonly used model system for developmental biology. Given the need for precise control of complex signalling pathways to achieve proper patterning, the limb is also becoming a model system for gene regulation studies. Recent developments in genomic technologies have enabled the genome-wide identification of regulatory elements that control limb development, yielding insights into the determination of limb morphology and forelimb versus hindlimb identity. The modulation of regulatory interactions - for example, through the modification of regulatory sequences or chromatin architecture - can lead to morphological evolution, acquired regeneration capacity or limb malformations in diverse species, including humans.
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Affiliation(s)
- Florence Petit
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, California 94158, USA.,University of Lille, CHU Lille, EA 7364-RADEME, F-59000 Lille, France
| | - Karen E Sears
- School of Integrative Biology, Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, USA
| | - Nadav Ahituv
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, California 94158, USA.,Institute for Human Genetics, University of California San Francisco, California 94158, USA
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17
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Fusco C, Nittis PD, Alfaiz AA, Pellico MT, Augello B, Malerba N, Zelante L, Reymond A, Merla G. A New Split Hand/Foot Malformation with Long Bone Deficiency Familial Case. J Pediatr Genet 2016; 6:98-102. [PMID: 28496997 DOI: 10.1055/s-0036-1588029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 07/19/2016] [Indexed: 12/16/2022]
Abstract
Split hand/foot malformation with long bone deficiency (SHFLD) is a congenital limb anomaly where hands and/or feet cleft and syndactyly are associated with long bone defects, usually involving the tibia. Previously published data reported that 17p13.3 chromosomal duplication, including the BHLHA9 gene, has been associated with the distinct entity, termed SHFLD3 (OMIM 612576), inherited as an autosomal dominant trait. Here, we present a family with three members affected by SHFLD harboring BHLHA9 duplication. We exploited in vitro differentiation system to promote proband's skin fibroblasts toward osteoblastic lineage, and we observed a slight but consistent delay in the mineralization pattern. This result possibly suggests an impairment of the osteogenic process in the affected members.
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Affiliation(s)
- Carmela Fusco
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Pasquelena De Nittis
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy.,Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Ali Abdullah Alfaiz
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland.,Bioinformatics Core Facility, Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Maria Teresa Pellico
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Bartolomeo Augello
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Natascia Malerba
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Leopoldo Zelante
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Alexandre Reymond
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Giuseppe Merla
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
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18
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Spatiotemporal distribution of proliferation, proapoptotic and antiapoptotic factors in the early human limb development. Acta Histochem 2016; 118:527-36. [PMID: 27282649 DOI: 10.1016/j.acthis.2016.05.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 05/19/2016] [Accepted: 05/24/2016] [Indexed: 12/28/2022]
Abstract
Involvement of proliferation and apoptosis in the human limb development was analyzed electronmicroscopically and immunohistochemically in histological sections of 8 human embryos, 4(th) -10(th) week old, using apoptotic (caspase-3, AIF, BAX), anti-apoptotic (Bcl-2) and proliferation (Ki-67) markers, and TUNEL method. The data were analyzed by Mann-Whitney test, Kruskal-Wallis and Dunn's post hoc test. Initially, developing human limbs consisted of mesenchymal core and surface ectoderm with apical ectodermal ridge (AER). During progression of development, strong proliferation activity gradually decreased in the mesenchyme (from 78% to 68%) and in the epithelium (from 62% to 42%), while in the differentiating finger cartilages proliferation was constantly low (26-7%). Apoptotic caspase-3 and AIF-positive cells characterized mesenchyme and AER at earliest stages, while during digit separation they appeared in interdigital mesenchyme as well. Strong Bcl-2 expression was observed in AER, subridge mesenchyme and phalanges, while BAX expression charaterized limb areas undergoing apoptosis. Ultrastructurally, proliferating cells showed mitotic figures, while apoptotic cells were characterized by nuclear fragmentation. Macrophages were observed around the apoptotic cells. We suggest that intense proliferation enables growth and elongation of human limb primordia, and differential growth of digits. Both caspase-3 and AIF-dependant pathways of cell death control the extent of AER and numer of cells in the subridge mesenchyme at earliest developmental stages, as well as process of digit separation at later stages of limb development. Spatio-temporal co-expresson of Bcl-2 and BAX indicates their role in suppression of apoptosis and selective stimulation of growth during human limb morphogenesis.
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19
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Phadke SR, Kar A, Bhowmik AD, Dalal A. Complex Camptosynpolydactyly and Mesoaxial synostotic syndactyly with phalangeal reduction are allelic disorders. Am J Med Genet A 2016; 170:1622-5. [PMID: 27041388 DOI: 10.1002/ajmg.a.37643] [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: 12/22/2015] [Accepted: 03/20/2016] [Indexed: 11/06/2022]
Abstract
Complex Camptosynpolydactyly is an autosomal recessive disorder characterized by complex hand deformities described earlier by us in a consanguineous family. We report on identification of mutations in BHLHA9 gene in this condition. Our results indicate that Complex Camptosynpolydactyly and Mesoaxial synostotic syndactyly with phalangeal reduction (MSSD) are likely to be allelic disorders. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Shubha R Phadke
- Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
| | - Anjana Kar
- Diagnostics Division, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India.,Graduate Studies, Manipal University, Manipal, India
| | - Aneek Das Bhowmik
- Diagnostics Division, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
| | - Ashwin Dalal
- Diagnostics Division, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
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20
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Malik S, Percin FE, Bornholdt D, Albrecht B, Percesepe A, Koch MC, Landi A, Fritz B, Khan R, Mumtaz S, Akarsu NA, Grzeschik KH. Mutations affecting the BHLHA9 DNA-binding domain cause MSSD, mesoaxial synostotic syndactyly with phalangeal reduction, Malik-Percin type. Am J Hum Genet 2014; 95:649-59. [PMID: 25466284 DOI: 10.1016/j.ajhg.2014.10.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 10/27/2014] [Indexed: 12/25/2022] Open
Abstract
Mesoaxial synostotic syndactyly, Malik-Percin type (MSSD) (syndactyly type IX) is a rare autosomal-recessive nonsyndromic digit anomaly with only two affected families reported so far. We previously showed that the trait is genetically distinct from other syndactyly types, and through autozygosity mapping we had identified a locus on chromosome 17p13.3 for this unique limb malformation. Here, we extend the number of independent pedigrees from various geographic regions segregating MSSD to a total of six. We demonstrate that three neighboring missense mutations affecting the highly conserved DNA-binding region of the basic helix-loop-helix A9 transcription factor (BHLHA9) are associated with this phenotype. Recombinant BHLHA9 generated by transient gene expression is shown to be located in the cytoplasm and the cell nucleus. Transcription factors 3, 4, and 12, members of the E protein (class I) family of helix-loop-helix transcription factors, are highlighted in yeast two-hybrid analysis as potential dimerization partners for BHLHA9. In the presence of BHLHA9, the potential of these three proteins to activate expression of an E-box-regulated target gene is reduced considerably. BHLHA9 harboring one of the three substitutions detected in MSSD-affected individuals eliminates entirely the transcription activation by these class I bHLH proteins. We conclude that by dimerizing with other bHLH protein monomers, BHLHA9 could fine tune the expression of regulatory factors governing determination of central limb mesenchyme cells, a function made impossible by altering critical amino acids in the DNA binding domain. These findings identify BHLHA9 as an essential player in the regulatory network governing limb morphogenesis in humans.
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Affiliation(s)
- Sajid Malik
- Zentrum fuer Humangenetik, Philipps-Universitaet Marburg, 35033 Marburg, Germany; Department of Animal Sciences, Human Genetics Program, Faculty of Biological Sciences, Quaid-i-Azam University, 45320 Islamabad, Pakistan
| | - Ferda E Percin
- Department of Medical Genetics, Faculty of Medicine, Gazi University, Besevler, 06500 Ankara, Turkey
| | - Dorothea Bornholdt
- Zentrum fuer Humangenetik, Philipps-Universitaet Marburg, 35033 Marburg, Germany
| | - Beate Albrecht
- Institut fuer Humangenetik, Universitaetsklinikum Essen, Universitaet Duisburg-Essen, 45147 Essen, Germany
| | - Antonio Percesepe
- Department of Mother and Child, Medical Genetics Unit, University Hospital of Modena, 41124 Modena, Italy
| | - Manuela C Koch
- Zentrum fuer Humangenetik, Philipps-Universitaet Marburg, 35033 Marburg, Germany
| | - Antonio Landi
- Department of Hand Surgery and Microsurgery, University Hospital of Modena, 41100 Modena, Italy
| | - Barbara Fritz
- Zentrum fuer Humangenetik, Philipps-Universitaet Marburg, 35033 Marburg, Germany
| | - Rizwan Khan
- Department of Animal Sciences, Human Genetics Program, Faculty of Biological Sciences, Quaid-i-Azam University, 45320 Islamabad, Pakistan
| | - Sara Mumtaz
- Department of Animal Sciences, Human Genetics Program, Faculty of Biological Sciences, Quaid-i-Azam University, 45320 Islamabad, Pakistan
| | - Nurten A Akarsu
- Department of Medical Genetics, Gene Mapping Laboratory, Hacettepe University Medical Faculty, Sihhiye, 06100 Ankara, Turkey
| | - Karl-Heinz Grzeschik
- Zentrum fuer Humangenetik, Philipps-Universitaet Marburg, 35033 Marburg, Germany.
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