Identification of Novel CDH23 Variants Causing Moderate to Profound Progressive Nonsyndromic Hearing Loss

Genes

SelwaA. F. Al-Hazzaa¹  Faiqa Imtiaz²  Lina Elbaik²  Khushnooda Ramzan²  NoufS. Al-Numair²  Mohammed Al-Owain³  Nadia Sakati³  Sarah Al-Ageel⁴ 

[1] College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia;Department of Genetics, King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia;Department of Medical Genetics, King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia;Department of Otolaryngology Head and Neck Surgery, King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia;

关键词: nonsyndromic hearing loss;    DFNB12;    CDH23;    whole exome sequencing;    missense variants;    phenotypic variability;   

DOI  :  10.3390/genes11121474

来源: DOAJ

【 摘 要 】

Mutant alleles of CDH23, a gene that encodes a putative calcium-dependent cell-adhesion glycoprotein with multiple cadherin-like domains, are responsible for both recessive DFNB12 nonsyndromic hearing loss (NSHL) and Usher syndrome 1D (USH1D). The encoded protein cadherin 23 (CDH23) plays a vital role in maintaining normal cochlear and retinal function. The present study’s objective was to elucidate the role of DFNB12 allelic variants of CDH23 in Saudi Arabian patients. Four affected offspring of a consanguineous family with autosomal recessive moderate to profound NSHL without any vestibular or retinal dysfunction were investigated for molecular exploration of genes implicated in hearing impairment. Parallel to this study, we illustrate some possible pitfalls that resulted from unexpected allelic heterogeneity during homozygosity mapping due to identifying a shared homozygous region unrelated to the disease locus. Compound heterozygous missense variants (p.(Asp918Asn); p.(Val1670Asp)) in CDH23 were identified in affected patients by exome sequencing. Both the identified missense variants resulted in a substitution of the conserved residues and evaluation by multiple in silico tools predicted their pathogenicity and variable disruption of CDH23 domains. Three-dimensional structure analysis of human CDH23 confirmed that the residue Asp918 is located at a highly conserved DXD peptide motif and is directly involved in “Ca²⁺” ion contact. In conclusion, our study identifies pathogenic CDH23 variants responsible for isolated moderate to profound NSHL in Saudi patients and further highlights the associated phenotypic variability with a genotypic hierarchy of CDH23 mutations. The current investigation also supports the application of molecular testing in the clinical diagnosis and genetic counseling of hearing loss.

【 授权许可】

Unknown