Abstract
The spinocerebellar degeneration (SCD), also namedspinocerebellar atrophy or spinocerebellar ataxia (SCA), are acomplex disease comprising of heterogeneous neurologicdisorders. The most common clinical features of SCA aredisturbances of motor coordination and balance, which implydestruction of anatomical structure, i.e., cerebellum, spinaltracts and brainstem nuclei. Additional degenerative changesmay also occur in the eye, cerebrum, basal ganglia, spinal cordand peripheral nerve, on the basis oclinicopathologicalfindings.In general, SCDs could be classified into two groups, the firstbeing those for which a known cause has been identified and thesecond being those for hereditary disorders. Rarely, cerebellardegeneration is found in patients with ovarian cancer, oat cellcarcinoma, breast cancer or lymphoma.Although classifications of SCADs (Spinocerebellar ataxiaautosomal dominant) based on clinical and neuropathologicfindings have been proposed, it is quite difficult to define thedifferent subtypes of this group of diseases due to theoverlapping phenotypes and the variability of the clinicalmanifestation. Expanded CAG repeat sequences have beenidentified in the coding region of genes mutated in SCADs. Inall disorders, CAG expansion codes for an elongatedpolyglutamine chain(Torttier Y. et. al., 19).Nowadays, seven different loci associated with SCA have beenidentified with linkage studies. SCA1maps to chromosome 6p,SCA2 maps to chromosome 12q22-24, SCA3 maps to chromosome14q24.3, SCA4 maps to 16p22.1, SCA5 maps to chromosome 11, SCA6maps to chromosome 19 and SCA7 maps to chromosome 3.We study a family of SCAD with four generations in clinicalmanifestation and genetic study of CAG repeat.