Genetic posterior fossa malformation Non-syndromic pontocerebellar hypoplasia Pontoneocerebllar hypoplasia Pontoneocerebellar atrophy OMIM:618266 OMIM:617695 Nonsyndromic pontocerebellar hypoplasias (PCH) are a rare heterogeneous group of diseases characterized by hypoplasia and atrophy and/or early neurodegeneration of the cerebellum and pons. Eight subtypes named type 1-8 have been described (see these terms), generally inherited in an autosomal recessive pattern. orphanet PCH ICD10:Q04.3