More than two dozen companies market home genetic tests for disease, other genetic traits and ancestry, while some offer "whole genome scans."

In an commentary in the Journal of the American Medical Association, Dr. Kenneth Offit, chief of the Clinical Genetics Service at Memorial Sloan-Kettering Cancer Center in New York, voices concerns about the scientific accuracy of some of these tests.

"They have not yet been validated in forward looking -- prospective -- clinical studies," Offit said in a statement.

The direct-to-consumer aspect of the tests, excludes guidance from healthcare professionals, Offit says.

"This raises concerns that patients/individuals may not have the resources to make unbiased decisions regarding whether to proceed with genetic testing," he said.

Offit says once self-ordered test results are relayed, individuals receiving the results may not also receive counseling regarding appropriate medical interventions for prevention and early detection of genetic disorders.

Some states, such as New York, require genetic testing for disease risk must be requested by a licensed healthcare professional and must be performed in an approved clinical laboratory, Offit says.