Clinical and counselling implications of preimplantation genetic diagnosis for Huntington's disease in the UK

Abstract

Huntington's disease is an autosomal dominant neurodegenerative disorder that usually occurs in adult life. Individuals at risk can have a gene test before the onset of symptoms, and prenatal diagnosis is available. Preimplantation genetic diagnosis (PGD) for Huntington's disease is now available for couples in whom one partner has the gene for Huntington's disease. A licence to practise PGD is required from the Human Fertilisation and Embryology Authority, and there are several complex issues relating to PGD for Huntington's disease that require consideration. The partner of the Huntington's disease gene carrier should have a presymptomatic test to ensure accuracy in a PGD cycle. There should be a delay between blood sampling and testing for Huntington's disease to allow time for reflection and withdrawal from testing. All PGD treatment has an associated risk of misdiagnosis. If confirmatory prenatal testing is not undertaken after a successful PGD cycle, no confirmation of diagnosis will be obtained at birth. Guidelines indicate that individuals who are at risk cannot be tested before 18 years. There is concern over the ability of a child or adolescent to make an informed choice about testing before this age. Confirmatory testing at birth after PGD would be in direct contravention of these guidelines. In the UK, the law requires consideration of the welfare of children born after assisted conception treatment. Presenting symptoms of Huntington's disease may affect the parenting abilities of an affected individual. There is a need for an assessment of a patient's current Huntington's disease status and their planned provision of care of children if Huntington's disease affects parenting. It has been necessary to create a detailed working protocol for the management of PGD for Huntington's disease to address these issues.