To the Editor: Meissen et al. (March 3 issue)1 reported results of their ongoing program of predictive testing for Huntington's disease. Nearly one third of the candidates (5 of 16) had an uninformative result. With the use of a single DNA probe (D4S10), it was impossible to determine which form of the DNA marker segregated with the gene for Huntington's disease in these families. Seventy persons at risk for Huntington's disease are participating in an ongoing predictive testing program at the University of British Columbia.2 Informativeness has been determined for 41 of these candidates with use of three linked DNA. © 1988, Massachusetts Medical Society. All rights reserved.