Medical errors related to inappropriate genetic testing in liver transplant patients

Genetic testing of genes that encode proteins expressed by liver hepatocytes (clotting factors, alpha 1-antitrypsin, cytochrome P450 enzymes) is common in clinical practice. These tests use DNA extracted from peripheral blood lymphocytes (PBL) and are based on the assumption that PBL DNA can be used as a surrogate for hepatocyte DNA. However, in individuals who have undergone liver transplantation, hepatocyte DNA is that of the donor while PBL DNA remains that of the recipient. It follows that in liver transplant patients, genetic testing of the recipient's PBL DNA does not provide accurate results for proteins expressed by donor hepatocytes. Therefore, genetic testing of clotting factors, alpha 1-1-antitrypsin, cytochrome P450 enzymes, and other proteins expressed by hepatocytes is unreliable and inappropriate in liver transplant patients (inappropriate genetic testing). A review of the records of 215 consecutive liver transplant patients at our institution identified: one medical error and one near-miss medical error related to inappropriate genetic testing, 14 cases of inappropriate genetic testing, and 21 unnecessary duplicate genetic testing requests. We recommend laboratories performing genetic testing create systems to prevent inappropriate and duplicate genetic testing and that physicians be cognizant of the appropriate indications for genetic testing in liver transplant patients.