Objective: Describe the clinical findings of a Brazilian cohort of SCA2 patients, stratify them according the presence of sub-phenotypes: cognitive deterioration, sensory loss, amiotrophy, parkinsonism to test to the possible association of the CAG-containing genes ATXN1, ATXN2, ATXN3, CACNA1A, ATXN7, RAI1 and the 10398G mitochondrial polymorphism with these sub-phenotypes.

Background: Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant cerebellar ataxia caused by the abnormal expansion of a CAG repeat, characterized by a progressive cerebellar syndrome starting in adulthood, associated with saccadic slowness. SCA2 presents a large variability of clinical signs. Factors that could modify the SCA2 phenotype have been studied .

Methods: Subjects with molecular diagnosis of SCA2 selected from Neurogenetic Network in Brazil were evaluated by motor scales: SARA, NESSCA, SCAFI and CCFS; cognitive scales: Mini Mental Examination, MOCA ; depression scale : BDI. They are submitted to DNA extraction and PCR to expansion in ATXN1,3,7,CACNA1A, RAI 1 and mitocondrial polymorphism 10390G.

Results: 46 patients with SCA 2 were examined. WE found association between cognitive decline and mitochondrial polymorphism 10398G (p=0.01).

Conclusions: Based on our strategy of study the patients acording the presence of specific neurologic syndromes we found association between cognitive decline in SCA2 and mytochondrial polymorphism 10398G. The same polymorphism was already described associated to age of onset in SCA2 but these finding was not present in our study. It may suggest that exists a potencial mitochondrial disfunction in SCA2 a usual phenomenon in other poliglutaminopathies.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/neurologic-phenotipic-variability-in-spinocerebelar-ataxia-hype-2-sca2/