Molecular genetic testing is a powerful tool for the care of patients with genetic ocular conditions. Benefits include confirmation or ruling out of an underlying genetic disorder and determining the risk of inheriting or transmitting a genetic disease. Before testing, considerations include the target and goal of testing, cost, availability, possible unintended outcomes, risks, limitations, and benefits. There are many forms of genetic testing and the choice of a specific test must be based on knowledge of the likely target finding. Result analysis and disclosure is a complex process that often requires an experienced genetics team.
Molecular genetic testing is one of the cornerstones for the care of patients with genetic ocular disease and their families. The results of these tests provide many benefits, including confirmation or ruling out of an underlying genetic disorder or helping to determine the risk of inheriting a genetic disease. With many options for studying the genetic etiology of a disorder, one should consider the target and goal of testing, cost, availability, possible unintended outcomes, risks, limitations, and benefits.
Molecular tests can range from the search for a specific mutation in a single gene to sequencing of the entire genome. Chromosomal tests analyze whole chromosomes or specific lengths of deoxyribonucleic acid (DNA) to identify deletions, duplications, or rearrangements of chromosomal material. Biochemical tests study the quantity or functional level of proteins, which can suggest causative DNA changes that result in a specific disorder. In an ideal world, testing should be carried out before undergoing major operations such as cataract surgery.
Genetic testing is voluntary. Because these tests have benefits as well as risks, patients should always be well informed prior to the initiation of testing. A clinical/ ocular geneticist or genetic counselor can provide valuable information about the limitations, advantages and disadvantages of a particular test, risks (e.g., discovery of unreported nonpaternity, identification of a health risk unrelated to the indication for testing), and the potential social, insurance, and emotional implications of genetic testing. Counseling should also include information on the nature, inheritance, and implications of the genetic disorder for which testing is being ordered. Similar counseling should be performed after the results of the test become available.