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Reviewed July 2009

What is the official name of the FAM126A gene?

The official name of this gene is “family with sequence similarity 126 member A.”

FAM126A is the gene's official symbol. The FAM126A 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 FAM126A gene?

The FAM126A gene provides instructions for making a protein called hyccin, which is active (expressed) throughout the nervous system. Researchers believe that hyccin is involved in the formation of myelin, which is the covering that protects nerves and promotes the efficient transmission of nerve impulses. Hyccin is also active in the lens of the eye, the heart, and the kidneys; however, the protein's function in these tissues is unclear.

How are changes in the FAM126A gene related to health conditions?

hypomyelination and congenital cataract - caused by mutations in the FAM126A gene

At least four mutations in the FAM126A gene have been found to cause hypomyelination and congenital cataract. Most mutations delete a large portion of the gene or create a premature stop signal in the instructions for making hyccin. These mutations prevent the production of any functional protein. One FAM126A gene mutation allows some protein to be produced. This mutation replaces the protein building block (amino acid) leucine with the amino acid proline at position 53 in the hyccin protein (written as Leu53Pro or L53P). People with the Leu53Pro mutation tend to have milder symptoms than those with mutations that prevent the production of any protein.

Any disruption in the production of hyccin impairs its role in the formation of myelin, leading to neurological problems such as intellectual disability and walking difficulties. It is unclear how a lack of hyccin causes a clouding of the lens (cataract) in both eyes that is typically present from birth in affected individuals. The neurological problems and cataracts are the characteristic features seen in people with hypomyelination and congenital cataract.

Where is the FAM126A gene located?

Cytogenetic Location: 7p15.3

Molecular Location on chromosome 7: base pairs 22,895,848 to 23,014,195

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

The FAM126A gene is located on the short (p) arm of chromosome 7 at position 15.3.

The FAM126A gene is located on the short (p) arm of chromosome 7 at position 15.3.

More precisely, the FAM126A gene is located from base pair 22,895,848 to base pair 23,014,195 on chromosome 7.

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

Where can I find additional information about FAM126A?

You and your healthcare professional may find the following resources about FAM126A 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 FAM126A gene or gene products?

  • family with sequence similarity 126, member A
  • HCC
  • HLD5
  • HYCC1
  • hyccin

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 FAM126A?

amino acid ; cataract ; congenital ; disability ; expressed ; gene ; leucine ; mutation ; nervous system ; neurological ; proline ; protein

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

See also Understanding Medical Terminology.

References (6 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: July 2009
Published: February 8, 2016