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Pontocerebellar hypoplasia type 5

Synonym(s) Fetal-onset olivopontocerebellar hypoplasia
Prevalence <1 / 1 000 000
Inheritance Autosomal recessive
Age of onset Infancy
  • Q04.3
MeSH -
MedDRA -


Disease definition

Pontocerebellar hypoplasia type 5 (PCH5) is a very rare severe form of PCH (see this terme) with prenatal onset and characterized by fetal onset of clonus or seizures-like activity persisting in infancy and microencephaly leading to early postnatal death. There is significant overlap both in phenotype and in genotype between pontocerebellar hypoplasia types 4 and 5.


PCH5 is reported in 3 siblings to date.

Clinical description

PCH5, clinically resembling PCH4 (see this term), is characterized by fetal onset of clonus or seizure-like episodes, microcephaly, cerebellar hypoplasia persisting in infancy and microencephaly leading to early postnatal death.


PCH5 is caused by a compound heterozygosity for p.A307S plus splice site mutation in the gene. PCH5 transmission is autosomal recessive.

Diagnostic methods

Clinically similar to PCH4, PCH5 is demonstrated on autopsy. MRI demonstrates inferior olivary dysplasia, and pontocerebellar hypoplasia with the vermis much more degenerated than cerebellar hemispheres. Pathological findings show and increased degeneration with Purkinje and granule cells in the vermis.

Antenatal diagnosis

Antenatal diagnosis is possible by ultrasonic assessment of cerebellar width at 16-18 weeks gestation.

Expert reviewer(s)

  • Pr F. [Frank] BAAS

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Detailed information

Review article
Clinical genetics review
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