Skip to main content
Premium Trial:

Request an Annual Quote

Incidental Findings


Only a few years ago, physicians had to rely on pediatric patients' families to disclose whether children were the result of a consanguineous relationship. Having parents who are closely related is known to cause intellectual or developmental disabilities and congenital anomalies in offspring. Now, an array-based genetic test that clinicians routinely perform on children presenting with these symptoms negates the need for such confessions by showing spans of homozygosity that clearly indicate incestuous parental relationships.

"We didn't have any way to detect it if they didn't give us any information about it, historically," says Arthur Beaudet, professor of molecular and human genetics at Baylor College of Medicine. "But now we have a test that we do commonly on patients that makes it quickly evident if a child is the product of a very close relationship, like father-daughter, mother-son, brother-sister."

In The Lancet in February, Beaudet and his colleagues at Baylor reported their discovery of unexpected relationships between pediatric patients' parents, including cases in which they identified regions — some that span as much as a quarter of the genome — where heterozygosity was completely absent, indicating that the child was conceived by close relatives.

The clinical identification of incestuous relationships "is a relatively complicated matter, depending on the family circumstances," Beaudet says. For example, if the mother of a pediatric patient was younger than 18 — which is generally accepted as the minimum age for sexual consent in the US — at the time of conception, he says that physicians must consider the possibility of child abuse, and are therefore legally obligated to report it to the authorities.

Complicated circumstances

While child abuse is the most common scenario in which consanguineous conceptions occur, it's certainly not the only one. "There could be a variety of circumstances as to whether something was consensual or it was rape, so there are a number of legal and social questions, and one wants to handle things in such a way that [they] don't add to the harm that may already exist in a situation," Beaudet says.

Recently, he and his colleagues encountered a case in which a married mother of three children with cognitive and developmental disabilities — the eldest of which she conceived in a previous union — opted to submit their genetic samples for screening. The researchers discovered a span of homozygosity that indicated the oldest child was the product of an incestuous conception between first-degree relatives. When they informed the mother of what they found, Beaudet says she vehemently denied such a relationship and demanded that the test be repeated. "The test was repeated and [the result] was the same," he says. "And then she sort of broke down and said: 'My husband will divorce me if he finds out about this.' … There are just a lot of difficult things that come up."

That different countries — and indeed, US states — have different laws related to both sexual consent and abuse further complicates the problem from a legal standpoint. For Beaudet and other clinicians at Baylor — who perform SNP arrays on samples shipped to their labs from out of state in addition to the patient samples they process from children's hospitals in the Houston area — the mix of responses they get from physicians to genetic indications of incest has shown them the importance of ethics committees and establishing standard practices. While Beaudet says that the general consensus among physicians is to involve the appropriate authorities in suspected cases of incestuous conceptions involving minors, Beaudet adds that, in the end, individual clinicians must make their own "decision as to how they want to handle it locally." When he and others at Baylor have identified incestuous parental relationships in patient samples from other clinics, they've consulted with the physicians involved in order to share information and advice derived from their own experiences with this sensitive situation, Beaudet says.


Contextual considerations

There is, however, no standard way for researchers to deal with incidental findings, including those of incest. After finding a lack of consensus among researchers as to how best to deal with unexpected results, the University of Minnesota's Susan Wolf and her colleagues recommended in a 2008 Journal of Law, Medicine & Ethics article that investigators and institutional review boards distinguish incidental findings that they must report to research participants from those that do not necessitate disclosure, and that they develop protocols to address incidental findings from the point of initial consent to post-study communication.

Similarly, Baylor's Beaudet and his colleagues suggest in their Lancet article "that institutions establish a committee to discuss these and other ... issues with the purpose of drafting practice guidelines that deal with issues of consent, result disclosure, and reporting" in the clinical context, based on the possibilities for "harm in the form of stigmatization, emotional distress, and criminal accusations." In addition, they suggest that existing ethics committees at professional associations, such as the American College of Medical Genetics or the European Society of Human Genetics, also develop guidelines to assist clinicians who encounter this issue.

Yann Joly, a lawyer and assistant professor of genetics at McGill University in Montreal, says that physicians rely on those professional codes of ethical conduct as well as medical guidelines and applicable laws in their jurisdictions to guide their decision--making when faced with sensitive situations. While physicians "have a duty to inform their patients — and the parents of a minor child — of medically relevant findings," Joly says, "in some countries … the notion of therapeutic privilege — [the] right to withhold medical information for the benefit of one's patient — is extremely important."

Because the ethical and social ramifications of reporting suspected incest can vary across countries' borders as much as the legalities do, Joly says it would be "extremely challenging to develop international guidelines," though he adds that national guidelines would likely be easier to establish and could prove beneficial.

However, Joly is unconvinced that new protocols are necessary at the institutional level, as "most hospitals have clinical ethical committees or similar structures already in place that can support physicians having to [make] difficult clinical decisions." He adds, "I am not sure about the need to create a specific new type of committee that would be dealing exclusively with communicating … potentially incestuous relationships."

Harvard Medical School's Isaac Kohane says that as increasingly sensitive situations emerge, institutions will be forced to evolve. "Most institutions are struggling to keep up with current regulatory requirements, so it will require a re-thinking of institutional commitments," he says.

But with the issue of incest identification out on the proverbial table, McGill's Joly says physicians are increasingly aware of the possibility of other unintended consequences of clinical genetics. Just as the Wolf et al. guidelines "need to be revisited [and] improved over time," clinical geneticists must adapt a flexible framework with which to address ethically sensitive situations as advancing technologies rapidly unmask them.

Going forward, Baylor's Beaudet says that social workers, too, must adapt their thinking to accommodate genetic testing results. "Typically, social workers go out to the home [in question] and visit with the various family members," he says, "and make some assessment of whether ... an infant is at risk," he says. In cases that involve genetically identified incest, however, social workers now face questions of "whether maybe the mother of an infant is at risk, and is the home environment appropriate for both the mother and the infant," Beaudet adds.

The Scan

Ancient Greek Army Ancestry Highlights Mercenary Role in Historical Migrations

By profiling genomic patterns in 5th century samples from in and around Himera, researchers saw diverse ancestry in Greek army representatives in the region, as they report in PNAS.

Estonian Biobank Team Digs into Results Return Strategies, Experiences

Researchers in the European Journal of Human Genetics outline a procedure developed for individual return of results for the population biobank, along with participant experiences conveyed in survey data.

Rare Recessive Disease Insights Found in Individual Genomes

Researchers predict in Genome Medicine cross-population deletions and autosomal recessive disease impacts by analyzing recurrent nonallelic homologous recombination-related deletions.

Genetic Tests Lead to Potential Prognostic Variants in Dutch Children With Dilated Cardiomyopathy

Researchers in Circulation: Genomic and Precision Medicine found that the presence of pathogenic or likely pathogenic variants was linked to increased risk of death and poorer outcomes in children with pediatric dilated cardiomyopathy.