WD is caused by mutations of a copper transporting P-type ATP synthase (ATP7B) gene in chromosome 13q14.3(2). There are over 300 mutations located throughout 21 exons of the ATP7B gene of which mutations are often compound heterozygous. However, a few common mutations occur in a high frequency as hot spots in specific populations. Arg
778Leu mutation in exon 8 has occurred at 12-39% in the East Asian populations including Chinese, Japanese, and Korean(3-5). Other mutations in exon 8, such as 2304delC and C2250G mutations are also relatively common in Chinese suggesting that exon 8 may be a hot spot for identification of WD mutations in East Asians(6). His1069Gln mutation is a common mutation in the eastern and northern European populations, which accounts for up to 49%(7,8). Some mutations appear to be common in specific countries, such as C813A mutation in India and 3402delC mutation in Brazil(9,10).