Clinical features of four unrelated Japanese patients with autosomal recessive spinocerebellar ataxia type 32.
Hiromi Fukuda, Hiroshi Doi, Shunsuke Ogata et al.
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Case in brief
Four unrelated Japanese patients with autosomal recessive spinocerebellar ataxia type 32 (SCAR32) were identified among 411 ataxia cases negative for repeat expansion disorders. Onset was between 9 and 30 years, and the phenotype was predominantly pure cerebellar ataxia; one patient had autoimmune comorbidities. MRI showed cerebellar atrophy and dentate-nucleus T2 hyperintensity in all four, with cerebellar cortical T2 hyperintensity in three. Genetic testing found biallelic PRDX3 nonsense variants in each patient. The report describes SCAR32 as an early-onset cerebellar ataxia diagnosis in this cohort.
What made this case unusual
Cerebellar cortical T2 hyperintensity was present in three patients, alongside dentate-nucleus T2 hyperintensity in all four; the authors suggest the cortical finding may be representative of SCAR32.
Diagnostic / clinical pearl
In early-onset autosomal recessive cerebellar ataxia, consider PRDX3-related SCAR32, particularly when MRI shows dentate-nucleus and cerebellar cortical T2 hyperintensity.
Why it matters
The authors report a 0.97% prevalence of SCAR32 in their undiagnosed ataxia cohort and note the relatively high p.Arg207* allele frequency in East Asians, supporting its relevance to ataxia evaluation in Japan.