With the advent of new genetic tests that can pinpoint chromosome abnormalities with precision, nearly a quarter of children suffering from developmental disabilities are now diagnosed with a genetic condition. Knowing the genetic defect, doctors have a better idea how to tailor therapies to treat these children. Such genetic tests, first introduced to the clinic over the past decade, yield more information than previous approaches that relied on gross chromosomal structure alone. And in fact, some of these tests — called chromosomal microarrays (CMAs), which rely on uniquely identifying single nucleotide polymorphism (SNP) signatures — often produce much more information than clinical geneticists bargained for.
In an opinion piece published online yesterday in The Lancet, Arthur Beaudet of Baylor College of Medicine in Houston warns that these genetic tests often flag incidences of incestuous parentage, and physicians need to be prepared to deal with the fallout from learning about such taboo relationships. Beaudet corresponded with Nature Medicine via email about the impact of CMA on his own practice and the challenges that these tests introduce to clinical geneticists everywhere.
Why do you feel it is important to get the word out that incest could be detected by these genetic tests?
Encountering a lab result that tells you that a child is the product of an incestuous mating is a relatively new thing for doctors, and it raises some difficult issues of which clinicians should be aware. Probably the biggest question is whether the parents of every child who has an array test with SNPs should be specifically informed that the test detects incest. That is not happening now.
Do routine genetic tests often lead to the discovery of incest?
Fortunately, incest is relatively rare, but we do not know exactly how rare. We don’t know yet how frequently this will occur. But it has happened, and will continue to happen.
Do you see such genetic testing then as a double-edged sword?
I think that the benefits exceed the risks or harms, but minimizing the harms is what our letter [in The Lancet] is about. Sometimes the physician is given a history that a child is known to be the product of an incestuous mating. Other times the mother does not reveal that information. Many of these hidden cases involve sexual abuse of minors resulting from father–daughter, mother–son, or brother–sister relationships. The minor is often threatened with harm if she reveals the information. In general, I believe that the abused minors and society benefit by recognizing the abuse.
Should genetic tests become the go-to approach in suspected cases of incest?
Yes. In the past, if our suspicions [of incest] were high and the mother was a minor, we might ask a mother or grandmother about this possibility directly or ask child protective services to investigate for child abuse. Today, there is the option of performing a CMA test with SNPs to test whether incest is present or not.
What safeguards should be put in place when incest is discovered through genetic testing?
I would like to see teams, especially at children’s hospitals, with prior training and expertise in social services, legal matters, psychiatric support, and other issues ready to step in rare cases when undisclosed incest is discovered. There may be times when the team needs to be prepared to move minors or older juveniles to a safe house on an emergency basis.