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ASHG recommendations on ancestral / genealogical DTC genetic testing

1 December 2008   |   By Dr Philippa Brice   |   News story
A growing trend in the provision of direct-to-consumer (DTC) genetic testing for ancestry research has led the American Society of Human Genetics (ASHG) to issue new guidance, proposing that the practice needs greater scrutiny and that “it is imperative to explore the complex relationship between genetics, ancestry and race that can complicate the interpretation of these types of tests and their results” (see press release). This assertion is partly because many companies offer testing for both ancestral analysis and health risk assessment; because of the potentially wide-ranging impacts of such testing; and also because of the unaddressed scientific and non-scientific challenges and implications of DTC ancestry…in the genetic and genomic research arenas from which it originated”.In particular, they draw attention to the different applications of genetic ancestry analysis as a service for individual consumers as compared with in the context of large-scale scientific research on population genetics.

The ASHG statement on ancestry testing noted their major concern that there is no quality assurance system or even a mechanism to couple market performance with anything relating to accuracy”, although this accuracy could vary to a significant degree depending on the reference population databases used for analysis. The ASHG also notes that even the best databases “reflect a woefully incomplete sampling of human genetic diversity”. In terms of potential health implications of ancestry testing, the ASHG notes the current lack of understanding about how genetic ancestry related to individual and population health, along with a common assumption that racial/ethnic identity may be a key determinant of health outcomes. They urge caution in the interpretation and clinical application of results from ancestry and related DTC genetic tests. The personal and societal implications of testing are noted to be potentially complex, raising a range of political, legal, psychological, social and ethical issues.

President elect of the ASHG Edward McCabe commented: “Consumers, as well as scientists, must remember that ancestry-testing inferences are fallible, and that over-interpretation or misinterpretation can happen…Inaccurate results may be confusing and life-changing, therefore greater efforts are needed to make the limitations of ancestry testing more explicit” (see press release).

The five recommendations of the ASHG are:
  1. Clearer delineation of the current limitations of ancestry determination by industry and academia to make them clearer to consumers, the scientific community, and the public at large; the public should access and take note of information.
  2. Further research to clarify the extent to which the accuracy of genetic ancestry estimation is influenced by the individuals represented in existing databases, geographical patterns of human diversity, marker selection and statistical methods.
  3. Assessment of the complex consequences of ancestry estimation for people, families, and populations, and the development of guidelines to facilitate explanation and/or counselling about ancestry estimation in research, DTC and health care settings.
  4. Conferral of scientists performing and interpreting genetic ancestry tests with experts in the historical, sociopolitical and cultural contexts of such testing.
  5. Establishment of mechanisms for greater accountability of the DTC ancestry testing industry.

Internet-based ancestry testing is available DTC internationally; for example, MyHeritage offers testing including a Y-chromosome test to identify paternal descent, a mitochondrial DNA test to identify maternal descent. FamilyTreeDNA chief executive Bennett Greenspan has reportedly said of their own service: "The biggest problem is finding out your brother isn't your brother or your father isn't your father. But we don't deal with that…you'd be more likely to find out that your great grandfather was adopted or that there was false paternity" (see Guardian news article).

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