What are the genetic changes related to pontocerebellar hypoplasia ?
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 genes associated with pontocerebellar hypoplasia appear to play essential roles in the development and survival of nerve cells (neurons). Many of these genes are known or suspected to be involved in processing RNA molecules, which are chemical cousins of DNA. Fully processed, mature RNA molecules are essential for the normal functioning of all cells, including neurons. Studies suggest that abnormal RNA processing likely underlies the abnormal brain development characteristic of pontocerebellar hypoplasia, although the exact mechanism is unknown. Researchers hypothesize that developing neurons in certain areas of the brain may be particularly sensitive to problems with RNA processing.  Some of the genes associated with pontocerebellar hypoplasia have functions unrelated to RNA processing. In most cases, it is unclear how mutations in these genes impair brain development.