At present, diagnostic molecular genetic testing is commercially available for parkin and PINK1 gene mutations and can be done for selected patients. However, appropriate counseling should be provided either by the treating physician or a clinical geneticist, along with psychological support.
Commercial genetic testing for parkinsonian genes should be interpreted with caution. A positive finding contributes only to the probability that the person will become affected, because most mutations gain or lose function and are associated with age-dependent penetrance. Indeed, for most genes and mutations, the age-associated risk to carriers has yet to be formally described. Despite the explosive progress in genetic research, not all mutations in PD have been functionally validated and some rare variants could be benign polymorphisms. Technical problems in test-retest reliability may also occur. These issues should be carefully and comprehensively discussed with physicians and their patients who are seeking genetic advice, as well as with asymptomatic family members who are genealogically at risk.
Patients and their families must continue contributing to genetic research to identify new genes, understand the molecular pathways affected, and develop new treatments. However, this genetic testing can be de-identified and blinded to test results to help make more general advances. There are many centers in the United States, Europe, Asia, and Australia that conduct molecular genetic research in PD.
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