Polymorphisms in canine ATP7B: candidate modifier of copper toxicosis in the Bedlington terrier

A COMMD1(MURR1) deletion has been reported as the cause of copper toxicosis (CT) in Bedlington terriers. Recent studies identified Bedlington terriers with copper accumulation without homozygous COMMD1 deletions. Wilson disease in humans is a copper storage disorder similar to CT caused by mutations in ATP7B, and COMMD1 has been shown to interact with the ATP7B protein. ATP7B may act as a modifier in CT, allowing for copper accumulation in Bedlington terriers with one deletion or other variations in COMMD1. In this study, ATP7B was cloned and sequence analysis conducted in a subset of Bedlington terriers from a pedigree that does not show complete association between the COMMD1 deletion and CT. Eleven polymorphisms, two in the coding region, were identified in the Bedlington terrier ATP7B gene. However, these are not unique to the Bedlington terrier and pedigree analysis suggests that ATP7B is not a modifier of COMMD1 in this subset of dogs.