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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed August 2013

What is the official name of the PIGO gene?

The official name of this gene is “phosphatidylinositol glycan anchor biosynthesis class O.”

PIGO is the gene's official symbol. The PIGO gene is also known by other names, listed below.

What is the normal function of the PIGO gene?

The PIGO gene provides instructions for making one part of an enzyme called GPI ethanolamine phosphate transfer 3 (GPI-ET3). The other part of the GPI-ET3 enzyme is produced from a gene called PIGF. The GPI-ET3 enzyme is involved in a series of steps that produce a molecule called a glycosylphosphosphatidylinositol (GPI) anchor. Specifically, this enzyme adds a molecule of ethanolamine phosphate to the end of the forming GPI anchor. This step takes place in the endoplasmic reticulum, which is a structure involved in protein processing and transport within cells. The complete GPI anchor attaches (binds) to various proteins in the endoplasmic reticulum; this process requires the ethanolamine phosphate at the end of the anchor. After the anchor and protein are bound, the anchor attaches itself to the outer surface of the cell membrane, ensuring that the protein will be available when it is needed.

Does the PIGO gene share characteristics with other genes?

The PIGO gene belongs to a family of genes called PIG (phosphatidylinositol glycan anchor biosynthesis).

A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? ( in the Handbook.

How are changes in the PIGO gene related to health conditions?

Mabry syndrome - caused by mutations in the PIGO gene

At least three mutations in the PIGO gene have been found to cause Mabry syndrome, a condition characterized by intellectual disability, distinctive facial features, increased levels of an enzyme called alkaline phosphatase in the blood (hyperphosphatasia), and other signs and symptoms. These mutations change single protein building blocks (amino acids) in the GPI-ET3 enzyme. The altered protein is less able to add ethanolamine phosphate to the end of GPI anchors. The incomplete GPI anchor cannot attach to proteins; without the anchor, the proteins cannot bind to the cell membrane and are released from the cell.

An enzyme called alkaline phosphatase is normally attached to the cell membrane by a GPI anchor. However, when the anchor is impaired, alkaline phosphatase is released from the cell. This abnormal release of alkaline phosphatase is responsible for the hyperphosphatasia in Mabry syndrome. It is unclear how PIGO gene mutations lead to the other features of Mabry syndrome, but these signs and symptoms are likely due to a lack of proper GPI anchoring of proteins to cell membranes.

Where is the PIGO gene located?

Cytogenetic Location: 9p13.3

Molecular Location on chromosome 9: base pairs 35,088,688 to 35,096,601

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The PIGO gene is located on the short (p) arm of chromosome 9 at position 13.3.

The PIGO gene is located on the short (p) arm of chromosome 9 at position 13.3.

More precisely, the PIGO gene is located from base pair 35,088,688 to base pair 35,096,601 on chromosome 9.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about PIGO?

You and your healthcare professional may find the following resources about PIGO helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the PIGO gene or gene products?

  • FLJ00135
  • GPI ethanolamine phosphate transferase 3
  • phosphatidylinositol glycan anchor biosynthesis, class O
  • phosphatidylinositol-glycan biosynthesis class O protein
  • PIG-O

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding PIGO?

acids ; cell ; cell membrane ; class ; disability ; endoplasmic reticulum ; enzyme ; gene ; glycan ; molecule ; phosphatase ; phosphate ; protein ; syndrome ; transferase

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Hong Y, Maeda Y, Watanabe R, Inoue N, Ohishi K, Kinoshita T. Requirement of PIG-F and PIG-O for transferring phosphoethanolamine to the third mannose in glycosylphosphatidylinositol. J Biol Chem. 2000 Jul 7;275(27):20911-9. (
  • Krawitz PM, Murakami Y, Hecht J, Krüger U, Holder SE, Mortier GR, Delle Chiaie B, De Baere E, Thompson MD, Roscioli T, Kielbasa S, Kinoshita T, Mundlos S, Robinson PN, Horn D. Mutations in PIGO, a member of the GPI-anchor-synthesis pathway, cause hyperphosphatasia with mental retardation. Am J Hum Genet. 2012 Jul 13;91(1):146-51. doi: 10.1016/j.ajhg.2012.05.004. Epub 2012 Jun 7. (
  • NCBI Gene (
  • Tsai YH, Liu X, Seeberger PH. Chemical biology of glycosylphosphatidylinositol anchors. Angew Chem Int Ed Engl. 2012 Nov 12;51(46):11438-56. doi: 10.1002/anie.201203912. Epub 2012 Oct 19. Review. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: August 2013
Published: February 1, 2016