The main types of genetic tests:

Chromosomal: These tests help identify large genetic changes, such as an extra copy of a chromosome, causing a genetic condition. For this, whole chromosomes or long lengths of DNA are studied.
Molecular: DNA sequences are studied to identify variations (mutations) in genes that can cause or increase the risk of a genetic disorder. These tests can be narrow, which analyze an individual DNA building block (nucleotide) in one or more genes, or they can be large in scope, which analyzes all of a person’s DNA (known as their genome).
Gene expression: These tests show which genes are turned on or off in different cell types. Overexpression (too much activity) or underexpression (too little activity) of certain genes may indicate a genetic disorder.
Biochemical: These tests don’t analyze DNA directly, but they study the number of proteins and enzymes or their level of activity. Abnormalities in the results can indicate changes to the DNA that can cause a genetic disorder.
Screening: These tests are only estimates that determine the likelihood of a person developing a certain genetic condition compared to other people in a similar population. So a positive screening test result doesn’t confirm the presence of the disease, it only indicates that a person’s risk of developing the genetic condition is higher than average.

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