Recurrence risks for near relatives of children with sensori-neural deafness

In a sample of children with sensori-neural deafness and no evidence of a syndrome, ototoxic exposure, or autosomal dominant or X-linked family history, seen in the Division of Medical Genetics of The Montreal Children's Hospital, the probability of a sibling being similarly affected was about 1 in 6, both in French-Canadian families and the remainder of the sample. The frequency of deafness of early onset was measured in the uncles and aunts of probands, and these figures were used to derive approximate recurrence risks for the offspring of probands (about 1 in 130, ignoring the possibility of autosomal dominant mutation) and for the offspring of the probands' unaffected sibs (about 1 in 250). A rough estimate of the number of autosomal recessive loci contributing to sensori-neural deafness is derived as 13.     

Effects of purine amino groups on the development of Drosophila

The effect of a variety of 6-substituted purines on development of Drosophila melanogaster, eggs and larva, were studied. Purine and 2,6-diaminopurine both were very toxic to egg development. Adenine and 2,6-diaminopurine were moderately and equally toxic to larva development. Substitution on the 6-position of the purine ring was very effective in regulating metamorphosis of Drosophila.