Hypomyelinating Leukodystrophy-8

**Semantic type:** Disease or Syndrome

**Definition:** An autosomal recessive condition caused by mutation(s) in the POLR3B gene, encoding DNA-directed RNA polymerase III subunit RPC2. It is characterized by early onset cerebellar ataxia and mild intellectual disability. Diffuse cerebral hypomyelination and cerebellar atrophy are apparent on MRI. Hypogonadotropic hypogonadism and hypodontia are also features of this condition.

**Synonyms:** - 4H Syndrome - HLD8 - Hypomyelination-Hypogonadotropic Hypogonadism-Hypodontia Syndrome