Objective: Spinocerebellar ataxia type 15 (SCA15) is a rare and understudied autosomal dominant cerebellar ataxia. The clinical and genetic characteristics of SCA15 are not well defined, hence the diagnosis is always challenging. We present a unique case of SCA15.

Background: A 59 year old woman presented with the history of head tremors since 30 years. Then she developed bilateral hand tremors around 10 years later. Subsequently, she developed cervical dystonia, 5 years later. Then she started having imbalance while walking which gradually progressed over last 10 years. Over last 4 years, she started having recurrent falls, and required support to walk. She also developed postural abnormalities over last 2 years. There was no change in speech. Autonomic dysfunction was there in form of increased bladder voiding frequency, urgency, urge incontinence and severe constipation. There was no family history, no history of drug or toxin exposure.

Method: On clinical examination, she had hypometric saccades, vertical more than horizontal and broken pursuits. She had right torticolis, retrocolis, dystonic ‘No-No’ head tremors. Bilateral postural action tremors were present. Finger nose ataxia was present in right more than left hand. There was no rigidity, no bradykinesia and no motor weakness. Ankle jerks were diminished and joint position sense was impaired. Her gait was ataxic and she required support to walk. Her MRI brain showed cerbellar atrophy.

Results: Genetic study was done; SCA panel was negative but clinical exome study showed heterozygous missense variant in exon 13 of the ITPR1 gene. Hence in view of the clinical, neuroimaging and genetic analysis diagnosis of SCA15 was considered.

Conclusion: This case highlights the atypical presentation and clinical course of SCA15. Though a rare cause of hereditary ataxia, but it should always be considered in a slowly progressive cerebellar ataxia tremor syndrome.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/expanding-the-clinical-and-genetic-spectrum-of-sca15-a-rare-case-report/