This is especially exemplified by our examination of SLC3A1 and SLC7A9 variants in cystinuria, where we cannot exclude the possibility that the studied missense variants represent modifiers or linked markers predictive of disease risk on some breed backgrounds such as Bulldog ancestry due to undiagnosed signs of cystinuria in the EMRs, gender-specific differences in manifestation, or later onset of disease. The gene discussed is SLC7A9; the disease is cystinuria.