Clin Genet 2014: 85: 78 – 86 Printed in Singapore. All rights reserved  2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd CLINICAL GENETICS doi: 10.1111/cge.12090 Original Article Prenatal testing for Huntington’s disease in the Netherlands from 1998 to 2008 van Rij MC, de Koning Gans PAM, Aalfs CM, Elting M, Ippel PF, Maat-Kievit JA, Vermeer S, Verschuuren- Bemelmans CC, van Belzen MJ, Belfroid RDM, Losekoot M, Geraedts JPM, Roos RAC, Tibben A, de Die-Smulders CEM, Bijlsma EK. Prenatal testing for Huntington’s disease in the Netherlands from 1998 to 2008. Clin Genet 2014: 85: 78–86.  John Wiley & Sons A/S. Published by John Wiley & Sons Ltd, 2013 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. Conflict of interest None of the authors reported a conflict of interest. MC van Rij a,b , PAM de Koning Gans c , CM Aalfs d , M Elting e , PF Ippel f , JA Maat-Kievit g , S Vermeer h , CC Verschuuren- Bemelmans i , MJ van Belzen c , RDM Belfroid c , M Losekoot c , JPM Geraedts b , RAC Roos a , A Tibben c , CEM de Die-Smulders b and EK Bijlsma c a Department of Neurology, Leiden University Medical Centre, Leiden, the Netherlands, b Department of Clinical Genetics, Maastricht University Medical Centre, Maastricht, the Netherlands, c Centre for Human and Clinical Genetics, Leiden University Medical Centre, Leiden, the Netherlands, d Department of Clinical Genetics, Amsterdam Medical Centre, Amsterdam, the Netherlands, e Department of Clinical Genetics, VU Medical Centre, Amsterdam, the Netherlands, f Department of Medical Genetics, University Medical Centre Utrecht, Utrecht, the Netherlands, g Department of Clinical Genetics, Erasmus Medical Centre, Rotterdam, the Netherlands, h Department of Clinical Genetics, Radboud University Medical Centre, Nijmegen, the Netherlands, and i Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, the Netherlands Key words: continued pregnancy – exclusion test – exclusion-definitive test – grey test result – Huntington’s disease – intermediate allele – non-disclosure – PD – prenatal diagnosis – reproductive decision making – uptake Corresponding author: Dr Emilia K Bijlsma, Clinical Geneticist, Department of Clinical Genetics, University Medical Centre, 2300 RC Leiden, the Netherlands. Tel.: +31 0 71 5268033; fax: +31 0 71 5266749; e-mail: e.k.bijlsma@lumc.nl [PO BOX 9600] 78