Objective: To conduct a clinical and genetic analysis of SCA 1 in Indian population.

Background: Spinocerebellar ataxia type1 (SCA1) is a neurodegenerative disease caused by expansion of a CAG trinucleotide repeat in ataxin-1(ATXN1) gene. The subjects present with a varied clinical spectrum and thus this study aimed at exploring any correlation between trineucleotide repeat and symptoms.

Methods: This study was conducted for clinico-genetic analysis of 71 unrelated SCA1 patients. The diagnosis was based on suggestive neurological examination, radiology, nerve conduction studies, and CAG repeats screening the genomic DNA of patients.

Results: A total of 71 SCA1 patients comprised male:female 52:19 with following demographics, mean(SD) of age 37.05(11.01)years, age of onset (AO), 32.53(9.22), disease duration was 4.69(3.45) with CAG repeats expansion 50.70(6.01) in the range (38-65). An inverse correlation was observed between CAG and AO with correlation coefficients upon linear model, r-0.72; y=-1.165X+61.46, p-value<10-4). Affected patients showed features of gait ataxia (87.33%), Tremor(35.20%), Dysarthria(81.7%), Hyperreflexia(47.9%), Babinski sign(32.4), Nystagmus(21.1%), Slow saccades(36.6%) and NCS abnormality. Hyperreflexia associated with later AO and age (p-value, 0.05), while nerve-conduction-abnormalities were observed with early onset (marginally significant-p-value, 0.10). CAG length do not explain occurrence of various neurological impairment. We also observed different SCA1 clinical subtypes: Type-I(pure cerebellar), Type-II (cerebellar-plus-pyramidal features), Type-III (Cerebellar-plus-brain stem involvement) and Type-IV(Mixed: cerebellar/pyramidal/extrapyramidal/brain stem involvement).

Conclusions: This is the largest clinico-genetic case series from Indian population for SCA1. Our study showed that SCA1 is a heterogenous disorder with major features of cerebellar ataxia and hyperreflexia.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/clinico-genetic-correlation-in-indian-spinocerebellar-ataxia-type-1-sca1-patients/