Clinical characteristics of ABCB4 gene variant-associated cholestatic liver disease in adults

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Objective: To investigate the clinical manifestations, pathological, and gene mutation characteristics of ABCB4 gene variant-associated cholestatic liver disease in adults. Methods: Eight adult cases of ABCB4 gene variant-associated cholestatic liver disease who were hospitalized in the Department of Hepatology, Fifth Medical Center of the People's Liberation Army General Hospital from May 2010 to December 2022 were enrolled in this study. The clinical manifestations, pathological features, gene variant features, and prognostic conditions were analyzed. Patient gene testing and biological information analysis were performed using whole-exome next-generation sequencing. SPSS 19.0 software was used to conduct descriptive analysis. Results: Among the eight adult cases of the ABCB4 gene variant, there were three males and five females, with a median age of onset of 24 (20, 37) years. There were three cases with a compound heterozygous variant in ABCB4, and the clinical phenotypes included two cases of progressive familial intrahepatic cholestasis type 3 and one case of intrahepatic cholestasis of pregnancy overlapping with low-phospholipid-associated cholelithiasis syndrome. There were five cases with a single heterozygous variant in ABCB4, and the clinical phenotypes included two cases of intrahepatic cholestasis of pregnancy overlapping with drug-induced liver injury and three cases of low-phospholipid-associated cholelithiasis syndrome. Imaging of all eight cases showed liver fibrosis, and six cases already had cirrhosis. All patients underwent liver histopathological examination, which mainly showed cholestasis and portal fibrosis in eight cases, small bile duct hyperplasia in seven cases, copper deposition in three cases, and cirrhosis in five cases. ABCB4 screening revealed 11 different mutations, including eight new mutations. The pathogenicity assessment showed that c.2394+82C>T (intron) was a benign mutation, and the rest were deleterious mutations. Ursodeoxycholic acid was the treatment for all patients, with a follow-up time of 7.5 (0.5, 12.7) years. One case died of end-stage liver disease, two cases developed cholestatic cirrhosis, and five cases were in stable condition. Conclusion: The adult ABCB4 gene variant-associated cholestatic liver disease are mostly single heterozygous mutations, the clinical phenotypes are diverse and overlapping, the disease is more severe in those who carried non-functional mutations.