In the Nov. 15, 1996 issue of SCIENCE, Polymeropoulos et al.
have mapped the gene for Parkinson's disease to chromosome 4.
In particular, "between markers D4S2361 and D4S421 at a
recombination distance of 0.00 cM from marker D4S1647".
I have only been able to locate marker D4S421. The other
two don't seem to exist anywhere. I've tried Unigene,
Genethon, and most of the other mapping sites on the web
(like Sanger, Whitehead/MIT, Wellcome Trust -- even though
they're not necessarily involved with Chromosome 4).
Could somebody explain why all markers would not be available,
some false assumptions I've made in expecting to find them,
or point to a site that I can locate them?