Single gene disorder

Single gene disorder is a type of genetic disorder caused by changes or mutations in the DNA sequence of a single gene. These disorders are also known as monogenic disorders. There are thousands of known single gene disorders, which occur in about 1 out of every 200 births. Some examples include cystic fibrosis, sickle cell anemia, Marfan syndrome, Huntington's disease, and hemochromatosis.

Causes

Single gene disorders are caused by DNA changes in one particular gene, and can be passed along to an individual's offspring. There are three types of single gene disorders; dominant, recessive, and X-linked.

Dominant

A dominant disorder is caused by just one copy of a mutated gene. Even if the other copy of the gene is normal, the individual will still have the disorder. An example of a dominant disorder is Huntington's disease.

Recessive

A recessive disorder is caused by mutations in both copies of a gene. An individual must inherit two copies of the mutated gene - one from each parent - to have the disorder. An example of a recessive disorder is cystic fibrosis.

X-linked

An X-linked disorder is caused by mutations in a gene on the X chromosome. Males are more likely to have X-linked disorders because they have only one X chromosome, while females have two. An example of an X-linked disorder is hemophilia.

Diagnosis

Diagnosis of single gene disorders can be made through a variety of methods, including genetic testing, prenatal testing, and newborn screening. Genetic testing involves examining the DNA to look for mutations in specific genes. Prenatal testing can identify single gene disorders in the fetus during pregnancy. Newborn screening is a public health program that tests newborns for certain serious conditions at birth, including some single gene disorders.

Treatment

Treatment for single gene disorders depends on the specific disorder and the symptoms. Some treatments aim to manage the symptoms, while others aim to fix the underlying genetic problem. Treatments can include medications, surgery, physical therapy, and dietary changes. In some cases, gene therapy may be an option.

See also

• Genetic disorder
• Dominant gene
• Recessive gene
• X-linked gene
• Genetic testing
• Prenatal testing
• Newborn screening

Single gene disorder Resources
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