In SCA patients with crisis the mean serum Placenta growth factor level was 19.97±1.28 pg/ml; in SCA patients out of crisis the mean serum Placenta growth factor level was 13.12 ± 1.82 pg/ml and in controls the mean value was 9.89 ± 1.20 pg/ml. The gene discussed is PGF; the disease is autosomal dominant cerebellar ataxia.