by your standards the gray gene doesn't exist they don't have a test for it either and if you read the mau abstract there does seem to be evidence for the gene they've narrowed down the probable location of the gene what is not known is if it has linkage to sabino and sabino may be caused by a number of different genes of which only sb has been mapped so far it is not known whether dominant white w and sabino spotting s share a common genetic background in this study a pedigree consisting of horses segregating for dominant white w was used to genetically localize the horse w locus microsatellite asb was found linked to w which allowed us to map dominant white to a region on horse chromosome q so i'd say it is overkill to call w an unproven theory especially when most of the dispute isn't among experts so much as among breeders who are not geneticists pearl and silver dapple i have no problem with someone adding pearl to the chart if there isn't a wikipedia article on it maybe that needs to be done too there is an article on silver dapple but i don't think data is in the chart yet here i also am ok with creating some consistency with the gene symbols but i haven't the time to do it someone else sure can best not to start a nomenclature fight whatever is the majority view probably best maybe a paragraph explaining other terminology would help