Makrythanasis, P, Kato, M, Zaki, MS et al. (18 more authors) (2016) Pathogenic Variants in PIGG Cause Intellectual Disability with Seizures and Hypotonia. American Journal of Human Genetics, 98 (4). pp. 615-626. ISSN 0002-9297
Abstract
Glycosylphosphatidylinositol (GPI) is a glycolipid that anchors >150 various proteins to the cell surface. At least 27 genes are involved in biosynthesis and transport of GPI-anchored proteins (GPI-APs). To date, mutations in 13 of these genes are known to cause inherited GPI deficiencies (IGDs), and all are inherited as recessive traits. IGDs mainly manifest as intellectual disability, epilepsy, coarse facial features, and multiple organ anomalies. These symptoms are caused by the decreased surface expression of GPI-APs or by structural abnormalities of GPI. Here, we present five affected individuals (from two consanguineous families from Egypt and Pakistan and one non-consanguineous family from Japan) who show intellectual disability, hypotonia, and early-onset seizures. We identified pathogenic variants in PIGG, a gene in the GPI pathway. In the consanguineous families, homozygous variants c.928C>T (p.Gln310(∗)) and c.2261+1G>C were found, whereas the Japanese individual was compound heterozygous for c.2005C>T (p.Arg669Cys) and a 2.4 Mb deletion involving PIGG. PIGG is the enzyme that modifies the second mannose with ethanolamine phosphate, which is removed soon after GPI is attached to the protein. Physiological significance of this transient modification has been unclear. Using B lymphoblasts from affected individuals of the Egyptian and Japanese families, we revealed that PIGG activity was almost completely abolished; however, the GPI-APs had normal surface levels and normal structure, indicating that the pathogenesis of PIGG deficiency is not yet fully understood. The discovery of pathogenic variants in PIGG expands the spectrum of IGDs and further enhances our understanding of this etiopathogenic class of intellectual disability.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Medicine and Health (Leeds) > School of Medicine (Leeds) > Inst of Biomed & Clin Sciences (LIBACS) (Leeds) > Genetics (LIBACS) (Leeds) The University of Leeds > Faculty of Medicine and Health (Leeds) > Institute of Molecular Medicine (LIMM) (Leeds) > Section of Opthalmology and Neurosciences (Leeds) |
Funding Information: | Funder Grant number Jules Thorn Charitable Trust NOT GIVEN Great Ormond St. Hosp. Childrens Charity V1217 |
Depositing User: | Symplectic Publications |
Date Deposited: | 03 Oct 2016 15:35 |
Last Modified: | 03 Nov 2016 01:02 |
Published Version: | http://dx.doi.org/10.1016/j.ajhg.2016.02.007 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.ajhg.2016.02.007 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:98104 |