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Reviewed August 2012

What is the official name of the C9orf72 gene?

The official name of this gene is “chromosome 9 open reading frame 72.”

C9orf72 is the gene's official symbol. The C9orf72 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 C9orf72 gene?

The C9orf72 gene provides instructions for making a protein that is found in many tissues but whose function is unknown. Three different versions (isoforms) of the C9orf72 protein are produced from the C9orf72 gene. These isoforms are likely found in different tissues, but their purpose is unclear. The C9orf72 protein is produced in many regions of the brain. Within nerve cells (neurons), the protein is found in the fluid surrounding the nucleus (the cytoplasm). Additionally, the C9orf72 protein seems to be located in specialized structures called presynaptic terminals, found at the tips of neurons.

How are changes in the C9orf72 gene related to health conditions?

amyotrophic lateral sclerosis - caused by mutations in the C9orf72 gene

Mutations in the C9orf72 gene have been found to cause amyotrophic lateral sclerosis (ALS), a condition characterized by progressive movement problems and muscle wasting. The normal C9orf72 gene contains a region where a series of six DNA building blocks (nucleotides) occurs once or can be repeated multiple times. This stretch of nucleotides consists of four guanines and two cytosines (written as GGGGCC). When this series of nucleotides is repeated too many times, it can cause ALS. This type of mutation is called a hexanucleotide repeat expansion. Although it is not clear exactly how many hexanucleotide repeats are needed to cause disease, researchers believe that having more than about 30 repeats can lead to ALS. The hexanucleotide repeat expansion in the C9orf72 gene appears to reduce the amount of C9orf72 protein that is produced. The protein that is produced may be altered and may interfere with cell function. It is unclear how decreased or altered C9orf72 protein causes the signs and symptoms of ALS.

Some people with ALS caused by C9orf72 gene mutations also develop a condition called frontotemporal dementia (FTD), which is a progressive brain disorder that affects personality, behavior, and language. It is unclear why some people with C9orf72 gene mutations develop FTD and others do not. Individuals who develop both conditions are diagnosed as having ALS-FTD.

Where is the C9orf72 gene located?

Cytogenetic Location: 9p21.2

Molecular Location on chromosome 9: base pairs 27,546,546 to 27,573,866

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

The C9orf72 gene is located on the short (p) arm of chromosome 9 at position 21.2.

The C9orf72 gene is located on the short (p) arm of chromosome 9 at position 21.2.

More precisely, the C9orf72 gene is located from base pair 27,546,546 to base pair 27,573,866 on chromosome 9.

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

Where can I find additional information about C9orf72?

You and your healthcare professional may find the following resources about C9orf72 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 C9orf72 gene or gene products?

  • CI072_HUMAN
  • MGC23980
  • uncharacterized protein C9orf72
  • uncharacterized protein C9orf72 isoform a
  • uncharacterized protein C9orf72 isoform b

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 C9orf72?

cell ; chromosome ; cytoplasm ; dementia ; DNA ; gene ; isoforms ; mutation ; nucleus ; open reading frame ; presynaptic ; protein ; reading frame ; sclerosis ; wasting

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: August 2012
Published: February 8, 2016