Connexin26 deafness in several interconnected families

Mutations in the connexin26 gene are the basis of much autosomal recessive sensorineural deafness. There is a high frequency of mutant alleles, largel y accounted for by one common mutation, 35delG. We have studied a group of families, who had been brought together through marriages between Deaf pers ons, in which there are more than 30 Deafpeople in four generations. We sho w that many of the several cases of deafness are the result of 35delG homoz ygosity or 35delG/Q57X compound heterozygosity at the connexin26 locus. A c onsiderable range of audiographic phenotypes was observed. The combined eff ects of a high population frequency of mutant alleles, and of positive asso rtative marriage among the Deaf, led to an infrequently observed recessive pedigree pattern.