Reviewed September 2008
What is the official name of the HEXA gene?
The official name of this gene is “hexosaminidase A (alpha polypeptide).”
HEXA is the gene's official symbol. The HEXA gene is also known by other names, listed below.
What is the normal function of the HEXA gene?
The HEXA gene provides instructions for making one part (subunit) of an enzyme called beta-hexosaminidase A. Specifically, the protein produced from the HEXA gene forms the alpha subunit of this enzyme. One alpha subunit joins with one beta subunit (produced from the HEXB gene) to form a functioning enzyme.
Beta-hexosaminidase A plays a critical role in the brain and spinal cord (central nervous system). This enzyme is found in lysosomes, which are structures in cells that break down toxic substances and act as recycling centers. Within lysosomes, beta-hexosaminidase A forms part of a complex that breaks down a fatty substance called GM2 ganglioside.
How are changes in the HEXA gene related to health conditions?
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Tay-Sachs disease - caused by mutations in the HEXA gene
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More than 120 mutations that cause Tay-Sachs disease have been identified in the HEXA gene. These mutations reduce or eliminate the activity of the enzyme beta-hexosaminidase A, which prevents the enzyme from breaking down GM2 ganglioside. As a result, this substance builds up to toxic levels, particularly in nerve cells in the brain and spinal cord. Progressive damage caused by the buildup of GM2 ganglioside leads to the destruction of these cells, which causes the signs and symptoms of Tay-Sachs disease.
Most of the known HEXA mutations result in a completely nonfunctional version of beta-hexosaminidase A. These mutations cause the severe form of Tay-Sachs disease, which appears in infancy. Other mutations reduce but do not eliminate the activity of beta-hexosaminidase A; these genetic changes are responsible for the less severe forms of Tay-Sachs disease, which appear later in life.
Where is the HEXA gene located?
Cytogenetic Location: 15q23-q24
Molecular Location on chromosome 15: base pairs 70,422,832 to 70,455,392
The HEXA gene is located on the long (q) arm of chromosome 15 between positions 23 and 24.
More precisely, the HEXA gene is located from base pair 70,422,832 to base pair 70,455,392 on chromosome 15.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about HEXA?
You and your healthcare professional may find the following resources about HEXA helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
- PubMed
- Recent literature
- OMIM - Genetic disorder catalog
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What other names do people use for the HEXA gene or gene products?
- Beta-hexosaminidase A
- beta-N-Acetylhexosaminidase A
- Hex A
- HEXA_HUMAN
- N-acetyl-beta-glucosaminidase
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 HEXA?
cell ;
central nervous system ;
enzyme ;
gene ;
lysosome ;
mutation ;
nerve cell ;
nervous system ;
polypeptides ;
protein ;
sign ;
subunit ;
symptom ;
toxic
You may find definitions for these and many other terms in the Genetics Home Reference
Glossary.
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.
