Microarray results as an indicator of sexual abuse

Abstract

This case report illustrates the unexpected identification of intrafamilial sexual abuse of a young mother through genetic testing of her child. The child’s genome was found to have a relatively common chromosomal condition with congruent clinical manifestations, but the microarray also suggested a close biological relationship between the parents because of a high degree of homozygosity. This prompted a child protection investigation as the mother had been a minor at the time of conception, and intrafamilial sexual abuse was confirmed. Both the intended and unintended results of microarray should be considered with respect to the health and social context of the child and their biological parents. This becomes particularly important for young mothers and raises protection concerns when significant amounts of homozygosity (consanguinity) are detected.

Genetic testing using single-nucleotide polymorphism (SNP) chromosomal microarray is commonly performed in individuals with congenital anomalies, intellectual disability, dysmorphisms, and/or developmental delays. This testing allows for the identification of copy number variations in a patient’s genome. SNP microarrays can also identify areas of homozygosity (1). Although not done for this purpose, the degree of homozygosity can provide information regarding how closely the parents are related (i.e., level of consanguinity) (2).

Sexual abuse is common in the Canadian population with 14.4% of women and 5.8% of men reporting that they experienced this form of abuse before the age of 16 years (3). However, most cases remain unreported to authorities, including health professionals, and it remains a topic that is hidden in many people’s lives.

In this report, we describe a case in which genetic testing of a child led to the identification of intrafamilial sexual abuse of his mother.

CASE PRESENTATION

An 18-month-old boy was referred to a community paediatrician after his family physician noted an unusual facial appearance. The child and his 16-year-old mother attended the appointment. Further history included that this child was born to a 14-year-old mother and a 14-year-old father with distinctly different ethnic backgrounds. The pregnancy, delivery, and infancy period were healthy. Undescended testes and recurrent wheezing were previously noted by the family physician. The paediatrician identified trigonocephaly, mild hypotonia, and mild delays in motor and language skills. She initiated testing which included a microarray. The microarray subsequently identified Klinefelter syndrome, and referrals for supportive services were made, including to a medical genetics specialist.

During review of the microarray results, the geneticist noted long stretches of homozygosity on the report. As a result, a request was made to the laboratory to provide further information. The laboratory estimated that the level of homozygosity suggested that the parents were likely to be first- or second-degree relatives. On reflection, the geneticist recognized that the mother was a minor at the time of conception and that her teenage boyfriend was most likely not the father of her child. She consulted with the hospital child maltreatment paediatrician and a report was made to the local child welfare agency for suspicion of intrafamilial sexual abuse. This suspicion was confirmed by the child welfare agency in cooperation with law enforcement, and the case proceeded through the criminal justice system. Support was provided to the mother during this process.

CASE DESCRIPTION

Cases involving intrafamilial sexual abuse of a teenage minor uncovered through patient genetic testing have rarely been reported in the literature (4). When conducting genetic testing, it is not unusual to find single or multiple long areas of homozygosity in a patient’s genome. However, once the percentage of homozygosity reaches a certain level, it is likely that the parents are first- or second-degree relatives (5). In certain circumstances, the degree of relationship between the parents can be overestimated, and therefore, careful consideration of the family history and interpretation of results by a clinical geneticist is required. In general, research suggests that a close parental relationship exists when the child’s genome consists of more than 10% of areas of homozygosity each measuring 2 to 5 Mb or larger (5); for a first-degree familial relationship, the expected size of all areas of homozygosity in the genome is 720 Mb (540 ~ 1,080), while for a second-degree familial relationship, the expected size of all areas of homozygosity in the genome is 360 Mb (270 ~ 539) (6,7).

The Canadian College of Medical Genetics (CCMG) recommends that all laboratories performing microarray should have a policy in place for reporting regions of absence of heterogeneity (AOH) (8). The CCMG has also issued clinical guidance in collaboration with the Society of Obstetricians and Gynecologists (SOGC) for prenatal testing (9). These guidelines recommend that the referring physician should be informed of the possibility of consanguinity as indicated by genomic areas with AOH and that this consultation should occur before the laboratory includes these results in the report (9). It is then the responsibility of the ordering clinician to consider whether sexual abuse could be possible in the case. Best practice standards for pre- and postnatal counselling, and support of the parent and child should be maintained.

In the Canadian context, physicians have a duty to report any reasonable concern for the possibility of sexual abuse (or other forms of child maltreatment) to the local child welfare agency (1,2,4–6,10). In complex situations such as the one described by this case, consulting with specialists, such as a medical geneticist and a paediatrician with expertise in child maltreatment paediatrics may be helpful.

CONCLUSION

This case illustrates the importance of considering both the intended and unintended results of genetic testing and working with the laboratory to obtain additional information when necessary. If larger than normal areas of homozygosity are found in a patient’s genome, suggesting first- or second-degree parental relationship, physicians should consider both the health and social implications of this information, including whether it raises concerns for sexual abuse of a young mother.

Funding information: There are no funders to report for this submission.

Potential Conflicts of Interest: All authors: No reported conflicts of interest. MGKW testifies in court as an expert witness in cases of child maltreatment. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.