ABCB4 mutations in adult patients with cholestatic liver disease: impact and phenotypic expression.
BACKGROUND
The ABCB4 gene encodes the MDR3 protein. Mutations of this gene cause progressive familial intrahepatic cholestasis type 3 (PFIC3) in children, but their clinical relevance in adults remains ill defined. The study of a well-characterized adult patient series may contribute to refining the genetic data regarding cholangiopathies of unknown origin. Our aim was to evaluate the impact of ABCB4 mutations on clinical expression of cholestasis in adult patients.


METHODS
We consecutively evaluated 2602 subjects with hepatobiliary disease. Biochemical evidence of a chronic cholestatic profile (CCP) with elevated serum gamma-glutamyltransferase activity or diagnosis of intrahepatic cholestasis of pregnancy (ICP) and juvenile cholelithiasis (JC) were inclusion criteria. The personal/family history of additional cholestatic liver disease (PFH-CLD), which includes ICP, JC, or hormone-induced cholestasis, was investigated. Mutation screening of ABCB4 was carried out in 90 patients with idiopathic chronic cholestasis (ICC), primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC), ICP, and JC.


RESULTS
Eighty patients had CCP. PSC and ICC patients with PFH-CLD had earlier onset of disease than those without it (p = 0.003 and p = 0.023, respectively). The mutation frequency ranged from 50% (ICP, JC) to 17.6% (PBC). Among CCP patients, presence or absence of PFH-CLD was associated with ABCB4 mutations in 26.8 vs 5.1% (p = 0.013), respectively; in the subset of ICC and PSC patients, the corresponding figures were 44.4 vs 0% (p = 0.012) and 28.6 vs 8.7% (p = 0.173).


CONCLUSIONS
Cholangiopathies attributable to highly penetrant ABCB4 mutant alleles are identifiable in a substantial proportion of adults that generally have PFH-CLD. In PSC and ICC phenotypes, patients with MDR3 deficiency have early onset of disease.
E.O. Ospedali Galliera, Laboratory of Human Genetics and Department of Experimental Medicine, University of Genoa, Genoa, Italy.|Medical Genetics Laboratory, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.
Dario
D
Degiorgio
Division of Internal Medicine and Liver Unit, School of Medicine Ospedale San Paolo, Department of Health Sciences, Università degli Studi di Milano, 20143, Milan, Italy.
Andrea
A
Crosignani
Department of Pathophysiology and Transplantation, Fondazione Ca' Granda, Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy.
Carla
C
Colombo
IRCCS Azienda Ospedaliera-Universitaria San Martino-Istituto Nazionale per la Ricerca sul Cancro, Genoa, Italy.
Domenico
D
Bordo
Division of Internal Medicine and Liver Unit, School of Medicine Ospedale San Paolo, Department of Health Sciences, Università degli Studi di Milano, 20143, Milan, Italy.
Massimo
M
Zuin
Division of Internal Medicine, Ospedale Civile di Castel San Giovanni, Piacenza, Italy.
Emanuela
E
Vassallo
Medical Genetics Laboratory, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.|Department of Clinical and Community Sciences, Division of Pediatrics, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy.
Marie-Louise
ML
Syrén
E.O. Ospedali Galliera, Laboratory of Human Genetics and Department of Experimental Medicine, University of Genoa, Genoa, Italy.
Domenico A
DA
Coviello
Division of Internal Medicine and Liver Unit, School of Medicine Ospedale San Paolo, Department of Health Sciences, Università degli Studi di Milano, 20143, Milan, Italy. piermaria.battezzati@unimi.it.
Pier Maria
http://orcid.org/0000-0003-1344-3452
PM
Battezzati
D018435:ATP Binding Cassette Transporter, Subfamily B / Q000172:deficiency / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D000595:Amino Acid Sequence; D016022:Case-Control Studies; D002648:Child; D015209:Cholangitis, Sclerosing / Q000235:genetics; D002779:Cholestasis / Q000235:genetics*; D002780:Cholestasis, Intrahepatic / Q000235:genetics; D002908:Chronic Disease; D005260:Female; D006801:Humans; D008105:Liver Cirrhosis, Biliary / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010641:Phenotype; D011248:Pregnancy Complications / Q000235:genetics; D016415:Sequence Alignment; D055815:Young Adult
D018435:ATP Binding Cassette Transporter, Subfamily B; C095122:multidrug resistance protein 3
ABCB4; Cholangiocarcinoma; Idiopathic chronic cholestasis; MDR3 protein; Primary biliary cirrhosis; Primary sclerosing cholangitis