ARHI

The ARHI gene is a member of a family of genes called ras. Genes in this family play an important role in the control of cell growth and the determination of cell type. Like other members of the ras gene family, ARHI is involved in regulating cell growth. ARHI differs from other ras family genes, however, in that it probably acts as a tumor suppressor. Tumor suppressor genes regulate the cycle of cell division by keeping cells from growing and dividing too fast or in an uncontrolled way.

The ARHI gene makes a protein called ras homolog I. This protein is located in the cytoplasm (the fluid inside of cells) and the cell membrane of normal cells in the breasts and ovaries. The ras homolog I protein probably regulates the growth of cells by interacting with proteins that control the cell division cycle.

One copy of the ARHI gene—the copy inherited from a person's mother—is silent (nonfunctional) throughout life. Only the copy inherited from a person's father is active. ARHI is the first tumor suppressor gene with this property known to be involved in adult human cancers.

breast cancer - associated with the ARHI gene

Research has shown that ARHI gene function is often lost in breast cancer cells. Because one copy of the gene is normally inactive, an error in the single active copy can lead to a nonfunctional gene. Possible errors include the deletion of a piece of chromosome 1 containing the gene and mutations in the gene itself. An absent or defective ARHI gene does not produce any functional ras homolog I protein to regulate cell growth, which could cause cells in the breast to grow and divide uncontrollably and form a tumor.

ovarian cancer - associated with the ARHI gene

The ARHI gene is often nonfunctional in ovarian cancer cells, possibly due to loss or inactivation of the paternal copy of this gene. As in breast cancer cells, this loss of gene function could allow cells in the ovaries to grow and divide uncontrollably and form a tumor.

1p31

The ARHI gene is located on the short (p) arm of chromosome 1 at position 31.

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

You may also be interested in these resources, which are designed for genetics professionals and researchers.

• PubMed - Recent literature
• OMIM - Genetic disorder catalog
• Research Resources - Tools for researchers (3 links)

See How are genetic conditions and genes named? in the Handbook.

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• What is DNA?
• What is a gene?
• How does a gene make a protein?
• How can gene mutations cause disorders?

These links provide additional genetics resources that may be useful.

• Genetics education
• Human Genome Project
• Resources for Genetic Researchers

cancer ; cell division ; cell division cycle ; cell membrane ; chromosome ; cytoplasm ; deletion ; gene ; homologs ; mutation ; protein ; RAS ; RAS gene family ; tumor ; tumor suppressor gene

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