Amniocentesis,a prenatal testing method where fluid is drawn for analysis from the amniotic sac surrounding the fetus, usually at 16-18 weeks of gestation, [6] p3
Chorionic villus sampling (CVS), a prenatal testing method involving taking a sample of cells for analysis from the finger-like edges of the fetal part of the placenta, usually at 9-11 weeks of gestation. [2]
Linkage analysis, a method of DNA testing used when a direct test is not available. This was the only testing available for VHL before the gene was found in 1993. A study is made of the inheritance pattern of the set of genes on chromosome 3 that are usually inherited as a group. Based on analysis of these groupings, a prediction can be made whether this person is likely to have inherited the group with the altered VHL gene in it.