Twenty percent of all childhood deafness is due to mutations in the GJB2 gene (Connexin 26). The aim of our study was to determine the prevalence and spectrum of GJB2 mutations in childhood deafness in Malaysia. We analyzed the GJB2 gene in 51 deaf students from Sekolah Pendidikan Khas Alor Setar, Kedah. Bidirectional sequencing indicates that 25% of our childhood deafness has mutation in their GJB2 gene. Sixty two percent of these children demonstrate V37I missense mutation. Interestingly, V37I mutation in the GJB2 gene have been reported as polymorphism in Western countries, however in our country it behaved as a potentially disease-causing missense mutation, causing childhood deafness as it was not found in the normal control.
The prevalence of ocular abnormalities was studied in 165 children from a Malaysian school for the deaf. Ninety-five children (57.6%) had one or more ocular abnormalities. Rubella retinopathy was the commonest form of ocular abnormality (35.2%). Refractive errors were found in 23 children (13.9%). Refractive errors in the rubella group were significantly more common than in the non-rubella group of deaf children (p < 0.001) (chi 2 test). Thirteen children had congenital anomalies causing significantly impaired vision. Ophthalmological examination of deaf children helps in the detection of cases with rubella eye signs and thus helps to identify the cause of deafness. Since deaf children are at greater risk of visual and ocular abnormalities, periodical ophthalmological examination should be carried out in these children.
One hundred and sixty-five children from the school for the deaf were screened to find out the aetiology of deafness. The screening included routine ophthalmological examination. Aetiology was unknown in 33 children (20%). Prenatal infection was found to be the cause of deafness in 61 cases (36.96%). Rubella eye signs were found in 59 children (35.76%), whereas the history of rubella infection during the first trimester of pregnancy was found in only 33 of these cases (55.93%). Perinatal complications were seen in 20 children (12.12%). Twenty children (12.12%) had meningitis during their early childhood period. Routine ophthalmological examination helped us to pick up cases with rubella eye signs. Ophthalmological examination should be included as part of any study done to find out the cause of deafness.