AsianScientist (Apr. 28, 2016) – Researchers from Japan have discovered a gene that can cause intellectual disabilities with seizures and low muscle tone, PIGG. The study, published in the American Journal of Human Genetics, reveals PIGG’s significant role to the development of the cerebral nervous system.
Associate Professor Yoshiko Murakami from the Research Institute for Microbial Diseases, Osaka University and colleagues based their discovery on an analysis of five patients from three families who showed severe delays in psycho-motoric development and epilepsy.
In most cases, the cause of intellectual disorders with seizures and hypotonia are unknown. Glycosylphosphatidylinositol (GPI) is a glycolipid that is attached to proteins, allowing them to be inserted in the cell membrane and displayed on the surface of the cell. In 2006, Murakami’s research group reported on the first inherited GPI deficiency, a condition characterized by abnormal blood clotting and seizures.
At least 27 genes are known to be involved in the biosynthesis and modification of GPI anchors. Out of these 27 genes, mutations in 13 genes have been linked to inherited GPI deficiencies. In these cases, symptoms arise due to the decrease of various GPI-anchored proteins that are transported to the surface of nerve cells.
In the present study, the researchers have discovered that PIGG is the 14th gene associated with inherited GPI deficiencies. Unlike the other 13 genes, however, individuals with mutations in PIGG still showed normal transport of GPI-anchored proteins to the cell surface, obscuring the importance of PIGG‘s function.
The current research showed that mutations of PIGG are the cause of severe cranial nerve problems and that PIGG plays an extremely important role in the development of the cerebral nervous system.
With these results, the researchers hope to raise awareness of inherited GPI deficiencies and give patients the opportunity to screen for the condition.
The article can be found at: Makrythanasis et al. (2016) Pathogenic Variants in PIGG Cause Intellectual Disability with Seizures and Hypotonia.
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Source: Osaka University.
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