Predictive DNA-testing for Huntington's disease and reproductive decision making: a European collaborative study

This European collaborative study addresses the question whether a
predictive test result for Huntington's disese (HD) has an effect on
subsequent reproduction by comparing carriers and non-carriers of the
Huntington mutation. A unique characteristic of this study is that this
evaluation is done in persons at reproductive age who had a predictive test
after the identification of the Huntington gene and who were counselled in
one of the participating centres. Data were collected for 180 carriers and
271 non-carriers who received a predictive test result in the period
1993-1998 in Aberdeen, Athens, Cardiff, Leiden, Leuven, Paris or Rome. The
mean age of the total study group was 31.5 years and for about half of the
group the follow-up interval was 3 years or more, with a maximum of 7
years. The collaborative study clearly revealed an overall impact of the
predictive test result on subsequent reproduction: 14% of the carriers had
one or more subsequent pregnancies vs 28% of the non-carriers. In the total
carrier group a prenatal test was carried out in about two thirds of the
pregnancies and one child was born after preimplantation genetic diagnosis;
artificial insemination by donor, egg cell donation or adoption were not
reported. A more refined analysis was performed in the subgroup with a
follow-up interval of at least 3 years and who reported "family planning"
as a motive to apply for predictive testing in the pretest period. The
complexity of this motive is discussed. In this subgroup with a desire for
children in the pretest period the effect of the predictive test result was
more pronounced: 69% of the non-carriers had subsequent pregnancies while
only 39% of the carriers who mentioned "family planning" as one of the
major reasons to apply for predictive testing had a subsequent pregnancy.
Of the carriers with one or more subsequent pregnancies the percentage
using prenatal diagnosi was slightly higher than the percentage not using
it, although there were clear differences from one centre to another. The
latter group's decisions may seem more intriguing but may be partially
understood based on stage theories of health behaviour. Last, but not
least, whatever option is chosen by a couple at increased risk of
transmitting the Huntington mutation, it is of the utmost importance that
professionals fully respect this decision and support the couple.