Spinocerebellar ataxia 2 presenting as Parkinsonism: two families report and literatures review

Abstract

Objective To summarize the clinical, imaging and genetic characteristics of spinocerebellar ataxia 2 (SCA2) families presenting as Parkinsonism. Methods and Results Two families with autosomal dominant SCA2 with Parkinson's syndrome diagnosed by genetic test in Peking University First Hospital from May 2019 to December 2020 were included. The probands in 2 families manifested as lead⁃pipe like rigidity and cerebellum ataxia. Electronystagmography (ENG) in proband of family 1 showed gaze nystagmus, understable saccade, decreased smooth tracking ability and disappeared optokinetic nystagmus, proband of family 2 showed slow saccade, decreased smooth tracking ability and decreased optokinetic nystagmus. Head MRI in both probands of 2 families showed slightly enlarged third ventricle, while the proband of family 2 showed atrophy in brain stem and cerebellar. Whole exome sequencing (WES) in 2 probands showed no gene mutations, Sanger sequencing showed dynamic mutation of ATXN2 gene and the copy number of cytosine⁃adenine⁃guanine (CAG) with 37 repeats. Two probands were finally diagnosed as SCA2, and two pedigrees were diagnosed as SCA2 pedigrees. Conclusions SCA2 can present as Parkinsonism, which is easily to be misdiagnosed as Parkinson's disease due to the effective treatment of levodopa. ENG is helpful in detecting subclinical cerebellar lesions. For Parkinsonism patients with family history, especially when cerebellar lesions are involved, ATXN2 gene testing is recommended.

Keywords

• spinocerebellar ataxias
• parkinsonian disorders
• genes
• mutation
• trinucleotide repeat expansion
• pedigree