ABSTRACT
The spinocerebellar ataxias [SCA] comprise a heterogeneous group of severe late-onset neurodegenerative diseases promoted by the expansion of a tandem-arrayed DNA sequence that modify the primary structure of the protein. SCA is a genetic disease with multiple types, each of which could be considered a disease in its own right, and cannot be differentiated rapidly from each other on a clinical basis. As with other forms of ataxia, SCA results in unsteady and clumsy motion of the body due to a failure of the fine coordination of muscle movements, along with other symptoms. A variety of deadly diseases are attributable to a large number of accumulated mutations in mitochondria. Percentage levels of mutant mtDNA in blood have been reported in some patients with neurological disease, usually in association with much higher levels of mutant mtDNA in skeletal muscle. Mitochondrial DNA [mtDNA] defects may present with cerebellar ataxia. MtDNA rearrangements are usually sporadic and may cause ataxia. MtDNA point mutations may be responsible for the ataxia seen in some SCA mutation negative families. Point mutations such as those affecting tRNALeuUUR are particularly common in human mitochondrial diseases. Genomic DNA of 20 patients with clinical symptoms of SCAs was purified from peripheral blood and screened for deletions in mitochondrial DNA [mtDNA]. Genetic analysis Segments of the genes SCA1, SCA2, MJD [SCA3], CACNA1A [SCA6], and SCA7 harboring the CAG-repeat region were amplified in five separate reactions for molecular diagnosis for each patient. Also the sequencing of tRNA[Leu[UUR]], tRNA[Lys], ATPase 6, ATPase8,COII, COIII, ND1, 16srRNA of mtDNA was performed in patients with genetically affected SCA to find out if they harbor any mutation in these regions or not