Genes are units of inheritance that code for traits and conditions, such as eye color or hair texture. Genes are located on structures called chromosomes. Individuals typically have 46 chromosomes that come in 23 pairs. One copy of each chromosome pair (and therefore each gene) comes from our mother and the other from our father. Similarly, we pass on one copy of each chromosome pair to our children.

Genes make proteins that are necessary for the proper growth and development of the body. Each gene is made up of an informational code called DNA. If you think of a gene as a very large book, DNA is the alphabet that makes up the words and sentences in the book. When a gene is altered, it simply means there is a typographical error (typo) in the book. This alteration (or "mutation") makes the gene unable to function properly. Alterations can be as large as an entire chapter missing from the book, or as small as a single letter change within a word.

Alterations in certain genes (called cancer predisposition genes) may increase an individual's chance to develop specific types of cancer. Please review the following disease-specific information sheets for details about some of the more common hereditary cancer predisposition syndromes.

Hereditary Breast and Ovarian Cancer
Lynch Syndrome (Hereditary Non-Polyposis Colorectal Cancer)
Hereditary Colorectal Cancer: Familial Adenomatous Polyposis
Hereditary Colorectal Cancer: MYH-Associated Polyposis