Predictive genetic testing in a young child: a case report

Abstract

The many different professional guidelines [1] that give advice about genetic testing in children have been extensively reviewed in other papers in this issue of the journal. Here we present a case report illustrating how the issue of genetic testing in children continues to present challenges to clinical teams in practice. The identifying details of the case have been altered to preserve the anonymity of the family involved. David was diagnosed with an attenuated form of Familial Adenomatous Polyposis (aFAP) [2, 3] in his mid 20s. His polyp load at the age of 25 was such that he had a prophylactic colectomy and ileorectal anastomosis. The pathogenic mutation which caused the condition had been identified in David and other members of his family and thus a predictive test for unaffected family members or future members would be technically straight forward. Such testing is important in determining who should and who should not receive regular screening for bowel polyps. After the initial diagnosis, David had moved elsewhere and had been followed up by other genetics and surgical services. Recently, David, and his wife Dawn, moved back to the area. The genetics department received a referral from a local GP to see David and Dawn to discuss predictive genetic testing in their baby daughter, Daisy. At the first clinic appointment the couple made it clear that they would like Daisy tested there and then, when she was 6 months old, as they thought that the sooner her genetic status was known, the better; and that a blood test now would be less traumatic for Daisy. David mentioned his diagnosis and its genetic confirmation during the first antenatal appointment and the midwife attending to Dawn therefore suggested that a genetic test was possible in the early stages of the pregnancy. There was a 50% chance that any child would be affected in the same way as David. Although the options of amniocentesis or chorionic villous sampling had been discussed with the couple, they declined such invasive antenatal testing, because they did not wish to increase the risk of a miscarriage and they would not consider terminating this pregnancy. Knowing that the risks of the test were minimised after birth, they thought they would delay testing until Daisy was a baby and therefore requested an appointment with genetics shortly after her birth. They also outlined other reasons for requesting the test at this stage during the genetics clinic appointment. Firstly, they believed it would help them in their future reproductive decision-making: the couple felt it was their duty to stop the faulty gene from being transmitted to future generations. If Daisy had not inherited the gene, then they would not have any further children as they would have succeeded in this aim. If Daisy had inherited the condition, then future children with the condition might be a bonus to the family as the affected children could support each other through the disease stages. The couple were already in their mid-thirties and therefore did not wish to delay further family planning for too many years. A second reason for requesting the test now is that the couple believed they could get Daisy used to hospitals from an early age if she had inherited the condition. She could attend outpatient appointments with David, they argued, and become familiar with what would happen to her in the future. If she were unaffected this would not be necessary. Thirdly, David described his familial polyposis as a condition that ‘belonged’ to his family and a condition that G. Crawford (&) A. Lucassen Wessex Clinical Genetics Service and Cancer Sciences Division, University of Southampton, Level G, Princess Anne Hospital, Coxford Road, Southampton SO16 5YA, UK e-mail: gc@soton.ac.uk