High frequency of connexin26 (GJB2) mutations associated with nonsyndromic hearing loss in the population of Kerala, India.

OBJECTIVE: Mutations in connexin 26 gene (GJB2) are the most common cause of hearing loss in different populations. The aim of our study was to determine the prevalence of GJB2 mutations in the population of Kerala, India. METHODS: This study was conducted on the genomic DNA of 86 affected subjects and their relatives from 59 families of Kerala, India. Mutation detection was done by sequencing and PCR-RFLP. RESULTS: 36% of the probands had mutations in the GJB2 gene. We found that 45% (15/33) of the families that had a family history of deafness had mutations in GJB2 gene. Two different mutations were identified. W24X mutation was detected in 32.5% of the affected patients. Analysis of control samples revealed a carrier frequency of 0.0357 for this mutation. The estimation of haplotype frequency revealed that there was a significant association between the W24X mutation and the haplotype in this region with respect to the markers, D13S143 and D13S175 suggesting a founder effect for this mutation in this population. A novel mutation, R32L was detected in 3.5% of the affected patients. Structural prediction revealed that this mutation alters the helical structure of the first transmembrane domain of GJB2 protein resulting in defective gap junctions. CONCLUSION: Mutations in connexin26 is responsible for 36% of non-syndromic sensorineural deafness in the population of Kerala, India.

Rapid detection and characterization of Chikungunya virus by RT-PCR in febrile patients from Kerala, India.

There has been a resurgence and prevalence of fever with symptoms of Chikungunya (CHIK) and increased death toll in Kerala, the southern-most state of India. The objective of this study was to develop a rapid detection method to determine the presence of CHIK- virus in the serum samples collected from febrile patients in Kerala, India. Serum specimens were analyzed for CHIK viral RNA by RT-PCR using primers specific for nsP1 and E1 genes. Five out of twenty clinical samples were positive for CHIK virus. The partial sequences of the E1 and nsP1 genes of the strain, IndKL01 were highly similar to the Reunion strains and the recently isolated Indian strains. A novel substitution, A148V, was detected in the E1 gene of the isolate, IndKL02. The detection procedure used in this study was simple, sensitive and rapid (less than 4 hr). This result suggests that CHIK viruses similar to the Reunion strains, which had resulted in high morbidity and mortality rates, may have caused the recent Chikungunya outbreak in India. The effect of the variant, E1-A148V, in the virulence and the rate of transmission of the virus deserves further investigation.