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.
Pediatric movement disorders are still a diagnostic challenge, as many patients remain without a (genetic) diagnosis. Magnetic resonance imaging (MRI) pattern recognition can lead to the diagnosis. MEGDEL syndrome (3-MethylGlutaconic aciduria, Deafness, Encephalopathy, Leigh-like syndrome MIM #614739) is a clinically and biochemically highly distinctive dystonia deafness syndrome accompanied by 3-methylglutaconic aciduria, severe developmental delay, and progressive spasticity. Mutations are found in SERAC1, encoding a phosphatidylglycerol remodeling enzyme essential for both mitochondrial function and intracellular cholesterol trafficking. Based on the homogenous phenotype, we hypothesized an accordingly characteristic MRI pattern. A total of 43 complete MRI studies of 30 patients were systematically reevaluated. All patients presented a distinctive brain MRI pattern with five characteristic disease stages affecting the basal ganglia, especially the putamen. In stage 1, T2 signal changes of the pallidum are present. In stage 2, swelling of the putamen and caudate nucleus is seen. The dorsal putamen contains an "eye" that shows no signal alteration and (thus) seems to be spared during this stage of the disease. It later increases, reflecting progressive putaminal involvement. This "eye" was found in all patients with MEGDEL syndrome during a specific age range, and has not been reported in other disorders, making it pathognomonic for MEDGEL and allowing diagnosis based on MRI findings.
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.