Introduction to Gene Mutations in Humans
Basics Covering the Types of Changes in the DNA Sequence
Apr 19, 2009
Mutations are changes in DNA that sometimes affect how genes do their jobs. Genes are instructions, and if these instructions are damaged, the end result is not as it should be. It can be compared to a recipe, where mistakes can lead to the recipe failing either in part or in full.
Mutations can affect small or large amounts of genetic material. Most mutations are harmless, and some, called silent mutations, don’t have any effect. Rarely, mutations can cause serious problems with health and development, whereas others actually benefit and will prevail in populations through natural selection.
Types of Mutations – Hereditary, De Novo and Somatic
Some types of mutations include:
- Hereditary – also called germ line mutations, these mutations occur in the sex cells (sometimes referred to as “germ cells”) and are therefore passed on from parent to offspring.
- De novo – also called “new” or “spontaneous” mutations, de novo mutations occur in sex cells during or after fertilization.
- Somatic – also called acquired mutations, these happen to individuals in their lifetime. A mistake may be made when the DNA is being copied to make new cells, or via environmental damage, such as UV radiation. Since only somatic (body) cells are affected, such mutations cannot be inherited.
Gene Mutations and Health and Development
Gene mutations can lead to severe health problems, such as cystic fibrosis, sickle cell anemia and Tay-Sachs disease. Many genetic disorders are recessive, meaning the individual would have to have two copies of the mutated gene (one from each parent) in order to have the disease.
The Genetics Home Reference’s article Mutations and Health says, “It is important to note that genes themselves do not cause disease — genetic disorders are caused by mutations that make a gene function improperly.” They give the example of the cystic fibrosis gene (CFTR). Those with cystic fibrosis don’t have a gene unique to them, but a mutated version of a gene everyone shares.
Read Basic Cell Biology for Understanding Genetics for more information on DNA, genes and somatic cells. For the basics behind genetic testing, read Understanding Genetic Testing in Healthcare. The Genetics Home Reference website section on Mutations and Health is suitable for beginners, and covers gene mutations in detail.
Sources
Mutations and Health, Genetics Home Reference, published: 10th April 2009, accessed: 18th April 2009, no author specified.
30 New Mutations per Lifetime (Blazing a Genetic Trail), Howard Hughes Medical Institute website, accessed: 18th April 2009, no author specified.
When Genes Go Bad: Mutations and Disease, The Tech’s Understanding Genetics website, accessed: 18th April 2009, no author specified.
 |
