SPINOCEREBELLAR ATAXIA TYPE-2 (SCA-2) IN AN INFANT WITH EXTREME CAG REPEAT EXPANSION

Autosomal dominant cerebellar ataxias are a heterogeneous group of neu rodegenerative disorders that generally present in adulthood. Spinocer ebellar ataxia type 2 typically presents with progressive cerebellar s ymptoms, slow ocular saccades, and peripheral neuropathy. The onset of symptoms is usually between 20 and 40 years. We describe an infant wh o presented with neonatal hypotonia, developmental delay, and dysphagi a. Ocular findings of retinitis pigmentosa were noted at 10 months. He r father had mild spinocerebellar ataxia first noted at age 22 years. Molecular studies of the SCA2 gene showed a CAG expansion of 43 repeat s in the father and an extreme CAG; repeat expansion of more than 200 in the baby. Our report expands the known phenotype and genotype of SC A2. Testing for dominant ataxias should be included in the evaluation of infants with nonspecific progressive neurologic symptoms and retini tis pigmentosa, especially in cases with a positive family history for spinocerebellar ataxia. Am. J. Med, Gen. 79:383-387, 1998. (C) 1998 W iley-Liss, Inc.