Houston doctors find dilemma in tests showing incest DNA testing gives doctors a new dilemma

Baylor geneticists warn procedure can detect incest, raise ethical issues

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 today, Baylor College of Medicine geneticists advise hospitals to begin grappling with the issues that arise from the testing, which can unexpectedly 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.

Legal concerns

Children born to first-degree relatives have a developmental disability about half the time, said Beaudet.

Baylor began using the new test about six months ago. During that time, Beaudet said, the lab has seen evidence of incest fewer than 10 times.

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, he said.

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.

Reactions to letter

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."

William Winslade, a University of Texas Medical Branch at Galveston ethicist, applauded Baylor's letter, saying it's important for institutions to set guidelines about how much disclosure is necessary for tests that have such serious legal, ethical and psychological consequences.

Winslade said he's "inclined to think that more rather than less disclosure is appropriate."

Tests showing 25 percent of identical DNA are evidence of parentage by first-degree relatives. The percentage drops to 12.5 percent for uncle-niece relationships and about 6 percent for first cousins.

Beaudet said he is not interested in judging the latter two cases, which are not taboo in some societies.

Beaudet says he expects the letter will be criticized for making public what researchers in the field knew was occurring before they had the evidence to prove it. He said institutions should utilize "what this new technology is bringing into the open."

"I've been in this field for 40 years so this is no surprise to me," said Beaudet. "But it is an opportunity to open people's eyes to what goes on and discourage the problem."

todd.ackerman@chron.com