Genetics of hereditary hearing loss in east Iran population: A systematic review of GJB2 mutations
INTRACTABLE & RARE DISEASES RESEARCH
Authors: Koohiyan, Mahbobeh; Azadegan-Dehkordi, Fatemeh; Koohian, Farideh; Abolhasani, Marziye; Hashemzadeh-Chaleshtori, Morteza
Mutations in the GJB2 gene are the most common cause of pre-lingual hearing loss (HL) worldwide. Previous studies have shown the frequency of GJB2 mutations to be 16% in Iran, but varies among different ethnic groups. Here, we have reviewed results from previous published mutation reports to provide a comprehensive collection of data for GJB2 mutations and HL in eastern Iran. We conducted a systematic literature review of PubMed, Google Scholar, Web of Science, and Science Direct databases for articles published before March, 2019. The literature search was performed by 2 independent researchers. The primary data of these studies including the number of samples, allelic frequency, and so on were extracted. Six studies involving 812 unrelated families from four different eastern provinces were included and analyzed for the type and prevalence of GJB2 mutations. A total of 19 different genetic variants were detected. GJB2 mutations were 8.8% in the studied eastern provinces, which was lower than that reported in northern populations of Iran. Moreover, a gradient in the frequency of GJB2 mutations from north to south Iran was observed. c.35delG was the most frequent mutation, accounting for 48.5% % of the populations studied. However, this mutation was absent in the Baluchi population. This review shows that particular rare mutations are frequent in some Iranian ethnic groups, and should be considered for genetic counselling.
Sensorial Hearing Loss Secondary to GJB2 Mutation
PROCEEDINGS OF NATIONAL ENT, HEAD AND NECK SURGERY CONFERENCE
Authors: Butnaru, Corina; Meriacre, Tatiana; Cumpata, Adeline; Cobzeanu, Bogdan; Cozma, Sebastian; Necula, Violeta; Martu, Cristian; Birkenhaeger, Ralf
Deafness is a disability that affects millions of people all over the world. It is a major burden for health care services worldwide. Hearing loss occurs in 1:1000 neonates and the cause are genetic and present at birth in approximately 50% of cases. In about 75% of cases the hearing loss appears isolated (non-syndromic). The most frequent non-syndromic hearing loss is caused by mutations in the connexin 26 gene. The present study has assessed the most frequent mutation in the GJB2 gene in children with severe and profound deafness in Romania. Normal hearing at birth is a prerequisite to acquired speech. Genetic analysis has an important role in the diagnosis of deafness. The results have to be accurately interpreted and the family has to be correctly informed to make sure that they understand the importance of the information.