Adult-onset Niemann-Pick disease type C masquerading as spinocerebellar ataxia.

The study established the correct molecular diagnosis of biallelic, adult-onset NPC in a patient initially diagnosed with SCA. Additionally, the p.Pro471Leu variant was identified as likely pathogenic. Inaccurate molecular diagnosis will deprive NPC patients of treatment options. Investigation using WES is justified when a detected expansion size is in the borderline range for pathogenicity.