I am not sure if these are genetic disorders but this may be worth investigating - how about grey horse melenoma? Also how about Cushings syndrome and insulin resistance. Alot of hoof disorders tend to run genetic, such as low angled, contraction of heels, club feet, base narrow, and base wide and so forth. And lets not forget a huge genetic disorder -HYPP positive horses in the AQHA, you should be able to look up alot on that topic.
