title: [Hereditary cerebellar ataxias: from hammer to genetics].
abstract: The hereditary ataxias comprise a complex group of neurological disorders involving the cerebellum and its connections. Several classifications based on clinical and/or pathological data have been only partially successful. Recent progress in molecular genetics has identified the genic loci of hereditary ataxias and has allowed a more precise diagnosis of distinct genetic diseases. Trinucleotide repeat expansions has been recognized as a mechanism of disease in some autosomal dominant spinocerebellar ataxias (ADCA) (SCA1 to SCA7), including Machado-Joseph disease/SCA3, probably the most common form of ADCA in South Brazil, and Friedreich ataxia (GAA expansion-chromosome 9p). Familial alpha-tocopherol deficiency (chromosome 8q) may have a Friedreich ataxia phenotype and responds to the oral supplementation with vitamin E. Familial episodic ataxias with (EA1-chromosome 12p) and without (chromosome 19p-EA2) myokimia were identified, the first one caused by point mutations in the gene encoding the KCNA1 potassium voltage-gated channel. The gene responsible for ataxia-teleangiectasia (chromosome 11q) was found to encode a putative DNA binding protein kinase (ATM), related to the cell cycle control. One to 3% of the population are heterozygotic ATM gen carry and pose a higher risk of cancer when exposed to ionizing radiation. Molecular biology has provided us with useful tools to diagnosis and genetic counseling and, hopefully, will provide us with a better understanding of the pathogenesis and eventual treatment of the several forms of hereditary ataxias.
authors.affiliation: Departamento de Clínica Médica, Universidade Federal do Paraná (UFPR), Brasil.
authors.forename: W O
authors.initials: WO
authors.lastname: Arruda
authors.forename: H A
authors.initials: HA
authors.lastname: Teive
mesh_terms: D006801:Humans; D013132:Spinocerebellar Degenerations / Q000145:classification* / Q000175:diagnosis* / Q000235:genetics
vernacular_title: Ataxias cerebelares hereditárias. Do martelo ao gen.