A disease or condition caused by an absent or defective gene or by a chromosomal aberration & Genetic disorders may be hereditary. Sometimes there is a mutation, a change in a gene or genes. Most genetic diseases are directly caused by a mutation in one gene, however no specific gene can clarify whether someone has disorder or not. This is quite important to find out how genes contribute to diseases that have a complex pattern of inheritance, such as in the case of diabetes, asthma, cancer & mental illness. This can cause a medical condition called a genetic disorder. You can inherit a gene mutation from one or both parents. A mutation can also happen during your lifetime. Genetic tests on blood and other tissue can identify disorders, accordingly.
There are three types of genetic disorders:
- Single-gene disorders, where a mutation affects one gene for example Sickle cell anemia.
- Chromosomal disorders, where chromosomes (or parts of chromosomes) are missing or changed. Chromosomes are the structures that hold our genes. Down syndrome is a chromosomal disorder.
- Complex disorders, where there are mutations in two or more genes. Often your lifestyle and environment also play a significant role. Colon cancer can be counted as an example.