Analyzing children’s DNA to diagnose developmental disabilities and congenital anomalies can inadvertently reveal that some were conceived through incest, raising ethical, social and legal issues that the institutions and scientists involved must deal with, said US researchers in a report published in The Lancet this week.

The report highlights a need to address a problem that is likely to grow as DNA analysis technology becomes more accessible and affordable as a diagnostic tool: what should doctors do if they suspect that the child they are treating was born through incest?

This scenario is fraught with ethical, legal and social implications, for all concerned, and the authors of this report, who are themselves facing these issues, call for new guidelines to help doctors decide how to act.

Disabilities arising from missing or duplicate genes are known to occur more frequently in children born through incest.

Children who are not born through incest normally have a genome (that is the map of their whole DNA) with a high degree of “heterozygosity”, reflecting the fact they received half their genes from a mother who was biologically unrelated to the father, from whom they received the other half.

Because of developments in genome technology, and because that technology is now more affordable, doctors are now increasingly able to scan the genomes of individual children to look for missing or duplicate sequences of DNA code, called single nucleotide polymorphisms (SNPs or “snips”), that might explain a disability. The tests they use are called SNP-based arrays.

In children born from incest, their genomes show an “absence of heterozygosity”, reflecting the fact that their DNA contains large chunks where the mother’s and father’s contribution are identical, because they themselves shared much of their genetic code. The more chunks of the child’s DNA that show the mother’s and father’s contribution are identical, the more likely it is that they are first degree relatives, such as father and daughter, mother and son, or brother and sister.

Senior author Dr. Arthur Beaudet, chair of molecular and human genetics at Baylor College of Medicine in Houston, Texas, and colleagues wrote that in their practice they have identified several children referred for developmental disabilities and congenital anomalies in whom large blocks of their DNA showed an “absence of heterozygosity on multiple chromosomes”, and in some cases this accounted for about a quarter of the genome, suggesting the children were the offspring of first-degree relatives.

“We have discussed these issues with legal and ethics experts at Baylor and Texas Children’s Hospital, and we are considering how best to handle them,” said Beaudet in a statement.

In most states of the US, the law requires doctors to report any suspicions of child abuse, and if they suspect that a pregnancy is the result of abuse, then they have to report it to child protective services, and potentially, to the police.

However, Beaudet said the doctor’s responsibility is less clear when the mother is an adult. For instance, it might depend on how old she was and what the family situation was, when she conceived.

Revealing that a child may have been conceived through incest raises thorny social problems too.

The mother may deny that incest took place; she may be frightened and feel she and her child would be unsafe if this came out.

Beaudet and colleagues suggest this is an issue that demands new practice guidelines on consent, disclosure of results and reporting.

They urged health care institutions and professional societies such as the American College of Medical Genetics, the American Society of Human Genetics, and the European Society of Human Genetics, to either set up or task existing committees to tackle the ethical, legal and social implications of identifying potential incestual relationships as a result of this kind of analysis.

“Identification of incestuous parental relationships by SNP-based DNA microarrays.”
CP Schaaf, DA Scott, J Wiszniewska, AL Beaudet
The Lancet, Vol. 377 No. 9765 pp 555-556, published online 12 February 2011.

Additional source: Baylor College of Medicine (10 Feb 2011).

Written by: Catharine Paddock, PhD