Presymptomatic, prenatal, and exclusion testing for Huntington disease using seven closely linked DNA markers.

Presymptomatic, testing, prenatal diagnosis, or exclusion testing are now available for persons at risk for Huntington disease. These tests will reduce uncertainty, assist in life planning, and prevent the birth of potentially affected children. We present the results of presymptomatic tests for 37 applicants including two prenatal and one exclusion test in 23 families. We initially used the markers G8, H5.52, F5.53, and pTV20 (D4S10), p8 (D4S62), and pRB1.6 (D4S81) and extended the informativity of the test at a later stage with the markers pKP1.65, C4H, S1.5 (D4S43), 674 (D4S95), 157.9 (D4S111), and YNZ32 (D4S125). Applicants with an unsuitable family structure were not admitted to the test. Of the 37 applicants, 33 were informative. In our hands the most efficient strategy is first to use the markers H5.52 (D4S10), pRB1.6 (D4S81), 674 (D4S95), pKP1.65 (D4S43), 157.9 (D4S111), YNZ32 (D4S125), and 252.3 (D4S115). The overall informativity in our data set was 84% and in the most recent test we achieved a 90-95% informativity. The other markers are used only when the first set is not informative.