Determination of genetic frequency and genotypic-phenotypic characteristics of cases with Spinocerebellar Ataxia Type 1,2,3,6 and Friedreich Ataxia

Introduction/Aim: Cerebellar Ataxia can be defined as the loss of balance and coordination due to various causes emerging in the cerebellum or related pathways. Ataxias can be classified as congenital, hereditary, sporadic and non-hereditary (infections, toxins, drugs and systemic reasons etc). In this study, overlapping features of clinical and phenotypic findings of patients diagnosed as spinocerebellar ataxia and SCA 1,2,3,6 and FA of known phenotype were investigated.Materials and Methods: In this study, total of 144 cases, 15 of whom were siblings and 129 of whom were diagnosed as spinocerebellar ataxia according to their clinical, laboratory and electrophysiological evaluations, were included. Genetic analyses were performed on all patients who were referred to Cukurova University Neurology Clinic.Physical examinations with detailed neurological examination along with dysmorphic features and degenerative stigma were recorded. Phenotypic features were documented utilizing the data obtained. Pedigree analysis were performed. Electroneurography and stimulated potential measurements, cerebral-spinal MRG and electrocardiographic investigations were completed. Blood samples were taken and phenotypic and genotypic characteristics of FA and SCA subtypes 1,2,3, and 6 were investigated throughly. SPSS 17.0 software pack was used for statistical analysis.Results: Almost 50% of patients were defined as FA. Moreover, two SCA 1 and one SCA 6 cases were determined. Increase in GAA trinucleotide expansion was found in a sibling of a subject diagnosed as SCA 6. Furthermore, SCA 8 expansion along with GAA trinucleotide expansion was found in a patient with Friedreich Ataxia .Conclusion: If we come across to a spinocerebellar ataxia patient based on hereditary background, first of all the patient should be evaluated in terms of FA. In the meantime, different variants of the SCA should also be considered. Upon detailed investigation of phenotypic characteristics, it was found that two main features help to distinguish SCA 1 and SCA 6 from other groups which are saccadic eye movements and extrapyramidal findings, respectively.Key words: Hereditary, ataxia, autosomal dominat autosomal recessive, triplet repeats, Friedreich, Spinocerebellar