Single-gene disorders, also known as monogenic disorders, are genetic disorders that are caused by mutations in a single gene. These mutations can be inherited from one or both parents or can occur spontaneously during cell division.
Single-gene disorders can be classified into several categories based on the inheritance pattern of the mutation:
- Autosomal dominant disorders: These disorders are caused by a mutation in a single copy of an autosomal gene. An affected individual has a 50% chance of passing the mutation on to their offspring. Examples of autosomal dominant disorders include Huntington’s disease and Marfan syndrome.
- Autosomal recessive disorders: These disorders are caused by mutations in both copies of an autosomal gene. An affected individual inherits one mutated copy of the gene from each parent. Examples of autosomal recessive disorders include cystic fibrosis and sickle cell anemia.
- X-linked dominant disorders: These disorders are caused by mutations in genes on the X chromosome. Females are more likely to be affected than males because they have two X chromosomes. Examples of X-linked dominant disorders include Rett syndrome and vitamin D-resistant rickets.
- X-linked recessive disorders: These disorders are caused by mutations in genes on the X chromosome. Males are more likely to be affected than females because they only have one X chromosome. Examples of X-linked recessive disorders include hemophilia and Duchenne muscular dystrophy.
Diagnosis of single-gene disorders often involves genetic testing to identify the specific mutation responsible for the disorder. Treatment options may include medication, dietary changes, and/or surgery, depending on the specific disorder and its symptoms. In some cases, genetic counseling may also be recommended to help individuals and their families understand the risk of passing the mutation on to future generations.