Close genetic linkage has been shown between the DNA sequence G8 (locus D4S10) and 16 British families with Huntington disease using the HindIII, EcoR1, Nci1, and Pst1 polymorphisms detected by G8, and by combining all the polymorphisms to give a combined haplotype. Two recombinants have been detected in these families giving a maximum lod score of 17.60 at a theta of 0.02. These results confirm the originally reported linkage between the loci and provide evidence against significant multilocus heterogeneity for Huntington disease.