Although 300 mutations of "ATP7B" have been described, in most populations the cases of Wilson's disease are due to a small number of mutations specific for that population. For instance, in Western populations the H1069Q mutation (replacement of a histidine by a glutamine at position 1069 in the protein) is present in 37–63% of cases, while in China this mutation is very uncommon and R778L (arginine to leucine at 778) is found more often. Relatively little is known about the relative impact of various mutations, although the H1069Q mutation seems to predict later onset and predominantly neurological problems, according to some studies. A comprehensive clinically annotated resource, WilsonGen provides clinical classification for the variants as per the recent ACMG & AMP guidelines