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


Reviewed June 2008

What is the official name of the PNPO gene?

The official name of this gene is “pyridoxamine 5'-phosphate oxidase.”

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

What is the normal function of the PNPO gene?

The PNPO gene provides instructions for producing an enzyme called pyridoxine 5'-phosphate oxidase. This enzyme is involved in the breakdown (metabolism) of vitamin B6. Specifically, it chemically modifies two forms of vitamin B6 derived from food (pyridoxine and pyridoxamine) to form pyridoxal 5'-phosphate (PLP). PLP is the active form of vitamin B6 and is necessary for many processes in the body, including protein metabolism and the production of chemicals that transmit signals in the brain (neurotransmitters). Pyridoxine 5'-phosphate oxidase is active (expressed) in cells throughout the body, with the highest amounts found in the liver.

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

pyridoxal 5'-phosphate-dependent epilepsy - caused by mutations in the PNPO gene

At least 7 mutations in the PNPO gene have been found to cause pyridoxal 5'-phosphate-dependent epilepsy. Most of these mutations change one protein building block (amino acid) in the pyridoxine 5'-phosphate oxidase enzyme, impairing its normal function. The resulting enzyme cannot effectively metabolize pyridoxine and pyridoxamine to produce PLP. A shortage of PLP can disrupt the function of many other proteins and enzymes that need PLP in order to be effective. It is not clear how the lack of PLP affects the brain and leads to the seizures that are characteristic of this condition.

Where is the PNPO gene located?

Cytogenetic Location: 17q21.32

Molecular Location on chromosome 17: base pairs 47,941,523 to 47,949,308

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

The PNPO gene is located on the long (q) arm of chromosome 17 at position 21.32.

The PNPO gene is located on the long (q) arm of chromosome 17 at position 21.32.

More precisely, the PNPO gene is located from base pair 47,941,523 to base pair 47,949,308 on chromosome 17.

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

Where can I find additional information about PNPO?

You and your healthcare professional may find the following resources about PNPO 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 PNPO gene or gene products?

  • FLJ10535
  • pyridoxine 5'-phosphate oxidase

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

What glossary definitions help with understanding PNPO?

amino acid ; breakdown ; enzyme ; epilepsy ; expressed ; gene ; metabolism ; neurotransmitters ; oxidase ; phosphate ; protein

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


  • Kang JH, Hong ML, Kim DW, Park J, Kang TC, Won MH, Baek NI, Moon BJ, Choi SY, Kwon OS. Genomic organization, tissue distribution and deletion mutation of human pyridoxine 5'-phosphate oxidase. Eur J Biochem. 2004 Jun;271(12):2452-61. (
  • Mills PB, Surtees RA, Champion MP, Beesley CE, Dalton N, Scambler PJ, Heales SJ, Briddon A, Scheimberg I, Hoffmann GF, Zschocke J, Clayton PT. Neonatal epileptic encephalopathy caused by mutations in the PNPO gene encoding pyridox(am)ine 5'-phosphate oxidase. Hum Mol Genet. 2005 Apr 15;14(8):1077-86. Epub 2005 Mar 16. (
  • Musayev FN, Di Salvo ML, Ko TP, Schirch V, Safo MK. Structure and properties of recombinant human pyridoxine 5'-phosphate oxidase. Protein Sci. 2003 Jul;12(7):1455-63. (
  • NCBI Gene (


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: June 2008
Published: February 8, 2016