In sheep, resistance to the CWD related TSE, scrapies, is dependent on genotype - the US tests for RR, QR, QQ in conjunction with codon 171. Per

http://www.wisconsinmedicalsociety.org/_WMS/publications/wmj/issues/wmj_v101n8/Cross.pdf

similar studies are being conducted on the elk population although, as of 2002, they state no in depth studies have been conducted on the white-tail deer population. They also suggest that when the genotype most resistant to CWD is identified, a breeding program similarly used by sheep producers may be implemented.