ABCB4-related disease is the syndrome of bile secretion disorder caused by gene mutations and can cause bile duct injury, portal hypertension, and liver cirrhosis in clinical practice. With the development of genetics and gene sequencing techniques in recent years, more and more mutation sites have been identified; however, since this is a relatively complex disease, the pathogenicity and pathogenic mechanism of mutations remain unclear. Meanwhile, since this disease is rare, it is difficult to determine the pathogenicity of ABCB4 mutations based on basic research or clinical data. Therefore, it is urgent to establish the association between ABCB4 genotypes and phenotypes and construct a complete system in basic research and clinical practice.

Objective To investigate the etiological and clinical features of patients with unexplained liver disease manifesting as isolated jaundice and the value of whole-exome sequencing in the diagnosis of such diseases. Methods A retrospective analysis was performed for the clinical data of the patients who attended Nanjing Second Hospital due to unexplained liver disease and underwent whole-exome sequencing from February 2017 to December 2021, and according to liver function parameters and imaging data, all cases were classified based on clinical phenotype and were diagnosed based on the whole-exome sequencing report. The Mann-Whitney U test was used for comparison of non-normally distributed continuous data between two groups, and the Kruskal-Wallis H test was used for comparison between multiple groups. Results A total of 519 patients underwent whole-exome sequencing, among whom 102 patients with missing or incomplete clinical data were excluded, and finally 417 patients were included in analysis, among whom 91(91/417, 21.82%) had the manifestation of isolated jaundice. The etiology of jaundice was not determined by whole-exome sequencing in 8 patients (8/91, 8.79%). With reference to genetic testing results, 83 patients (83/91, 91.21%) had a confirmed diagnosis, among whom there were 68 patients with hereditary hyperbilirubinemia (68/91, 74.72%), 3 patients with hereditary spherocytosis (3/91, 3.30%), 2 patients with pyruvate kinase deficiency (2/91, 2.20%), and 10 patients with UGT1A1 gene disease combined with other diseases (10/91, 10.99%). Hereditary hyperbilirubinemia was the main etiology, and there were 61 patients with UGT1A1 gene disease (61/91, 67.03%), 5 patients with Dubin-Johnson syndrome (5/91, 5.49%) and 2 patients with Rotor syndrome (2/91, 2.20%). There was a significant difference in indirect bilirubin/total bilirubin ratio between the patients with the different diagnoses above ( H =22.835, P < 0.05), and the patients with UGT1A1 gene disease and other diseases had a significantly higher level of total bilirubin than those with UGT1A1 gene disease alone [95.8 (37.5-187.1) μmol/L vs 51.4 (34.8-267.1) μmol/L, Z =-2.372, P =0.018]. Conclusion Whole-exome sequencing can help with the diagnosis of most cases of unexplained liver disease manifesting as isolated jaundice. Hereditary hyperbilirubinemia is the main etiology, and UGT1A1 gene disease is the most common disease. Whole-exome sequencing can assist the clinical diagnosis of unexplained liver disease manifesting as isolated jaundice.

Objective To investigate the clinical and pathological features of progressive familial intrahepatic cholestasis type 3 (PFIC3). Methods A retrospective analysis was performed for 1326 patients with unexplained liver disease who attended Nanjing Second Hospital from January 2017 to December 2019, among whom 8 patients were diagnosed with PFIC3 based on clinical/pathological manifestation and gene sequencing results (1 patient did not undergo liver biopsy due to contraindication). Clinical, laboratory, imaging, and pathological findings were analyzed and a literature review was performed for the pathology of ABCB4-related diseases to summarize the clinical and pathological features of PFIC-3. Results Among the 8 patients with PFIC3, there were 5 male patients and 3 female patients, with a median age of 29.5 years. Of all 8 patients, 4 (50%) manifested as chronic cholestasis and 4 (50%) manifested as biliary cirrhosis, among whom 3 (75%) had the manifestation of portal hypertension. As for biochemical examination, 75% (6/8) had an increase in alkaline phosphatase, and 100% (8/8) had an increase in gamma-glutamyl transpeptidase. As for imaging examination, 50% (4/8) had cholecystitis, 25% (2/8) had gallstones, 25% (2/8) had bile duct dilatation, 75% (6/8) had splenomegaly, and 25% (2/8) had liver cirrhosis. As for liver biopsy, all 7 patients manifested as bile duct injury and/or reduction, and 57.1% (5/7) had absence of the bile duct. Multidrug resistance P-glycoprotein 3 (MDR3) immunohistochemical staining showed normal expression in 42.9% (3/7) of the patients and reduced expression in 57.1% (4/7) of the patients. Literature review obtained 17 articles with a description of the bile duct or MDR3 immunohistochemistry. Among the 7 patients with low phospholipid-associated cholelithiasis, 71.4% (5/7) had normal bile duct, 14.3% (1/7) had bile duct reduction, and 14.3% (1/7) had absence of the bile duct; among the 6 patients with intrahepatic cholestasis of pregnancy, 16.7% (1/6) had normal bile duct, 50% (3/6) had bile duct reduction, and 33.3% (2/6) had absence of the bile duct; among the 8 patients with PFIC3, 25% (2/8) had bile duct reduction and 75% (6/8) had absence of bile duct; among the 21 patients with PFIC3, 9.5% (2/21) had normal expression of MDR3, 23.8% (5/21) had a reduction in the expression of MDR3, and 66.7% (14/21) had absence of the expression of MDR3. Conclusion PFIC3 mainly manifests as cholestasis, cholelithiasis, and hepatic fibrosis. Pathological manifestation includes bile duct injury and bile duct reduction or absence of the bile duct in severe cases, and the degree of injury is associated with disease severity. MDR3 immunohistochemistry may show normal expression, reduced expression, or absence of expression, and diagnosis cannot be excluded in patients with normal expression. Genetic testing can be performed for diagnosis when necessary.