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Reviewed September 2010

What is the official name of the PYGL gene?

The official name of this gene is “phosphorylase, glycogen, liver.”

PYGL is the gene's official symbol. The PYGL 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 PYGL gene?

The PYGL gene provides instructions for making an enzyme called liver glycogen phosphorylase. This enzyme breaks down a complex sugar called glycogen. Liver glycogen phosphorylase is one of three related enzymes that break down glycogen in cells; the other glycogen phosphorylases are found in the brain and in muscles. Liver glycogen phosphorylase is found only in liver cells, where it breaks down glycogen into a type of sugar called glucose-1-phosphate. Additional steps convert glucose-1-phosphate into glucose, a simple sugar that is the main energy source for most cells in the body.

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

glycogen storage disease type VI - caused by mutations in the PYGL gene

At least 17 mutations in the PYGL gene have been found to cause glycogen storage disease type VI (GSDVI). Most mutations change single protein building blocks (amino acids) in liver glycogen phosphorylase, affecting the normal function of the enzyme. In the Old Order Mennonite population, a common mutation (written as 1620+1G>A) disrupts the way the PYGL gene's instructions are used to make the enzyme. A defective liver glycogen phosphorylase enzyme impairs the normal breakdown of glycogen. As a result, liver cells cannot use glycogen for energy, so liver function becomes impaired. A lack of glycogen breakdown within liver cells leads to the major features of GSDVI.

Where is the PYGL gene located?

Cytogenetic Location: 14q21-q22

Molecular Location on chromosome 14: base pairs 50,905,217 to 50,944,530

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

The PYGL gene is located on the long (q) arm of chromosome 14 between positions 21 and 22.

The PYGL gene is located on the long (q) arm of chromosome 14 between positions 21 and 22.

More precisely, the PYGL gene is located from base pair 50,905,217 to base pair 50,944,530 on chromosome 14.

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

Where can I find additional information about PYGL?

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

  • glycogen phosphorylase, liver form
  • GSD6

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 PYGL?

acids ; breakdown ; enzyme ; gene ; glucose ; glycogen ; mutation ; phosphate ; population ; protein ; simple sugar

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

See also Understanding Medical Terminology.

References (5 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: September 2010
Published: February 8, 2016