Allelic frequencies of RFLPs at loci closely linked to the HD gene, D4S95, D4S91, D4S141, and D4S90, were determined in 13 Huntington's disease (HD) patients from nine Chinese families and 129 normal subjects.
To explain these results, it was suggested that the HD locus (HD) lies close to the telomere and that a recombination event took place between HD and the most telomeric marker examined, D4S90.
Twelve Italian families with Huntington disease were tested with 10 probes known to be linked to the disease locus and able to detect polymorphisms at the following loci on chromosome 4: D4S10, D4S127, D4S95, D4S43, D4S115, D4S111, D4S90.
D4S95 is a most useful DNA marker for predictive testing programs, while D4S90 will serve as a useful starting point for identifying DNA fragments closer to the gene for HD.
These data suggest that it may be possible to construct high and low risk haplotypes, which may be helpful in DNA analysis and genetic counselling for HD, and represent independent evidence that the gene for HD is centromeric to more distally located DNA markers such as D4S90.