Early onset, non-progressive, mild cerebellar ataxia co-segregating with a familial balanced translocation t(8;20)(p22;q13).

H ereditary ataxia is a clinically and genetically heterogenous group of disorders. Most are progressive and associated with other neurological abnormalities. Early onset, non-progressive cerebellar ataxia (OMIM #117360) has been described as a dominantly inherited disorder associated with isolated vermal atrophy or generalised atrophy of the cerebellum. 5 This is a rare entity compared with autosomal recessive early onset cerebellar ataxia with retained tendon reflexes (OMIM #212895). Various disease genes have been identified using rare disease associated balanced chromosomal rearrangements (DBCRs), for example, translocations or inversions that truncate, delete, or otherwise inactivate genes. DBCRs may occur in at least 1% of patients with autosomal dominant disorders caused by haploinsufficiency, and in many girls affected by X linked recessive disorders. During a systematic search for apparently balanced chromosomal rearrangements associated with abnormal phenotypes, we identified a four generation family in which a variable neurological phenotype including an early onset, non-progressive, and mild cerebellar ataxia segregates together with a balanced reciprocal translocation.