Huntington's Disease

Prenatal Testing

Predictive genetic testing before birth (prenatal testing) is associated with unique concerns. For example, direct mutational analysis that provides a positive result indicates that a parent also carries the mutation. However, in some cases, parents may wish to determine the risk of disease development in the developing fetus, yet may not wish to know their own risk. Although not all testing centers provide such tests, some conduct a form of indirect DNA analysis (restriction fragment length polymorphism or RFLP) in such cases. To perform this form of testing, fetal DNA samples are acquired by means of amniocentesis or chorionic villus sampling (CVS).

Testing may confirm whether the developing fetus inherited chromosome 4p from the affected grandparent on the side of the family with HD. If the disease gene was inherited from the affected grandparent, the results indicate that both the developing fetus and the parent have a 50% risk of developing the disease. Such testing is considered controversial and raises many ethical concerns. It is generally advised that at-risk individuals who are considering having children seek genetic counseling before pregnancy.