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Genetic and Rare Diseases Information Center (GARD)

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Pontocerebellar hypoplasia

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Your Question

How common or rare is this condition? Can it be linked to prematurity as a cause?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

How many individuals have pontocerebellar hypoplasia?

The exact prevalence of pontocerebellar hypoplasia is unknown, although most forms of the disorder appear to be very rare.[1][2] More than 100 cases have been reported in the medical literature.[3]
Last updated: 12/18/2012

What causes pontocerebellar hypoplasia?

The different forms of pontocerebellar hypoplasia (PCH) are generally caused by mutations in several different genes. These genes appear to play important roles in the development and survival of nerve cells. However, it is unclear how mutations in these genes disrupt the normal development of the cerebellum and pons.[1] Research thus far has found that:[1][4]
  • PCH1A can be caused by mutations in the VRK1 gene
  • PCH1B is caused my mutations in the EXOSC3 gene
  • PCH2 is caused by mutations in the TSEN54, TSEN2, TSEN34, and SEPSECS genes
  • PCH4 is caused by mutations in the TSEN54 gene
  • PCH6 is caused by mutations in the RARS2 gene
  • PCH8 is caused by mutations in the CHMP1A gene

Specific genes that cause PCH3, PCH5 and PCH7 have not yet been identified.[4]

Although experts agree that PCH has a genetic cause, other causes (such as infectious or toxic) have been reported or suspected in some cases.[5]

Last updated: 12/19/2012

Is there an association between pontocerebellar hypoplasia (PCH) and premature birth?

The development of the cerebellar hemispheres and their connections with the pons occurs during the second month of gestation, when PCH is likely to originate.[5] Therefore, it is unlikely that premature birth alone could cause this condition.

During a thorough search of the available literature, we came across one report describing early fatal PCH in premature twin sisters born at 30 weeks gestation. The sisters reportedly also had hypertonia, jitteriness, hyperekplexia (exaggerated startle reaction), and progressive microcephaly and died at 7 weeks of age from respiratory failure. The authors stated that the severe involvement at 30 weeks gestation suggest an early fetal onset.[5]
Last updated: 12/19/2012