2020–2021 BCSC Basic and Clinical Science Course™
2 Fundamentals and Principles of Ophthalmology
Part III: Genetics
Chapter 6: Clinical Genetics
Recommendations for Genetic Testing of Inherited Eye Disease
The AAO Task Force on Genetic Testing has stated that when properly performed, interpreted, and acted upon, genetic tests can improve the accuracy of diagnosis, prognosis, and genetic counseling; can lead to reduced risk of disease recurrence in families at risk; and can facilitate the delivery of personalized care. Like other forms of medical intervention, genetic testing carries specific risks that vary from patient to patient and from family to family. The results of a genetic test may affect plans to have children, create guilt or anxiety, and complicate family relationships. For these reasons, skilled counseling should be provided to all individuals who undergo genetic testing in order to maximize benefits and minimize risks.
The task force’s 7 recommendations are as follows:
Offer genetic testing to patients with clinical findings suggestive of a mendelian disorder whose causative gene(s) have been identified. If unfamiliar with such testing, refer the patient to a physician or counselor who is familiar with it. In all cases, ensure that the patient receives counseling from a physician with expertise in inherited disease or a certified genetic counselor.
Use Clinical Laboratories Improvement Amendments (CLIA)–approved laboratories for all clinical testing. When possible, use laboratories that include in their reports estimates of the pathogenicity of observed genetic variants that are based on a review of the medical literature and databases of disease-causing and nondisease-causing variants.
Provide a copy of each genetic test report to the patient so that she or he can independently seek mechanism-specific information, such as the availability of genespecific clinical trials, should the patient wish to do so.
Avoid direct-to-consumer genetic testing and discourage patients from obtaining such tests themselves. Encourage the involvement of a trained physician, genetic counselor, or both for all genetic tests so that appropriate interpretation and counseling can be provided.
Avoid unnecessary parallel testing; order the most specific test(s) available, given the patient’s clinical findings. Restrict massively parallel strategies like whole-exome sequencing and whole-genome sequencing to research studies conducted at tertiary care facilities.
Avoid routine genetic testing for genetically complex disorders like age-related macular degeneration and late-onset primary open-angle glaucoma until specific treatment or surveillance strategies have been shown in one or more published prospective clinical trials to be of benefit to individuals with specific disease-associated genotypes. In the meantime, confine the genotyping of such patients to research studies.
Avoid testing asymptomatic minors with untreatable disorders except in extraordinary circumstances. For the few cases in which such testing is believed to be warranted, the following steps should be taken before the test is performed: (a) the parents and child should undergo formal genetic counseling; (b) the certified counselor or physician performing the counseling should state his or her opinion in writing that the test is in the family’s best interest; and (c) all parents with custodial responsibility for the child should agree in writing with the decision to perform the test.
Excerpted from BCSC 2020-2021 series: Section 2 - Fundamentals and Principles of Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.