Screening for gap junction protein beta-2 gene mutations in Malays with autosomal recessive, non-syndromic hearing loss, using denaturing high performance liquid chromatography.

OBJECTIVE: To determine the frequency and type of gap junction protein beta-2 gene mutations in Malay patients with autosomal recessive, non-syndromic hearing loss. METHODS: A total of 33 Malay patients with autosomal recessive, non-syndromic hearing loss were screened for mutations in the Cx26 coding region. Deoxyribonucleic acid was extracted from buccal swab samples and subjected to polymerase chain reaction. Slow-reannealing was performed, followed by screening using denaturing high performance liquid chromatography. RESULTS: Eight of the samples (24.2 per cent) showed heterozygous peaks, and further sequencing of these samples revealed four patients (50.0 per cent) with the W24X mutation, two (25.0 per cent) with the V37I mutation and another two (25.0 per cent) with the G4D mutation. CONCLUSIONS: Analysis of buccal swab samples by denaturing high performance liquid chromatography is noninvasive and suitable for rapid and reliable screening of gap junction protein beta-2 gene mutations in patients with autosomal recessive, non-syndromic hearing loss. Malay patients with autosomal recessive, non-syndromic hearing loss have different kinds of gap junction protein beta-2 gene mutations which are rarely found in other populations.

Hearing screening of infants in Neonatal Unit, Hospital Universiti Sains Malaysia using transient evoked otoacoustic emissions.

The objective of this prospective study was to report on the prevalence of hearing impairment in the neonatal unit population. From 15 February 2000 to 15 March 2000 and from 15 February 2001 to 15 May 2001, 401 neonates were screened using transient evoked otoacoustic emissions (TEOAE) followed by second-stage screening of those infants who failed the initial test. Eight (2 per cent) infants failed one ear and 23 (5.74 per cent) infants failed both ears, adding up to 7.74 per cent planned for second-stage screening. Five out of 22 infants who came for the follow up failed the screening, resulting in a prevalence of hearing impairment of 1 per cent (95 per cent confidence interval [95% CI]: 0.0-2.0). Craniofacial malformations, very low birth weight, ototoxic medication, stigmata/syndromes associated with hearing loss and hyperbilirubinaemia at the level of exchange tranfusion were identified to be independent significant risk factors for hearing impairment, while poor Apgar scores and mechanical ventilation of more than five days were not. In conclusion, hearing screening in high-risk neonates revealed a total of 1 per cent with hearing loss. The changes in the risk profile indicate improved perinatal handling in a neonatal population at risk for hearing disorders.