Tuesday, December 21, 2010

Genetic Testing for CDKN2A/p16

Genetic testing is a really confusing issue for many. It may present a clear and present danger for a few but for most it represents possibly but one step in a multiple step change.

As reported by Eureka on some recent research:

The study, led by Sancy A. Leachman, M.D., Ph.D., of the University of Utah Department of Dermatology and Lisa G. Aspinwall, Ph.D., of the University of Utah Department of Psychology, both HCI investigators, surveyed 61 adults tested for the CDKN2A/p16 mutation that increases the risk of melanoma. Overall, 86.9 percent expressed support for melanoma genetic testing of minors. They cited the importance of risk awareness and the likelihood of improved prevention and screening behavior as reasons for their support. Participants were surveyed when they received their genetic test results and again two years later; their attitudes remained stable over that period.

"Developing guidelines for genetic testing of minors is complex and controversial," says Leachman. "But knowledge of their genetic status could help them make appropriate lifestyle decisions. For example, a child who tested positive might decide not to choose a summer job that demands lots of sun exposure, such as lifeguard."

This is from a Genetics in Medicine article. They report:

Genetic testing of minors is controversial, as ethical considerations depend on multiple aspects of the particular disease and familial context. For melanoma, there is a well-established and avoidable environmental influence and a documented benefit of early detection.... We surveyed 61 CDKN2A/p16 mutation-tested adults from two kindreds about their attitudes toward genetic testing of minors immediately posttesting and 2 years later....Overall, 86.9% expressed support of melanoma genetic testing of minors, with the importance of risk awareness (77.4%) ...Concerns about inducing psychological distress or compromising children's decision autonomy were infrequently cited. Testing preferences did not vary by respondent age, gender, or melanoma history.  ... Respondents strongly supported melanoma genetic testing of minors, with most citing improved health behavior as a likely outcome. We discuss options for melanoma genetic counseling and testing of minors.

 CDKs are cyclin dependent kinases, and CDKN2A/p16(INK4a) is a cyclin dependent kinase inhibitor located on 9p21, and are employed in the cell cycle mechanism. We  have discussed these in our paper on  Backscatter and Melanoma. These are a specific set of genetic predispositions for early melanoma if a few other steps happen. Like excessive exposure to backscatter.

However the issue is not so simple. No matter what parents should monitor children's sun exposure. Also there is the genetic information, what would a parent do differently than what they should already do. No matter what, sun exposure, prohibition of tanning, and the like is an imperative. That is true almost no matter what. One should remember that Bob Marley died of melanoma. Thus a priori there is no protection.

Does the knowledge by the child of the genetic marker pose a sever psychological burden? Perhaps, the old tale is that almost every first and second year Med student comes down with Ebola or something like it, at least in their mind. There is a point when information has value and a point when it is merely a burden.

Testing has costs. Are the costs worth it? In this case most likely not. Reasonable behavior is warranted whether the genetic marker is present or not. So why test? Is it something that the parents want, another thing to speak of with other parents? This is clinically and scientifically interesting but it does not change behavior or outcomes, so why do it?