Final answer:
Genetic counselors use mouth cell samples for DNA testing because they are non-invasive, easily accessible, and contain complete genetic information. These tests can reveal carrier status for genetic disorders and are complemented by prenatal testing methods like amniocentesis when necessary.
Step-by-step explanation:
Why Genetic Counselors Use Mouth Cell Samples for DNA Testing
Genetic counselors often obtain cell samples from a couple's mouth instead of using sperm or egg cells to determine the risk of genetic disorders in their offspring because mouth cells, like any other body cells, contain a complete set of DNA that represents the individual's genetics. This DNA can be used to test for carrier status of genetic conditions such as Fragile X or cystic fibrosis, and for chromosomal disorders.
The sample is easily accessible, non-invasive, and as informative as sampling sperm or egg cells would be. Furthermore, genetic counselors help couples understand test implications, cope with the discovery of being a carrier, and evaluate risks for potential chromosomal disorders in their offspring.
Genetic counselors utilize other methods such as amniocentesis or chorionic villus sampling for prenatal testing, which assesses if the fetus has genetic abnormalities. A blood test is another common method for genetic testing. These tests can help detect mutations associated with a variety of disorders and cancers, such as defects in the BRCA1 and BRCA2 genes related to breast cancer.