July 29, 2026

@michaelokun

"Huntington disease-like." It may be one of the least favorite names in movement disorders, and today's Aspen discussion with Joe Jankovic highlighted why. Calling a condition "Huntington disease-like" defines it by what it is not, rather than what it is. These disorders have their own biology, genetics, and clinical features. HDL1 is linked to PRNP mutations and often includes seizures and prominent psychiatric symptoms. HDL2, caused by JPH3 expansions, occurs almost exclusively in individuals of African ancestry and typically lacks seizures. HDL3, an exceedingly rare childhood-onset disorder reported in a single Saudi Arabian family, presents with developmental delay, dystonia, spasticity, ataxia, and dysarthria. HDL4 is now recognized as spinocerebellar ataxia type 17 (SCA17), caused by TBP repeat expansions, and can present with a remarkably broad spectrum of movement, cognitive, and psychiatric symptoms. My takeaway was simple: as our understanding of genetics advances, our terminology should evolve as well. Patients deserve diagnoses that reflect the underlying disease biology, not labels that simply describe what the disorder happens to resemble.