This study aimed to identify different mutations in the GJB2 gene in patients with severe to profound nonsyndromic sensorineural hearing loss of putative genetic origin, and who were negative or heterozygote for the 35delG mutation.
Additional genetic changes in the regulatory region of the human GJB2 gene encoding the gap junction protein (Connexin 26) may contribute to sensorineural hearing loss.
Alterations of the Cx26 gene account for a large proportion of cases of congenital non-syndromic sensorineural deafness, so it seems appropriate to extend the molecular analysis even to subjects with mild or moderate prelingual hearing impairment of unknown cause.
We confirm that the p. G130V variant of the GJB2 gene is causative of autosomal dominant form of SNHL, although it is not always associated with the presence of skin diseases.
It has been demonstrated that distinct germline mutations within six connexin (Cx) genes GJB2 (Cx26), GJB6 (Cx30), GJB3 (Cx31), GJA1 (Cx43), GJB4 (Cx30.3), and GJB5 (Cx31.1), may cause sensorineural hearing loss and various skin disease phenotypes.
The overall prevalence of SLC26A4 mutations in nonsyndromic childhood sensorineural hearing loss (11.2%, 37/330) were determined by sequencing of SLC26A4 in 330 hearing impaired children who did not undergo inner ear radiologic imaging prior to their genetic test.
Eleven affected members of a large German-American family segregating recessively inherited, congenital, non-syndromic sensorineural hearing loss (SNHL) were found to be homozygous for the common 35delG mutation of GJB2, the gene encoding the gap junction protein Connexin 26.
1) Diagnostic yields of GJB2 screens, imaging, and laboratory results per SNHL category; 2) Cost analysis comparing a sequential versus a simultaneous testing approach.
Here we present the results of the first study of GJB2 and three mitochondrial mutations among two groups of Belarusian inhabitants: native people with normal hearing (757 persons) and 391 young patients with non-syndromic SNHL.
Using denaturing high-performance liquid chromatography combined with direct sequencing and cloning-sequencing, Japanese patients with prelingual (N = 54) or postlingual (N = 80) sensorineural hearing loss not having pathogenic mutations of m.1555A > G and m.3243A > G nor GJB2 were subjected to mutational analysis of mtDNA genes (12S rRNA, tRNALeu(UUR), tRNASer(UCN), tRNALys, tRNAHis, tRNASer(AGY), and tRNAGlu).
The G45E mutation was not reported previously in Caucasian patients but was the third most common GJB2 mutation (16% of disease alleles) in Japanese patients with autosomal recessive non-syndromic HL.
Cx 30 deletion analysis is recommended for all individuals with nonsyndromic SNHL following Cx 26 sequencing that does not demonstrate two recessive mutations.