Spontaneous, induced and hereditary mutations can cause human disease. Mutations are permanent changes to the genetic material of a cell, if mutation occurs in the human germline it can be transmissible to subsequent generations. Mutation can affect human health causing disease by disrupting a cell's normal biological functions.

Changes in the DNA caused by mutation can cause errors in protein. To function correctly, each cell depends on thousands of proteins to function in the right places at the right times. Sometimes, gene mutations prevent one or more of these proteins from functioning correctly, causing malfunction or loss of a necesary protein. When a mutation alters a protein that plays a critical role in the body, a medical condition can result. A condition caused by mutations in one or more genes is called a genetic disorder.

Genes themselves do not cause disease, genetic disorders are caused by mutations that make a gene function improperly. For example, when people say that someone has “the cystic fibrosis gene,” they are usually referring to a mutated version of the CFTR gene, which causes the disease. All people, including those without cystic fibrosis, have a version of the CFTR gene.

Only a small percentage of mutations cause genetic disorders, most have no impact on health. For example, some mutations alter a gene's DNA base sequence but don’t change the amino acid (silent mutation) or if a codon change alters and amino acid in a protein it may not affect function of the protein made by the gene.

Often, gene mutations that could cause a genetic disorder are repaired by the cell's DNA repair enzymes before the gene is expressed (makes a protein). Each cell has a number of pathways through which enzymes recognize and repair mistakes in DNA. Because DNA can be damaged or mutated in many ways, the process of DNA repair is an important way in which the body protects itself from disease.

See also

• Genetic disorder

This article incorporates public domain text from The U.S. National Library of Medicine (http://ghr.nlm.nih.gov)