Huntington disease-like 3 is a rare Huntington disease-like syndrome characterized by childhood-onset progressive neurologic deterioration with pyramidal and extrapyramidal abnormalities, chorea, dystonia, ataxia, gait instability, spasticity, seizures, mutism, and (on brain MRI) progressive frontal cortical atrophy and bilateral caudate atrophy. The disease is Monarch Disease Ontology identifier MONDO_0011487 (Huntington disease-like 3). Also known as: HDL3, Huntington disease-like type 3.