A second ABC transporter, the hepatic phosphatidylcholine translocase ABCB4, increases the risk for gallstone disease, gallbladder cancer and chronic liver diseases in general, whereas the common PNPLA3 risk variant p.I148M decreases gallstone risk.
A smaller group of patients might develop gallstones primarily due low phosphatidylcholine concentrations in bile as a result of loss-of-function mutations of the ABCB4 transporter (low phospholipid-associated cholelithiasis syndrome).
The young age of the patient, recurrence of gallstones after cholecystectomy and intrahepatic gallstones suggested a subtype of the low-phospholipid associated cholelithiasis syndrome, a monogenic form of cholesterol cholelithiasis due to variations of the ABCB4 gene that encodes the canalicular phospholipid transporter MDR3.