Thursday, May 19, 2011

Genetic guilt and disease susceptibility testing in kids

When my son developed symptoms of asthma at age three, I found it hard to understand why my wife, who also has asthma, expressed a profound sense of responsibility for his illness. Of course, a large component of asthma is inherited, but who was to say that my son's condition wasn't as much or more the result of being raised in a city, or other exposures that we couldn't anticipate or control? (It certainly wasn't from cigarette smoke, which has always been banned in our household.) But a year later, when relatives and teachers began noticing that one of my son's eyes would occasionally slip out of focus, I felt the first twinge of guilt. That sensation only increased after we took him to an ophthalmologist and confirmed his diagnosis of strabismus (the technical term for "lazy eye"). It was the very same condition whose correction had required two eye surgeries when I was eight and twelve years old. And alas, as I suspected, the medical literature indicates that strabismus is inherited, too.

Many parents of young children are fortunate enough not to have any outward signs of inheritable disorders to pass on to their offspring. Common chronic conditions such as diabetes, coronary artery disease, and cancer often don't manifest themselves until middle age or later, by which time the children have become adults themselves. However, genetic testing for these types of conditions is now being marketed directly to consumers, and parents might theoretically order these tests for their children to give both a better idea of what health problems may lie ahead.

The journal Pediatrics recently published an analysis of an online survey of 219 parents enrolled in a separate study of the effect of genomic health risk profiles on health-related behaviors (which I described in a previous blog post). Overall, parents expressed moderate interest in obtaining genetic testing for their children, with the most interested parents being those who would choose testing for themselves; placed a high value on genetic knowledge for its own sake; anticipated feeling good if their children were found to have reassuringly low chronic disease risks; and felt capable of modifying their child's lifestyle if needed.

Putting aside for a moment the limitations of this particular study, which may not be representative of the attitudes of the general population toward genetic tests, it's interesting to consider the larger question of what we gain or lose by predicting our medical futures, and those of our children, with very imperfect tools. It's one thing to detect early signs of incurable diseases, such as Alzheimer's dementia (personally, I'll pass), but learning that one has a higher risk of a future preventable "lifestyle" disease might potentially motivate that person (or his parents) to pay more attention to diet, physical activity, or other behaviors to counteract that risk. I write "potentially" because as far as I know, no one has even come close to proving that the possession of genetic knowledge is self-motivating, rather than self-defeating. (If I'm destined to develop diabetes anyway, why not have that extra slice of cheesecake now?)

Perhaps there will be a day when a detailed map of one's genome will have at least as much predictive value as I.Q., or SAT or MCAT scores - some, but not a great deal. Until then, I will continue to restrict screen time, send my kids outside to play, feed them lots of whole grains, fruits and vegetables, and cross bridges of future health episodes when we come to them.

1 comment:

  1. Right on Dr Lin. After your post on Overdiagnosis I read the book, and have rethought a great deal on early diagnosis and in this case genomic testing. I've always been skeptical, but now feel it is just a really bad idea. I agree with you, live the best way you can and deal with issues as they present themselves. Don't go looking for trouble.

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