Wolfram syndrome in a family with variable expression.

Wolfram syndrome is a rare neurodegenerative disorder with autosomal recessive inheritance. The main characteristic features of this disorder are diabetes mellitus and optic atrophy. However, diabetes insipidus, sensorineural deafness, renal tract and neurologic abnormalities are seen in majority of patients. In this study, we describe a family in which two members had the main features of the syndrome while a third sibling had only sensorineural deafness. DNA analysis revealed that the fully affected siblings were homozygote for a pointmutation on chromosome 4p whereas the third sibling with deafness was a heterozygote carrier for the same mutation. The characteristics of disease and phenotypic variations that possibly related to heterozygote carrier state were discussed.