Progressive familial intrahepatic cholestasis type 3 revealed by oral contraceptive pills

Clinical and genetic study of ABCB4 gene-related cholestatic liver disease in China: children and adults

BACKGROUND

ABCB4 gene-related cholestatic liver diseases have a wide spectrum of clinical and genetic variations. The correlation between genotype and clinical phenotype still unclear. This study retrospectively analyzed the clinical and pathological characteristics of 23 patients with ABCB4 gene-related cholestatic liver diseases. Next-generation sequencing was used to identify the genetic causes.

RESULTS

The 23 included patients (15 children and 8 adults) were diagnosed as progressive familial intrahepatic cholestasis type 3 (PFIC3), drug-induced liver injury (DILI), cirrhosis cholestasis, cirrhosis, and mild liver fibrosis. Nineteen patients underwent liver pathological examination of the liver, exhibiting fibrosis, small bile duct hyperplasia, CK7(+), Cu(+), bile duct deletion, and cirrhosis. Thirty ABCB4 variants were identified, including 18 novel variants.

CONCLUSION

ABCB4 gene-related cholestatic liver diseases have a wide spectrum of clinical and genetic variations. Biallelic ABCB4 mutation carriers tended to severe PFIC3, which mostly occurs in children; while ABCB4 non-biallelic variants can lead to milder ICP, LACP, DILI or overlapping, mostly in adults. Thus, the ABCB4 genotype has a specific correlation with the phenotype, but there are exceptions. Non-biallelic null mutations can cause severe diseases. The mechanisms underlying this genetic phenotype require further investigation.

Case series of progressive familial intrahepatic cholestasis type 3: Characterization of variants in ABCB4 in China

Objective

To improve the accuracy of the diagnosis of familial progressive intrahepatic cholestasis type 3 (PFIC3, https://www.omim.org/entry/602347).

Materials and methods

Between September 2019 and March 2021, we recruited four patients with PFIC3 from two liver centers in East China. Molecular genetic findings of ATP-binding cassette subfamily B member 4 [ATP binding cassette transporter A4 (ABCB4), https://www.omim.org/entry/171060] were prospectively examined, and clinical records, laboratory readouts, and macroscopic and microscopic appearances of the liver were analyzed.

Results

Four patients experienced cholestasis, mild jaundice, and elevated levels of serum direct bilirubin, γ-glutamyltransferase, or total bile acids. All patients had moderate-to-severe liver fibrosis or biliary cirrhosis, and their liver biopsy specimens stained positive with rhodamine. Molecular immunohistochemistry revealed reduced or absent MDR3 expression in all liver specimens. A novel mutation of ABCB4 (c.1560 + 2T > A) was identified in patients with PFIC3, which is of high clinical significance and may help understand mutant ABCB4 pathogenesis.

Conclusion

MDR3 immunohistochemistry and molecular genetic analyses of ABCB4 are essential for the accurate diagnosis of PFIC3.

The wide phenotypic and genetic spectrum of ABCB4 gene deficiency: A case series

BACKGROUND

ABCB4-gene mutations are responsible for several cholestatic diseases with a heterogeneous clinical spectrum.

AIMS

To analyse phenotype/genotype relationships in ABCB4-mutations.

METHODS

Retrospective characterization of adult patients with ABCB4-variations diagnosed between 2015 and 2020. Genotype-phenotype correlations were analysed and compared with previously reported data.

RESULTS

Twenty patients from 12 families were included. Thirteen patients presented recurrent elevated liver tests, eight fulfilled Low-Phospholipid-Associated-Cholelithiasis syndrome criteria, five had Intrahepatic Cholestasis of Pregnancy and three patients developed Drug-Induced-Liver-Injury. ABCB4 screening identified eight different mutations. Five patients were homozygotes to the variant c.504T > C. Ten patients had one mutation in heterozygote-state and five patients had two mutations in compound-heterozygosity. Portal fibrosis occurred in two patients. One of these patients presented progressive fibrosis and progression of cholestasis despite ursodeoxycholic-acid treatment, this patient also harbours a ABCB11 polymorphism.

CONCLUSION

Although, phenotype-genotype relationships have not been clearly defined, an early diagnosis of ABCB4-variants may have an important role in management decisions and patient outcomes. To our knowledge, we describe a not previously reported deletion (c.1181delT) in ABCB4. The c.504T > C polymorphism, although a silent mutation at the protein level, seems to be associated to different cholestatic diseases. The role of other genes variants, namely ABCB11, as co-factor for progression, needs to be clarified.

Variants in ABCB4 (MDR3) across the spectrum of cholestatic liver diseases in adults

The ATP binding cassette subfamily B member 4 (ABCB4) gene on chromosome 7 encodes the ABCB4 protein (alias multidrug resistance protein 3 [MDR3]), a P-glycoprotein in the canalicular membrane of the hepatocytes that acts as a translocator of phospholipids into bile. Several variants in ABCB4 have been shown to cause ABCB4 deficiency, accounting for a disease spectrum ranging from progressive familial cholestasis type 3 to less severe conditions like low phospholipid-associated cholelithiasis, intrahepatic cholestasis of pregnancy or drug-induced liver injury. Furthermore, whole genome sequencing has shown that ABCB4 variants are associated with an increased incidence of gallstone disease, gallbladder and bile duct carcinoma, liver cirrhosis or elevated liver function tests. Diagnosis of ABCB4 deficiency-related diseases is based on clinical presentation, serum biomarkers, imaging techniques, liver histology and genetic testing. Nevertheless, the clinical presentation can vary widely and clear genotype-phenotype correlations are currently lacking. Ursodeoxycholic acid is the most commonly used medical treatment, but its efficacy has yet to be proven in large controlled clinical studies. Future pharmacological options may include stimulation/restoration of residual function by chaperones (e.g. 4-phenyl butyric acid, curcumin) or induction of ABCB4 transcription by FXR (farnesoid X receptor) agonists or PPARα (peroxisome proliferator-activated receptor-α)-ligands/fibrates. Orthotopic liver transplantation remains the last and often only therapeutic option in cirrhotic patients with end-stage liver disease or patients with intractable pruritus.

ABCB4: Insights from pathobiology into therapy

Adenosine triphosphate (ATP)-binding cassette, sub-family B, member 4 (ABCB4), also called multidrug resistance 3 (MDR3), is a member of the ATP-binding cassette transporter superfamily, which is localized at the canalicular membrane of hepatocytes, and mediates the translocation of phosphatidylcholine into bile. Phosphatidylcholine secretion is crucial to ensure solubilization of cholesterol into mixed micelles and to prevent bile acid toxicity towards hepatobiliary epithelia. Genetic defects of ABCB4 may cause progressive familial intrahepatic cholestasis type 3 (PFIC3), a rare autosomic recessive disease occurring early in childhood that may be lethal in the absence of liver transplantation, and other cholestatic or cholelithiasic diseases in heterozygous adults. Development of therapies for these conditions requires understanding of the biology of this transporter and how gene variations may cause disease. This review focuses on our current knowledge on the regulation of ABCB4 expression, trafficking and function, and presents recent advances in fundamental research with promising therapeutic perspectives.

ABCB4 mutations underlie hormonal cholestasis but not pediatric idiopathic gallstones

AIM: To investigate the contribution of ABCB4 mutations to pediatric idiopathic gallstone disease and the potential of hormonal contraceptives to prompt clinical manifestations of multidrug resistance protein 3 deficiency.

METHODS: Mutational analysis of ABCB4, screening for copy number variations by multiplex ligation-dependent probe amplification, genotyping for low expression allele c.1331T>C of ABCB11 and genotyping for variation c.55G>C in ABCG8 previously associated with cholesterol gallstones in adults was performed in 35 pediatric subjects with idiopathic gallstones who fulfilled the clinical criteria for low phospholipid-associated cholelithiasis syndrome (LPAC, OMIM #600803) and in 5 young females with suspected LPAC and their families (5 probands, 15 additional family members). The probands came to medical attention for contraceptive-associated intrahepatic cholestasis.

RESULTS: A possibly pathogenic variant of ABCB4 was found only in one of the 35 pediatric subjects with idiopathic cholesterol gallstones whereas 15 members of the studied 5 LPAC kindreds were confirmed and another one was highly suspected to carry predictably pathogenic mutations in ABCB4. Among these 16, however, none developed gallstones in childhood. In 5 index patients, all young females carrying at least one pathogenic mutation in one allele of ABCB4, manifestation of LPAC as intrahepatic cholestasis with elevated serum activity of gamma-glutamyltransferase was induced by hormonal contraceptives. Variants ABCB11 c.1331T>C and ABCG8 c.55G>C were not significantly overrepresented in the 35 examined patients with suspect LPAC.

CONCLUSION: Clinical criteria for LPAC syndrome caused by mutations in ABCB4 cannot be applied to pediatric patients with idiopathic gallstones. Sexual immaturity even prevents manifestation of LPAC.

Hepatobiliary transporters in drug-induced cholestasis: a perspective on the current identifying tools

INTRODUCTION

Impaired bile formation leads to the accumulation of cytotoxic bile salts in hepatocytes and, consequently, cholestasis and severe liver disease. Knowledge of the role of hepatobiliary transporters, especially the bile salt export pump (BSEP), in the pathogenesis of cholestasis is continuously increasing.

AREAS COVERED

This review provides an introduction into the role of these transport proteins in bile formation. It addresses the clinical relevance and pathophysiologic consequences of altered functions of these transporters by genetic mutations and drugs. In particular, the current practical aspects of identification and mitigation of drug candidates with liver liabilities employed during drug development, with an emphasis on preclinical screening for BSEP interaction, are discussed.

EXPERT OPINION

Within the potential pathogenetic mechanisms of acquired cholestasis, the inhibition of BSEP by drugs is well established. Interference of a new compound with BSEP transport activity should raise a warning sign to conduct follow-up experiments and to monitor liver function during clinical development. A combination of in vitro screening for transport interaction, in silico predicting models, and consideration of physicochemical and metabolic properties should lead to a more efficient screening of potential liver liability.

Progressive familial intrahepatic cholestasis

Progressive familial intrahepatic cholestasis (PFIC) is a group of rare disorders which are caused by defect in bile secretion and present with intrahepatic cholestasis, usually in infancy and childhood. These are autosomal recessive in inheritance. The estimated incidence is about 1 per 50,000 to 1 per 100,000 births, although exact prevalence is not known. These diseases affect both the genders equally and have been reported from all geographical areas. Based on clinical presentation, laboratory findings, liver histology and genetic defect, these are broadly divided into three types-PFIC type 1, PFIC type 2 and PFIC type 3. The defect is in ATP8B1 gene encoding the FIC1 protein, ABCB 11 gene encoding BSEP protein and ABCB4 gene encoding MDR3 protein in PFIC1, 2 and 3 respectively. The basic defect is impaired bile salt secretion in PFIC1/2 whereas in PFIC3, it is reduced biliary phospholipid secretion. The main clinical presentation is in the form of cholestatic jaundice and pruritus. Serum gamma glutamyl transpeptidase (GGT) is normal in patients with PFIC1/2 while it is raised in patients with PFIC3. Treatment includes nutritional support (adequate calories, supplementation of fat soluble vitamins and medium chain triglycerides) and use of medications to relieve pruritus as initial therapy followed by biliary diversion procedures in selected patients. Ultimately liver transplantation is needed in most patients as they develop progressive liver fibrosis, cirrhosis and end stage liver disease. Due to the high risk of developing liver tumors in PFIC2 patients, monitoring is recommended from infancy. Mutation targeted pharmacotherapy, gene therapy and hepatocyte transplantation are being explored as future therapeutic options.

Progressive familial intrahepatic cholestasis

Progressive familial intrahepatic cholestasis (PFIC) refers to a heterogeneous group of autosomal-recessive disorders of childhood that disrupt bile formation and present with cholestasis of hepatocellular origin. The exact prevalence remains unknown, but the estimated incidence varies between 1/50,000 and 1/100,000 births. Three types of PFIC have been identified and associated with mutations in hepatocellular transport-system genes involved in bile formation. PFIC1 and PFIC2 usually appear in the first months of life, whereas onset of PFIC3 may arise later in infancy, in childhood or even during young adulthood. The main clinical manifestations include cholestasis, pruritus and jaundice. PFIC patients usually develop fibrosis and end-stage liver disease before adulthood. Serum gamma-glutamyltransferase (GGT) activity is normal in PFIC1 and PFIC2 patients, but is elevated in PFIC3 patients. Both PFIC1 and PFIC2 are caused by impaired bile salt secretion due to defects in ATP8B1 encoding the FIC1 protein and in ABCB11 encoding bile salt export pump (BSEP) protein, respectively. Defects in ABCB4, encoding multidrug resistance 3 protein (MDR3), impair biliary phospholipid secretion, resulting in PFIC3. Diagnosis is based on clinical manifestations, liver ultrasonography, cholangiography and liver histology, as well as on specific tests to exclude other causes of childhood cholestasis. MDR3 and BSEP liver immunostaining, and analysis of biliary lipid composition should help to select PFIC candidates for whom genotyping could be proposed to confirm the diagnosis. Antenatal diagnosis may be proposed for affected families in which a mutation has been identified. Ursodeoxycholic acid (UDCA) therapy should be initiated in all patients to prevent liver damage. In some PFIC1 and PFIC2 patients, biliary diversion may also relieve pruritus and slow disease progression. However, most PFIC patients are ultimately candidates for liver transplantation. Monitoring of liver tumors, especially in PFIC2 patients, should be offered from the first year of life. Hepatocyte transplantation, gene therapy and specific targeted pharmacotherapy may represent alternative treatments in the future.

First description of ABCB4 gene deletions in familial low phospholipid-associated cholelithiasis and oral contraceptives-induced cholestasis

The wide clinical spectrum of the ABCB4 gene (ATP-binding cassette subfamily B member 4) deficiency syndromes in humans includes low phospholipid-associated cholelithiasis (LPAC), intrahepatic cholestasis of pregnancy (ICP), oral contraceptives-induced cholestasis (CIC), and progressive familial intrahepatic cholestasis type 3 (PFIC3). No ABCB4 mutations are found in a significant proportion of patients with these syndromes. In the present study, 102 unrelated adult patients with LPAC (43 patients) or CIC/ICP (59 patients) were screened for ABCB4 mutations using DNA sequencing. Heterozygous ABCB4 point or short insertion/deletion mutations were found in 37% (16/43) of the LPAC patients and in 27% (16/59) of the ICP/CIC patients. High-resolution gene dosage methodologies were used in the 70 negative patients. Here, we describe for the first time ABCB4 partial or complete heterozygous deletions in 7% (3/43) of the LPAC patients, and in 2% (1/59) of the ICP/CIC patients. Our observations urge to systematically test patients with LPAC, ICP/CIC, and also children with PFIC3 for the presence of ABCB4 deletions using molecular tools allowing detection of gross rearrangements. In clinical practice, a comprehensive ABCB4 alteration-screening algorithm will permit the use of ABCB4 genotyping to confirm the diagnosis of LPAC or ICP/CIC, and allow familial testing. An early diagnosis of these biliary diseases may be beneficial because of the preventive effect of ursodeoxycholic acid on biliary complications. Further comparative studies of patients with well-characterized genotypes (including deletions) and phenotypes will help determine whether ABCB4 mutation types influence clinical outcomes.

Living-donor liver transplantation for progressive familial intrahepatic cholestasis

BACKGROUND

Progressive familial intrahepatic cholestasis (PFIC) results in liver cirrhosis during the disease course, although the etiology includes unknown mechanisms. Some PFIC patients require liver transplantation (LT).

METHODS

In this study, 11 patients with PFIC type 1 (PFIC1) and 3 patients with PFIC type 2 (PFIC2) who underwent living-donor LT (LDLT) were evaluated.

RESULTS

Digestive symptoms after LDLT were confirmed in 10 PFIC1 recipients (90.9%); 8 PFIC1 recipients showed steatosis after LDLT (72.7%), which began during the early postoperative period (71.5±55.1 days). Seven of the eight steatosis-positive PFIC1 recipients (87.5%) showed a steatosis degree of ≥80%, which was complicated with steatohepatitis and resulted in fibrosis. Cirrhotic findings persisted in six PFIC1 recipients even after LDLT (54.5%), and three PFIC1 recipients finally died. The survival rates of the PFIC1 recipients at 5, 10, and 15 years were 90.9%, 72.7%, and 54.5%, respectively. In contrast, the PFIC2 recipients showed good courses and outcomes without any steatosis after LDLT.

CONCLUSIONS

The clinical courses and outcomes after LDLT are still not sufficient in PFIC1 recipients owing to steatosis/steatohepatitis and subsequent fibrosis, in contrast to PFIC2 recipients. PFIC2 is good indication for LDLT. PFIC1 patients require LT during the disease course; therefore, we suggest that the therapeutic strategies for PFIC1 patients, including the timing of LDLT, under the donor limitation should be reconsidered. The establishment of more advanced treatments for PFIC1 patients is required to improve the long-term prognosis of these patients.

Progressive familial intrahepatic cholestasis: a single-center experience of living-donor liver transplantation during two decades in Japan

BACKGROUND

Progressive familial intrahepatic cholestasis (PFIC) results in liver cirrhosis. Therefore, some PFIC patients require liver transplantation (LT). Although three types of PFIC have been identified, their etiologies include unknown mechanisms.

PATIENTS

A total of 717 recipients who underwent living-donor LT (LDLT) at <20 yr old were enrolled in this study. Among these recipients, 14 PFIC recipients comprising 11 PFIC type 1 (PFIC1) and three PFIC type 2 (PFIC2) were evaluated.

RESULTS

Three of 11 PFIC1 recipients died, while all three PFIC2 recipients survived. Eight of 11 PFIC1 recipients showed steatosis after LDLT. Among the eight steatosis-positive PFIC1 recipients, seven showed severe steatosis and seven were complicated with steatohepatitis. Nine of 11 PFIC1 recipients showed fibrosis after LDLT, and eight of the nine fibrosis-positive PFIC1 recipients showed severe fibrosis. In contrast to the PFIC1 recipients, the PFIC2 recipients did not show any steatosis or fibrosis after LDLT.

CONCLUSIONS

The clinical courses and outcomes of PFIC1 recipients after LDLT are still not sufficient owing to steatosis/fibrosis, unlike the case for PFIC2 recipients. As PFIC1 patients will require LT during the long-term progression of the disease, further strategy improvements are required for PFIC1 patients.

Progressive familial intrahepatic cholestasis

Progressive familial intrahepatic cholestasis (PFIC) refers to heterogeneous group of autosomal recessive disorders of childhood that disrupt bile formation and present with cholestasis of hepatocellular origin. The exact prevalence remains unknown, but the estimated incidence varies between 1/50,000 and 1/100,000 births.

Three types of PFIC have been identified and related to mutations in hepatocellular transport system genes involved in bile formation. PFIC1 and PFIC2 usually appear in the first months of life, whereas onset of PFIC3 may also occur later in infancy, in childhood or even during young adulthood. Main clinical manifestations include cholestasis, pruritus and jaundice. PFIC patients usually develop fibrosis and end-stage liver disease before adulthood. Serum gamma-glutamyltransferase (GGT) activity is normal in PFIC1 and PFIC2 patients, but is elevated in PFIC3 patients. Both PFIC1 and PFIC2 are caused by impaired bile salt secretion due respectively to defects in ATP8B1 encoding the FIC1 protein, and in ABCB11 encoding the bile salt export pump protein (BSEP). Defects in ABCB4, encoding the multi-drug resistant 3 protein (MDR3), impair biliary phospholipid secretion resulting in PFIC3.

Diagnosis is based on clinical manifestations, liver ultrasonography, cholangiography and liver histology, as well as on specific tests for excluding other causes of childhood cholestasis. MDR3 and BSEP liver immunostaining, and analysis of biliary lipid composition should help to select PFIC candidates in whom genotyping could be proposed to confirm the diagnosis. Antenatal diagnosis can be proposed for affected families in which a mutation has been identified. Ursodeoxycholic acid (UDCA) therapy should be initiated in all patients to prevent liver damage. In some PFIC1 or PFIC2 patients, biliary diversion can also relieve pruritus and slow disease progression. However, most PFIC patients are ultimately candidates for liver transplantation. Monitoring of hepatocellular carcinoma, especially in PFIC2 patients, should be offered from the first year of life. Hepatocyte transplantation, gene therapy or specific targeted pharmacotherapy may represent alternative treatments in the future.

Albumin liver dialysis as pregnancy-saving procedure in cholestatic liver disease and intractable pruritus

Progressive familial intrahepatic cholestasis type 3 (PFIC3) is a rare cholestatic liver disease. Such liver disease can get worse by female hormone disorder. Albumin dialysis or Molecular Adsorbent Recirculating System (MARS) has been reported to reverse severe cholestasis-linked pruritus. Here, we report the first use of MARS during a spontaneous pregnancy and its successful outcome in a patient with PFIC3 and intractable pruritus. Albumin dialysis could be considered as a pregnancy-saving procedure in pregnant women with severe cholestasis and refractory pruritus.

Prenatal molecular diagnosis of inherited cholestatic diseases

OBJECTIVES

Progressive familial intrahepatic cholestasis (PFIC) and to a lesser extent, Alagille syndrome, often lead to end-stage liver disease during childhood. We report our experience of DNA-based prenatal diagnosis of PFIC1-3 and Alagille syndrome.

PATIENTS AND METHODS

Four molecular antenatal diagnoses were performed in 3 PFIC families and 17 in 11 Alagille syndrome families. DNA was isolated from chorionic villus or cultured amniocyte samples from women, without pregnancy complications.

RESULTS

All four foetuses with a family history of PFIC1, 2, or 3 were heterozygous for an ATP8B1, ABCB11, or ABCB4 mutation and pregnancies were continued. Three of the infants were healthy after birth, and 1 premature infant, who had an ABCB4 mutation, experienced transient neonatal cholestasis. Among the families with a history of de novo JAG1 mutation, none of the foetuses was mutated, versus 40% of those with a history of familial mutation. Of 4 pregnant women with a JAG1-mutated foetus, 3 cut short their pregnancy and 1 gave birth to a child with overt Alagille syndrome.

CONCLUSIONS

Molecular antenatal diagnosis of PFIC1-3 and Alagille syndrome is reliable because clinical outcome after birth corresponded to molecular foetal data.

Linkage between a new splicing site mutation in the MDR3 alias ABCB4 gene and intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is defined as pruritus and elevated bile acid serum concentrations in late pregnancy. Splicing mutations have been described in the multidrug resistance p-glycoprotein 3 (MDR3, ABCB4) gene in up to 20% of ICP women. Pedigrees studied were not large enough for linkage analysis. Ninety-seven family members of a woman with proven ICP were asked about pruritus in earlier pregnancies, birth complications and symptomatic gallstone disease. The familial cholestasis type 1 (FIC1, ATP8B1) gene, bile salt export pump (BSEP, ABCB11) and MDR3 gene were analyzed in 55 relatives. We identified a dominant mode of inheritance with female restricted expression and a new intronic MDR3 mutation c.3486+5G>A resulting in a 54 bp (3465-3518) inframe deletion via cryptic splicing site activation. Linkage analysis of the ICP trait versus this intragenic MDR3 variant yielded a LOD score of 2.48. A Bayesian analysis involving MDR3, BSEP, FIC1 and an unknown locus gave a posterior probability of >0.9966 in favor of MDR3 as causative ICP locus. During the episode of ICP the median gamma-glutamyl transpeptidase (gamma-GT) activity was 10 U/l (95% CI, 6.9 to 14.7 U/l) in the index woman. Four stillbirths were reported in seven heterozygous women (22 pregnancies) and none in five women (14 pregnancies) without MDR3 mutation. Symptomatic gallstone disease was more prevalent in heterozygous relatives (7/21) than in relatives without the mutation (1/34), (P = 0.00341).

CONCLUSION

This study demonstrates that splicing mutations in the MDR3 gene can cause ICP with normal gamma-GT and may be associated with stillbirths and gallstone disease.

Mutations and polymorphisms in the bile salt export pump and the multidrug resistance protein 3 associated with drug-induced liver injury

OBJECTIVES

Increasing evidence suggests that a genetically determined functional impairment of the hepatocellular efflux transporters bile salt export pump (BSEP, ABCB11) and multidrug resistance protein 3 (MDR3, ABCB4) play a pathophysiological role in the development of drug-induced liver injury. The aim of this study was therefore to describe the extent of genetic variability in ABCB11 and ABCB4 in patients with drug-induced liver injury and to in vitro functionally characterize newly detected ABCB11 mutations and polymorphisms.

METHODS

ABCB11 and ABCB4 were sequenced in 23 patients with drug-induced cholestasis and 13 patients with drug-induced hepatocellular injury. Ninety-five healthy Caucasians served as the control group. Reference and mutant BSEP were expressed in Sf9 cells and ATP-dependent transport of [H]-taurocholate was measured in a rapid filtration assay.

RESULTS

Four highly conserved nonsynonymous mutations were specific for drug-induced liver injury [ABCB11: D676Y (drug-induced cholestasis) and G855R (drug-induced cholestasis); ABCB4: I764L (drug-induced cholestasis) and L1082Q (drug-induced hepatocellular injury)]. Furthermore, a polymorphism in exon 13 of ABCB11 (V444A), which is associated with decreased hepatic BSEP expression was significantly more frequent in drug-induced cholestasis patients than in drug-induced hepatocellular injury patients and healthy controls (76 versus 50 and 59% in drug-induced cholestasis patients, drug-induced hepatocellular injury patients and healthy controls, respectively; P<0.05). The in-vitro transport activity of the V444A and the D676Y BSEP constructs was similar, whereas the G855R mutation was nonfunctional.

CONCLUSION

In summary, our data support a role of ABCB11 and ABCB4 mutations and polymorphisms in drug-induced cholestasis. Genotyping of selected patients with acquired cholestasis might help to identify individuals with a genetic predisposition.

Cholestatic syndromes

PURPOSE OF REVIEW

This review highlights recent developments in the molecular pathogenesis of cholestasis as well new aspects of pathogenesis and management of clinical cholestatic disorders.

RECENT FINDINGS

Highlights include the role of nuclear receptors including FXR ligands as potential therapeutic agents, new genetic defects for pediatric cholestasis and sclerosing cholangitis, and novel infections and environmental agents as etiologies for primary biliary cirrhosis. Important clinical studies have been published in the area of pediatric cholestatic syndromes, intrahepatic cholestasis of pregnancy, primary biliary cirrhosis, primary and secondary sclerosing cholangitis, cholestasis of sepsis, viral cholestatic syndromes, and drug-induced cholestasis.

SUMMARY

These advances continue to improve understanding of the pathophysiology, diagnosis, and management of cholestatic liver disease.