Detection of Connexion 26 GENE (GJB2) Mutations in Cases of Congenital Non Syndromic Deafness

Abstract

Hearing loss is most common form of genetic hearing disorder. Non-syndromic sensory neural autosomal recessive deafness (NSRD) is the most common form of genetic hearing loss. Mutations in GJB2 gene, which encodes the connexin 26 protein, are major cause of NSRD. The aim of this study is directed towards the mutations caused along the connexin 26 gene using blood samples from nonsyndromic deaf children. The study was conducted on 36 congenitally hearing impaired children who visited to our department with complains of hearing loss and reduced speech and whose age was\10 years with no other congenital anomaly. After a thorough history, clinical examination and all audiological and radiological assessment, blood samples are collected and DNA extraction, PCR and sequencing were done for further genetic analysis. Annotated and documented autosomal recessive (pathogenic) mutations were observed in 57 % of NSRD cases. The frequency of pathogenic mutation was commonest for Ins G between nucleotide 30-35 (40 % of cases) followed by Del T at nucleotide 59(20 % of cases).These two common mutations (singly or doubly) were present in 51.4 % of cases. Present study helps to screen the families with hearing impaired children, which will facilitate the development of strategies for diagnosis and treatment of these common genetic disorders.

Update of spectrum c.35delG and c.‐23+1G>A mutations on the GJB2 gene in individuals with autosomal recessive nonsyndromic hearing loss

“…The carrier frequency of c.35delG mutation is high in Europe and among Americans of European ancestry (Gasparini et al., ; Kelley et al., ). However, the high frequency of c.35delG mutation in Caucasian populations is possibly the result of a founder effect rather than a mutational hot spot (Banjara, Mungutwar, Swarnkar, & Patra, ; Mustapha et al., ; Zoidl, & Dermietzel, ). The frequency of the c.35delG mutation differs in the Iranian population, with a higher slope of mutation frequency from south to north and east to west (Bonyadi, Fotouhi, & Esmaeili, ; Chaleshtori et al., ; Galehdari, Foroughmand, Soorki, and Mohammadian, ; Najmabadi et al., ; Tabatabaiefar et al., ) and a frequency that is similar to that reported in neighboring Turkey and Pakistan.…”

Mutations in GJB2 as Major Causes of Autosomal Recessive Non-Syndromic Hearing Loss: First Report of c.299-300delAT Mutation in Kurdish Population of Iran

“…Variation in frequency between different ethnic groups can be the result of human migrations; the high prevalence of the c.35delG mutation in Caucasian populations is possibly the result of a founder effect rather than a mutational hot spot [25]. The Iranian population is composed of various ethnic groups; the prevalence of this mutation differs between Iranian population with a higher slope of mutation frequency from south-tonorth (0% to 33%), and from east-to-west (8% to 8.8%) [12,15].…”

Recent Advancements in the Regeneration of Auditory Hair Cells and Hearing Restoration

“…For many ethnic populations, the most prevalent form of genetic deafness is caused by recessive mutations in the gene for a gap junction protein, i.e., beta 2, 26 kDa (GJB2), which is also known as connexin 26 (Cx26; Banjara et al, 2016 ; Du et al, 2016 ; Mielczarek et al, 2016 ; Moctar et al, 2016 ; Xia H. et al, 2016 ). A gene delivery system has been used to rescue hearing in a mouse model of GJB2 deletion (Iizuka et al, 2015 ).…”