Late-onset Niemann-Pick C disease in a patient with spastic ataxia and hyperkinetic involuntary movements: a case report.
Daniele Orsucci, Roberta Bovenzi, Martina Giuntini et al.
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Case in brief
A woman with late-onset Niemann-Pick disease type C1 presented from age 50 with progressive postural instability, falls, spastic ataxia, and prominent upper-limb hyperkinetic movements. Examination also showed dystonia, myoclonus, intention tremor, bradykinesia, rigidity, supranuclear gaze limitation, and mild cognitive impairment. Whole-exome sequencing found compound heterozygous pathogenic NPC1 variants, c.3019 C > G (p.Pro1007Ala) and c.2861 C > T (p.Ser954Leu), confirmed in trans by segregation analysis. Elevated N-palmitoyl-O-phosphocholineserine and lysosomal storage abnormalities on skin biopsy supported the diagnosis.
What made this case unusual
The late-onset presentation combined spastic ataxia with prominent hyperkinetic upper-limb movements and supranuclear gaze limitation.
Diagnostic / clinical pearl
In late-onset ataxia, prominent hyperkinetic movements and supranuclear gaze abnormalities should prompt consideration of NPC1; genetic findings can be supported by biochemical testing and skin biopsy.
Why it matters
The report emphasizes considering NPC1 because the authors describe it as a potentially treatable disorder.