Genetic testing reimbursement presupposes that the testing is reasonable and necessary for the diagnosis or treatment of an established condition, that is, where signs and symptoms of a condition are already detectable to the patient and/or doctor.  This condition in the statute expressly denies coverage where no signs or symptoms are present, but simply where there may be curiosity about risk.
Such a limitation excludes the diagnostic testing for the medical risk of diseases, with only a few exceptions.  The Centers for Disease Control has published a detailed description of the limited, covered screening tests for risk. 
It is widely known that direct analysis of a patient’s chromosomes, or a patient’s genes – where personal and specific genetic information can be studied – may uncover clues to an individual’s risk of disease or the risk a person may transmit such a condition to a next generation family member.  
Medical genetics counselling centers openly solicit patients to undergo risk assessment, especially where a family history of genetic disease is prominent; this is a common practice where there is a high genetic risk of cancer. 
However, most genetic testing which is currently marketed to Medicare beneficiaries has no value for the patient, because such testing does not apply and guide therapy for a beneficiary’s current conditions or symptoms, but provides rather for guidance on family risk, that is to individuals in the next generation. The Office of the Inspector General clarified this limitation by stating “Medicare does not pay for preventive screening tests except those specifically authorized by statute. Since CMS considers predictive tests to be screening tests, genetic tests for this purpose are not covered by Medicare.” 
To assist patients in deciding whether to undergo such testing, a Medicare administrative contractor – Novitas Solutions – has published a guide to the limited, useful DNA testing which is reasonable and necessary and covered in the Novitas jurisdiction under the Medicare statute. Of approximately 50 currently available tests, about half are covered, but only with strict conditions.  Other Medicare contractors have provided similar notice on limitations of genetic testing.
A recent analysis of the limited value of genetic testing has been published in The Annals of Internal Medicine entitled, “The Deceptive Appeal of Direct to Consumer Genetics.”  The authors point out that the recent completion of the “Human Genome Project”, a National Institutes of Health initiative to study 100% of human genes  , has created a marketing opportunity that has been taken up by commercial laboratories through “direct-to-consumer” marketing.
The mapping of the human genome is one of the monumental achievements of science. However, as of yet, the utility of the information in this project for the promise of the Medicare statute to mitigate explicit illness, signs, and symptoms of disease must be considered limited at best.
To further understand the ongoing concern by the US Department of Health and Human Services vis-à-vis “Genetic Testing Scams,” one should review the 2019 OIG Report. It admonished:
The U.S. Department of Health and Human Services Office of Inspector General is alerting the public about a fraud scheme involving genetic testing. Genetic testing fraud occurs when Medicare is billed for a test or screening that was not medically necessary and/or was not ordered by a Medicare beneficiary’s treating physician. The Advisory, inter alia, warned that scammers were offering Medicare beneficiaries “free” screenings or cheek swabs for genetic testing in order to obtain their Medicare information for identity theft or fraudulent billing purposes… through telemarketing calls, booths at public events, health fairs, and door-to-door visits, even if it is not ordered by a physician or medically necessary. Substantial penalties may be brought to bear against perpetrators of such costly fraud.
Indeed, Kaiser Health News estimated that unnecessary medical testing, including fraudulent schemes as discussed above, may cost the US economy in excess of $200 billion annually.
Medicare contractors issue local coverage determinations that are available on the CMS website. However, medical necessity is often unchecked without a file review, which is unfortunately almost never conducted absent repeated and robust allegations of fraud against a particular target. The opportunity for systematic and widespread genetic testing fraud continues!
 https://www.cms.gov/Outreach-and-Education/Medicare-Learning-Network-MLN/MLNProducts/Downloads/Items-and-Services-Not-Covered-Under-Medicare-Booklet-ICN906765.pdf , pages 1-2.