SOD1 and biliary dyskinesia: Sphincter of Oddi dysfunction (SOD) accounts for 1.8–31% of cases in an unselected population with PCS [14–16], and in a population pre-selected for likely SOD, true SOD was confirmed in only 25–47% of cases [17–19] based on criteria such as liver biochemistry, ERCP, or manometry [20–22].