Features include very common findings: Dysarthria, Global developmental delay, Intellectual disability, and Demyelinating peripheral neuropathy; and common findings: Delayed speech and language development, Impaired distal proprioception, Delayed ability to walk, and Babinski sign and others. 21 total HPO annotations.

POLR3B function has not been fully characterized.

Charcot-Marie-Tooth disease, demyelinating, IIA 1I is associated with mutations in the POLR3B gene on chromosome 12.

Genetic testing for POLR3B is available. Testing is considered confirmatory for diagnosis.

Phenotype severity distribution: 4 very common features, 11 common features.