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Routine genetic tests in children can suggest that they were the products of incest, putting clinicians in an ethically awkward situation, researchers suggested.
The genetic tests that have revolutionized the identification and treatment of many illnesses can also unearth family secrets like incest, sparking an ethical discussion in the medical community over how these inadvertent findings should be handled.
At Baylor College of Medicine in Houston, sophisticated DNA analyses used to diagnose such disabilities as birth defects, epilepsy or developmental delays revealed that in some children, about 25 percent of genetic material inherited from their mother was the same as material inherited from their father.
That suggested their parents were first-degree relatives -- father and daughter, brother and sister, or mother and son. Children who inherited half as much identical DNA from both parents likely were the offspring of second-degree relatives, such as an uncle and niece. Had the mothers and fathers of these youngsters been unrelated, those same stretches of DNA would have differed.
In the few months that Baylor has been performing these detailed genetic tests, there have been fewer than 10 cases of consanguinity -- the phenomenon of inheriting the same gene variations from two closely related people, said Dr. Arthur L. Beaudet, chairman of Baylor's department of molecular and human genetics. However, wider use of such testing in children with disabilities is expected to identify additional cases of incestuous parentage.
If the child's mother is a minor, a physician may be legally obliged to report his or her suspicions to local child protection agencies and/or the police, according to Arthur L. Beaudet, MD, and colleagues at Baylor College of Medicine in Houston.
Writing in the Feb. 12 issue of The Lancet, Beaudet and colleagues said they had come across several such cases themselves in the course of performing genomic tests on children with various conditions, using single nucleotide polymorphism (SNP) arrays.
"SNP-array analysis revealed large regions of absence of heterozygosity on multiple chromosomes," they wrote. "In some case, these regions accounted for about a quarter of the genome -- a finding most consistent with the child having been conceived by first-degree relatives" such as a father-daughter or sister-brother parental pairing.
As SNP arrays become more common in clinical practice, more such cases are likely to come to light, the Baylor group predicted.
Beaudet and colleagues pointed out that when the mother is a minor, an incestuous relationship could reflect rape or other forms of sexual abuse, which would make the situation a police matter.
"The physician's duty to report is less clear in cases where the mother is an adult and might depend on whether she was a minor or an adult at the time she became pregnant," the group noted.
Such possibilities also create concerns about informed consent prior to conducting the genomic tests. Up to this point, probably very few clinicians have discussed the possibility that testing could reveal incestuous parentage, which in turn could lead to very real problems for the parents and children involved.