Experience in prenatal testing for Huntington's disease in the Netherlands: Procedures, results and guidelines (1987-1997)

We have performed 31 exclusion tests (43 per cent) and 41 direct tests (57 per cent) in 43 couples at risk, in the period 1987 to 1997 in Leiden, The Netherlands. This resulted in termination of 28 pregnancies (39 per cent), with an increased risk. In 28 couples (65 per cent), the woman was at risk. Prenatal testing in consecutive pregnancies (mean number: 3) was performed in 15 couples (35 per cent), with a mean time interval of 15 months. Paren ts should make an independent choice for (every) pregnancy,although most (8 6 per cent) did not change their initial choice. It is important that the p osition of children in the same family, of whom some know their status as a result of prenatal testing, whereas others remain at risk, is taken into c onsideration in counselling. The relative number of exclusion tests when co mpared with direct tests has diminished since the mutation was identified. The prenatal exclusion-definitive test (Fig. 1) was rarely used (2/72, 3 pe r cent). Nowadays, direct mutation testing of the fetus only is simpler and faster and the risk of disclosure of the genetic status of the at-risk par ent is only 25 per cent. This test should therefore be offered as another o ption and included in the international guidelines. The uptake for prenatal testing is low: for 2 per cent of the at-risk persons, 11 per cent of the tested carriers and a small group of at-risk persons wishing not to be test ed themselves, prenatal testing seems an acceptable choice regarding reprod uction. Copyright (C) 1999 John Wiley & Sons, Ltd.