Prevalence and nature of connexin 26 mutations in children with non-syndromic deafness.

OBJECTIVE: To determine (1) the prevalence and nature of connexin 26 mutations in a cohort of Australian children with non-syndromic hearing loss, and (2) the carrier frequency of the common connexin 26 mutation (35delG) in the general population. DESIGN: A cohort, case-finding study. Mutation analysis was performed on DNA extracted from white blood cells, buccal cells, or Guthrie blood spots. SETTING: A hearing loss investigation clinic and a deafness centre in two Australian capital cities, 1 January 1998 to 31 October 2000. PARTICIPANTS: (1) 243 children (age range, 4 weeks to 16 years; median, 4 years), attending hearing loss clinics in Sydney and Melbourne; (2) 1000 blood samples obtained from anonymous Guthrie card blood spots collected in 1984 [corrected] by the Victorian Clinical Genetics Service as part of the newborn screening program. MAIN OUTCOME MEASURES: (1) The prevalence and types of connexin 26 mutations in a cohort of children with prelingual deafness; (2) the carrier frequency of the common connexin 26 mutation, 35delG, in the general population. RESULTS: Connexin 26 mutations were identified and characterised in 52 (21%) of the 243 children; 14 different mutations, including four previously unreported mutations (135S, C53R, T123N and R127C), were identified. The common 35delG mutation was found in 56 of the 104 alleles (ie, 86 of the connexin 26 alleles in which a mutation was positively identified). The mutations V371 and M34T were also relatively common. The carrier frequency of connexin 26 mutations and of the common 35delG connexin 26 mutation in the Victorian population was estimated to be 1 in 54 and 1 in 100, respectively. CONCLUSIONS: Mutations in the connexin 26 gene (especially the 35delG mutation) are a common cause of prelingual hearing loss in Australia.

Early intervention: the professional views and referral practices of paediatricians in Victoria.

Early intervention services for young children with developmental disabilities have developed considerably in the past decade, yet little information is available about the referral practices and views of Australian paediatricians. During 1991, 100 paediatricians in Victoria completed a postal questionnaire designed to gain information regarding their attitudes to early intervention and referral practices. The results indicated that paediatricians had a positive view of early intervention, and perceived the standard and quality of the services in their region as comprehensive (16%) or adequate (54%). They were likely to make prompt referrals in the presence of an established disability (75%), but with suspected developmental delay, many (45%) were likely to wait until the delay was confirmed. Referrals were more often made for intervention for the child rather than for family support. However, paediatricians felt that early intervention had a beneficial effect on family functioning (81%). In general, the results indicate that there seem to be few barriers between paediatricians and the early intervention field.