Prenatal testing for Huntington's disease in the Netherlands from 1998 to 2008

This study aims to give an overview of the number of prenatal tests for Huntington's disease (HD), test results, and pregnancy outcomes in the Netherlands between 1998 and 2008 and to compare them with available data from the period 1987 to 1997. A total of 126 couples underwent prenatal diagnosis (PND) on 216 foetuses: 185 (86%) direct tests and 31 (14%) exclusion tests. In 9% of direct tests the risk for the foetus was 25%. Four at-risk parents (4%) carried intermediate alleles. Ninety-one foetuses had CAG expansions ≥36% or 50% risk haplotypes: 75 (82%) were terminated for HD, 12 (13%) were carried to term; four pregnancies were miscarried, terminated for other reasons or lost to follow-up. Unaffected pregnancies (122 foetuses) resulted in the birth of 112 children. The estimated uptake of PND was 22% of CAG expansion carriers (≥36 repeats) at reproductive age. PND was used by two new subgroups: carriers of intermediate alleles and 50% at-risk persons opting for a direct prenatal test of the foetus. A significant number of HD expansion or 50% risk pregnancies were continued. Speculations were made on causative factors contributing to these continuations. Further research on these couples' motives is needed.