Genetic tests look for alterations in a person’s genes or changes in the level or structure of key proteins coded for by specific genes. Genetic tests can also be used to look at levels of RNA that play a role in certain conditions. Abnormal results on these tests could mean that someone has a genetic disorder.

Types of genetic tests include:

Gene tests (individual genes or relatively short lengths of DNA or RNA are tested)

Chromosomal tests (whole chromosomes or very long lengths of DNA are tested)

Biochemical tests (protein levels or enzyme activities are tested)

Gene tests look at individual genes or short lengths of DNA or RNA. These tests look for signs of a disease or disorder in DNA or RNA. The sample uses blood or other body fluids such as saliva or tissue. These tests look for abnormalities in genes – genes that have a section missing; genes that have a section added, or small changes like missing, added, or altered chemicals within the DNA strand.
Chromosomal tests look for abnormalities in a person’s chromosomes, including: pieces of a chromosome being deleted, expanded, or being switched to a different chromosomal location.
Biochemical tests look at the amounts or activities of key proteins.  Since genes contain the DNA code for making proteins, abnormal amounts or activities of proteins can be a signal that some genes are not working normally.