Abstract
A family is reported in which a brother and sister both showed non-progressive cerebellar ataxia, aplasia of the pupillary zone of the iris, and mild mental subnormality. These clinical findings were similar to those in two previous case reports. Despite the birth of an affected son to the affected sister, this family is considered to confirm autosomal recessive inheritance of this syndrome. The paternity of the mother's husband is supported by blood groups and biochemical markers and it is presumed that the husband is a heterozygote, even though no consanguinity could be detected.