Spinocerebellar ataxia type 2 (SCA2) in an Egyptian family presenting with polyphagia and marked CAG expansion in infancy

Abstract

We describe an Egyptian family having SCA2 affecting three generations with marked molecular and clinical anticipation observed in the index case. Our proband was a male child starting as early as 2 years old with progressive extrapyramidal manifestations, slow eye movements and cognitive impairment. A history of nonspecific mild developmental delay was recorded. The patient lost all cognitive functions, had persistent dystonic posture, trophic changes, vasomotor instability, dysphagia and died at the age of 7 years. The age at presentation among other affected family members varied between 11 and 45 years old across three generations. The early common neurological symptoms were choreoathetotic movements, myoclonic jerk, gait difficulty, expressionless face and emotional liability. Later, overt ataxia, incoordination, dysarthria, mild dementia and slow eye saccades predominated. Brisk tendon reflexes were detected in three cases. Peripheral nerve affection was a late manifestation. Interestingly, polyphagia and obesity were striking manifestations in the middle stage of the disease; an observation that might support a previously suggested relation between the ataxin-2 gene and body weight. The proband showed an amplified allele with marked CAG expansion in the form of a smear sized 69-75 repeats resulted from maternal transmission. To our knowledge, our index case is the second report in the literature presenting with infantile onset SCA2 and intermediate repeat expansion. This family expands the phenotypic spectrum of early onset SCA2 and points out the importance of considering SCA2 gene analysis in children with progressive neurological impairment and abnormal movements with or without polyphagia.