Houston doctors are reporting that the newest generation of DNA testing, now in wide use, is revealing many previously missed incest cases that raise difficult legal and ethical questions.
In a letter in the British medical journal The Lancet on Saturday, Baylor College of Medicine geneticists advise hospitals to begin grappling with the issues that arise from the testing, which unexpectedly can show a patient was conceived through so-called "first-degree" familial relationships -- father-daughter, mother-son or brother-sister.
"Hospitals that work with this sort of testing need to become more familiar with dealing with these kind of situations because they're going to be seeing them more often," Dr. Arthur Beaudet, Baylor's chairman of molecular and human genetics and one of the letter's authors, said in an interview. "We hope our letter will jump-start the process by which institutions put together guidelines."
Beaudet wrote in the letter that "clinicians uncovering a likely incestuous relationship may be legally required to report it to child protection services and, potentially, law enforcement officials" since the pregnancy might have occurred "in the setting of sexual abuse."
The letter was prompted by a Baylor laboratory's discoveries that developmental disorders in a number of pediatric patients were caused by incestuous relations not previously disclosed to doctors.
The testing is done to find the disorder's genetic basis, typically involving mutations, deletions or duplications. But large blocks of identical DNA are evidence the child's parentage involved first-degree relatives.
Children born to first-degree relatives have a developmental disability about half the time, said Beaudet.
Beaudet said the test is now being used by the nation's 20 to 30 largest medical centers. These centers and private labs routinely get blood samples shipped to them for testing.
Sex between first-degree relatives is illegal throughout the country, though it is a misdemeanor in Texas and rarely reported when both parties are adults.
Though doctors are required to report suspicions of child abuse, Beaudet said, their obligations are less clear when the mother is an adult and protected by doctor-patient confidentiality.
A committee of Baylor, Texas Children's Hospital and Ben Taub General Hospital representatives is almost finished crafting a policy about the issues raised. Chairwoman Amy McGuire, a bioethicist, said these issues include consent, results disclosure and reporting.
McGuire said she had not previously heard discussion of the issue among her counterparts, but she dismissed the idea the issues raised are new.
"Certainly, the concept of incest gets people a little on edge," said McGuire. "But we do a lot of diagnostic tests that have the potential to show possible evidence of child abuse, the most dramatic ethical issue raised by this testing's occasional discoveries of incest."