Pontocerebellar hypoplasia (PCH) is a heterogeneous group of rare neurodegenerative disorders caused by genetic mutations and characterised by progressive atrophy of various parts of the brain such as the cerebellum or brainstem (particularly the pons).

In each parent the other copy performs its proper function and they display no signs of PCH.

A child inheriting two damaged copies of the gene will be affected by PCH.

[2] Mutations in the genes that cause PCH produce faults in the production of chemicals, usually enzymes, that are required for the development of nerve cells (neurons) and for properly processing RNA, which is needed for any cell to function normally.

The exact mechanism by which PCH affects the development of the cerebellum and pons is not well understood.