Pontocerebellar hypoplasia is a group of related conditions that affect the development of the brain. The term "pontocerebellar" refers to the pons and the cerebellum, which are the brain structures that are most severely affected in many forms of this disorder. The pons is located at the base of the brain in an area called the brainstem, where it transmits signals between the cerebellum and the rest of the brain. The cerebellum, which is located at the back of the brain, normally coordinates movement. The term "hypoplasia" refers to the underdevelopment of these brain regions.

Pontocerebellar hypoplasia can result from mutations in several genes. About half of all cases of PCH1 are caused by mutations in the EXOSC3 gene. PCH1 can also result from mutations in several other genes, including TSEN54, RARS2, and VRK1. PCH2 is caused by mutations in the TSEN54, TSEN2, TSEN34, or SEPSECS gene. In addition to causing PCH1 and PCH2, mutations in the TSEN54 gene can cause PCH4 and PCH5. Mutations in the RARS2 gene, in addition to causing PCH1, can result in PCH6. The remaining types of pontocerebellar hypoplasia are caused by mutations in other genes. In some cases, the genetic cause of pontocerebellar hypoplasia is unknown.

The prevalence of pontocerebellar hypoplasia is unknown, although most forms of the disorder appear to be very rare.

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Published Date: November 01, 2014
Published By: National Institutes of Health