BROADENED FRIEDREICHS ATAXIA PHENOTYPE AFTER GENE CLONING - MINIMAL GAA EXPANSION CAUSES LATE-ONSET SPASTIC ATAXIA

We describe three siblings from an Italian family affected by an autos omal recessive spinocerebellar degeneration. Gait ataxia, presenting b etween 38 and 45 years, was the first symptom in all three patients. D ysarthria, dysmetria, brisk tendon reflexes, extensor plantar response , and scoliosis were constant features. Disease progression was slow. Electrophysiologic studies demonstrated a slight reduction in sural ne rve sensory action potential in only one patient. Analysis of GAA expa nsion within the X25 gene showed that patients were homozygous for the expansion, with the shorter expanded allele ranging from 120 to 156 t riplets. The size of the GAA expansion may be smaller than we previous ly described. Such minimal expansions may result in atypical forms of Friedreich's ataxia.