Carrier testing is a type of genetic testing that is used to determine if a person is a carrier for specific autosomal recessive diseases. This kind of testing is used most often by couples who are considering becoming pregnant to determine the risks of their child inheriting one of these genetic disorders. Background Genes come in pairs; one from the mother and one from the father. A carrier is a person who inherited one abnormal gene from one of their parents. Carriers often show no symptoms of the genetic disorder that they carry an abnormal gene for. Usually the only time a person finds out that they are a carrier for a specific genetic disorder is when they have an affected child. For these kinds of genetic diseases to be present in a person, two copies of the abnormal gene are needed. This means that both of the parents have to be a carrier for the child to inherit the disease. Reasons for testing The most common reason for carrier testing to allow future parents to find out if they are a carrier for a genetic disorder. If the parents are a carrier for a genetic disorder they can know ahead of time what their probability is of having an affected child. Carrier testing can be done before or during the pregnancy. Many of these genetic disease are fatal at a young age which oftentimes encourages parents to get tested. Autosomal recessive disorders/diseases There are hundreds of recessive genetic disorders, most of which are very rare. Certain genetic disorders tend to be more common in people of a particular ethnicity. For example, people of African American ethnicity have a much higher likelihood of being a carrier for the autosomal recessive disorder called sickle cell anemia. People of one ethnicity in particular, Ashkenazi Jewish, have a tendency to be carriers for a wide variety of recessive genetic disorders. There are also several recessive disorders that are present in all ethnicities. This list includes: cystic fibrosis, fragile X syndrome, and spinal muscular atrophy. Testing methods Carrier testing is most often done through a simple blood test. The results from these tests are usually available anywhere between two and eight weeks depending on where the testing is conducted. Some tests may screen for one or a few genetic conditions, and other tests may screen for hundreds. For example, in Australia, multiple companies offer