Prelingual non-syndromic (isolated) deafness is the most frequent hereditary sensory defect. In >80% of the cases, the mode of transmission is autosomal recessive. To date, 14 loci have been identified for the recessive forms (DFNB loci). For two of them, DFNB1 and DFNB2, the genes responsible have been characterized; they encode connexin 26 and myosin VIIA, respectively. In order to evaluate the extent to which the connexin 26 gene (Cx26) contributes to prelingual deafness, we searched for mutations in this gene in 65 affected Caucasian families originating from various countries, mainly tunisia, France, New Zealand and the UK. Six of these families are consanguineous, and deafness was shown to be linked to the DFNB1 locus, 10 are small non consanguineous families in which the segregation of the trait has been found to be compatible with the involvement of DFNB1, and in the remaining 49 families no linkage analysis has been performed. A total of 62 mutant alleles in 39 families were identified. Therefore, mutations in Cx26 represent a major cause of recessively inherited prelingual deafness since according to the present results they would underlie approximately half of the cases. In addition, one specific mutation, 30delG, accounts for the majority (approximately 70%) of the Cx26 mutant alleles. It is therefore one of the most frequent disease mutations so far identified. Several lines of evidence indicate that the high prevalence of the 30delG mutation arises from a mutation hot spot rather than from a founder effect. Genetic counseling for prelingual deafness has been so far considerably impaired by the difficulty in distinguishing genetic and non genetic deafness in families presenting with a single deaf child. Based on the results presented here, the development of a simple molecular test could be designed which should be of considerable help.

Failure of supraglottoplasty was only observed in cases of laryngomalacia with ACAs. The complication rate was similar whether or not ACAs were present.

Between 1987 and 1993, 115 children were operated on for severe forms of laryngomalacia in two pediatric ear, nose, and throat (ENT) departments. The criteria used to determine the severity of the illness were selected following short hospitalization periods during which the children received both pediatric and ENT checkups. Based on clinical manifestations and/or the results of pH monitoring gastroesophageal reflux was found to be present in 68% of the children in the study. Detailed analysis and endoscopy were used to differentiate the symptoms that were related to laryngomalacia from those that were caused by other conditions, including mixed-breathing, swallowing, and sucking difficulties. Endoscopic resection of the aryepiglottic folds, with or without the use of a carbon dioxide laser, resulted in rapid improvement of both ventilation and swallowing. The success rate of this simple and effective procedure, which has no inherent morbidity, was 98% in an average follow-up period of 30 months. Only seven children required an additional similar procedure. The procedure failed in only two children, who needed to be tracheotomized. Given these excellent results, endoscopic resection can be considered an effective technique for the management of severe laryngomalacia.

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