ATP7B and Wilson disease: However, mutations occurring in the TM4 structural domain of the ATP7B protein, i.e., c.2310C > G (p.Leu770Leu), are rare in WD patients, but there is still evidence in the literature, such as a 2011 statistic on the prevalence of mutations in the ATP7B gene in WD patients from Iran, where this de novo mutation had been reported (21).