Bone Scans and DNA Testing by Major League Baseball

The New York Times published a very interesting piece a few days ago called Baseball's Use of DNA Raises Questions.

The impetus for these tests:

Dozens of Latin American prospects in recent years have been caught purporting to be younger than they actually were as a way to make themselves more enticing to major league teams.

Apparently, such players have been able to borrow the birth certificate of a younger child from some other family.

Can these tests actually reveal one's age? In the case of DNA, no. However, it can be used to check whether a given player is actually related to the parents listed on the birth certificate. According to the Times, this alone was enough to void the signing of a Yankee prospect last year from the Dominican Republic.

In the case of a bone "scan", I presume the Times actually means a bone age study, in which an X-ray of a subject's hand and wrist (and sometimes other body parts) is compared to a standardized atlas of age-matched X-rays for various ages. How reliable is a bone age study? Not very.

I interpret these occasionally in my practice. When I give my estimate of someone's skeletal age, it is accompanied with considerable variation -- usually one standard deviation equals about a year. In the specific case of a boy with a chronological age of exactly 16 years (192 months), the mean of the expected skeletal age is 195.3 months, where one standard deviation = 12.9 months. From these figures, we can calculate that 95 % of 16 year old boys should have a skeletal age varying between 169.2 and 220.8 months, i.e. 14.1 and 18.4 years old. This 95 % confidence interval of 4.3 years makes a bone age study pretty darned unreliable.

While bone age studies may be of dubious value, they don't lead to a lot of ethical dilemmas. DNA testing, on the other hand, does.

So far, MLB only seems to be using DNA testing to help verify a player's age. However, it's not hard to imagine how they might use other genetic information as well.

Mark Rothstein, a professor of bioethics at the University of Louisville School of Medicine, said: “The funny thing about this all is that the most famous baseball player with a genetic disorder was Lou Gehrig. Would they have signed him if they knew he was predisposed to A.L.S.?”