Objective: To provide a description of a case of a young patient with atypical Parkinsonism with a mutation in SCA5.

Background: While several scpinocerebellar ataxias are known to present with levodopa responsive Parkinsonism, little is known about SCA5.

Method: Clinical description and laboratory testing.

Results: For the last 5 years, we have been following a 40-year-old patient with Parkinsonism with onset at 33 years. This began with right sided bradykinesia.
Family history revealed his paternal grandfather had been diagnosed with PD.
Currently he complains of difficulty using his right hand, dragging his right leg, and sometimes slight unsteadiness; also right arm tremor, and muscle pain during off periods, frequent urination and occasional depression.
He is on levodopa (750 mg daily) a 50% – 70% reduction in symptoms. Mild dyskinesaias are present.
On examination (off time) a severe asymmetry of motor symptoms was noteworthy with severe bradykinesia and muscle rigidity on the right and mild on the left. There was moderate rest tremor on right arm and slight kinetic tremor of both arms. Cognitive functions were completely normal. He had frequent urination and there were no other autonomic abnormalities. The rest of the neurologic exam was normal.
Laboratory blood tests were normal (including ceruloplasmin, urine copper and liver tests). MRI of brain was normal.
Whole exome sequencing at the UCL Institute of Neurology Queen Square showed: SPTBN2 (ENST00000309996), c.548T>G, p.Leu183Arg c.548T>G in SPTBN2 has an ultra-rare MAF in gnomAD and is predicted to be damaging and deleterious by SIFT and Polyphen. No abnormalities were found in genes associated with Parkinson disease.

Conclusion: This patient presents with rapidly progressive Parkinsonism, and a mutation in the gene for SCA5. At this time, there is no evidence of cerebellar abnormalities. This type of presentation has been reported previously in both SCA2 and 3 with cerebellar abnormalities presenting much later in the course of the disease.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/sca5-a-new-cause-of-parkinsonism/