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Reviewed August 2015

What is the official name of the PHKG2 gene?

The official name of this gene is “phosphorylase kinase, gamma 2 (testis).”

PHKG2 is the gene's official symbol. The PHKG2 gene is also known by other names, listed below.

Read more about gene names and symbols on the About page.

What is the normal function of the PHKG2 gene?

The PHKG2 gene provides instructions for making one piece, the gamma subunit, of the phosphorylase b kinase enzyme. This enzyme is made up of 16 subunits, four each of the alpha, beta, gamma, and delta subunits. (Each subunit is produced from a different gene.) The gamma subunit performs the function of phosphorylase b kinase enzyme, and the other subunits help regulate its activity. This enzyme is found in various tissues, although it is most abundant in the liver and muscles. One version of the enzyme is found in liver cells and another in muscle cells. The gamma-2 subunit produced from the PHKG2 gene is part of the enzyme found in the liver.

Phosphorylase b kinase plays an important role in providing energy for cells. The main source of cellular energy is a simple sugar called glucose. Glucose is stored in muscle and liver cells in a form called glycogen. Glycogen can be broken down rapidly when glucose is needed, for instance to maintain normal levels of glucose in the blood between meals. Phosphorylase b kinase turns on (activates) another enzyme called glycogen phosphorylase b by converting it to the more active form, glycogen phosphorylase a. When active, this enzyme breaks down glycogen.

How are changes in the PHKG2 gene related to health conditions?

glycogen storage disease type IX - caused by mutations in the PHKG2 gene

At least 30 mutations in the PHKG2 gene are known to cause a form of glycogen storage disease type IX (GSD IX) called GSD IXc. This form of the disorder affects liver function and causes an enlarged liver (hepatomegaly), slow growth, and periods of low blood sugar (hypoglycemia) in affected individuals. These features usually improve over time. However, PHKG2 gene mutations have been associated with more severe signs and symptoms such as irreversible liver disease (cirrhosis).

Mutations in the PHKG2 gene reduce the activity of phosphorylase b kinase in liver cells, although the mechanism is unknown. Reduction of this enzyme's function impairs glycogen breakdown. As a result, glycogen builds up in cells, and glucose is not available for energy. The inability to break down glycogen in the liver causes the features of GSD IXc.

Where is the PHKG2 gene located?

Cytogenetic Location: 16p11.2

Molecular Location on chromosome 16: base pairs 30,748,299 to 30,761,176

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBIThis link leads to a site outside Genetics Home Reference.)

The PHKG2 gene is located on the short (p) arm of chromosome 16 at position 11.2.

The PHKG2 gene is located on the short (p) arm of chromosome 16 at position 11.2.

More precisely, the PHKG2 gene is located from base pair 30,748,299 to base pair 30,761,176 on chromosome 16.

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

Where can I find additional information about PHKG2?

You and your healthcare professional may find the following resources about PHKG2 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 PHKG2 gene or gene products?

  • GSD9C
  • PHK-gamma-T
  • phosphorylase b kinase gamma catalytic chain, testis/liver isoform
  • phosphorylase kinase, gamma 2 (testis/liver)
  • phosphorylase kinase subunit gamma-2
  • PSK-C3
  • serine/threonine-protein kinase PHKG2

Where can I find general information about genes?

The Handbook provides basic information about genetics in clear language.

These links provide additional genetics resources that may be useful.

What glossary definitions help with understanding PHKG2?

breakdown ; catalytic ; cirrhosis ; domain ; enzyme ; gene ; glucose ; glycogen ; hypoglycemia ; kinase ; muscle cells ; protein ; serine ; simple sugar ; subunit ; testis ; threonine

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

See also Understanding Medical Terminology.

References (7 links)


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 2015
Published: February 1, 2016