Benign recurrent intrahepatic cholestasis progressing to progressive familial intrahepatic cholestasis: low GGT cholestasis is a clinical continuum

Pediatric Cholestatic Diseases: Common and Unique Pathogenic Mechanisms

Cholestasis is the predominate feature of many pediatric hepatobiliary diseases. The physiologic flow of bile requires multiple complex processes working in concert. Bile acid (BA) synthesis and excretion, the formation and flow of bile, and the enterohepatic reuptake of BAs all function to maintain the circulation of BAs, a key molecule in lipid digestion, metabolic and cellular signaling, and, as discussed in the review, a crucial mediator in the pathogenesis of cholestasis. Disruption of one or several of these steps can result in the accumulation of toxic BAs in bile ducts and hepatocytes leading to inflammation, fibrosis, and, over time, biliary and hepatic cirrhosis. Biliary atresia, progressive familial intrahepatic cholestasis, primary sclerosing cholangitis, and Alagille syndrome are four of the most common pediatric cholestatic conditions. Through understanding the commonalities and differences in these diseases, the important cellular mechanistic underpinnings of cholestasis can be greater appreciated.

Improvement of cholestatic episodes in patients with benign recurrent intrahepatic cholestasis (BRIC) treated with rifampicin. A long-term follow-up

OBJECTIVE

Patients with benign recurrent intrahepatic cholestasis (BRIC) suffer from recurrent episodes of cholestatic jaundice. Treatment options remain limited and are mainly symptomatic. In case reports rifampicin, plasmapheresis, and nasobiliary drainage have been reported to be effective. In this case series, we present long-term experience indicating disease-modifying effects of non-invasive treatment with rifampicin for recurrent cholestasis in BRIC type 1 (BRIC1).

MATERIALS AND METHODS

We included all adult BRIC1 patients diagnosed and followed up at a single centre in Bergen, Norway. Data regarding clinical and biochemical features during BRIC attacks with and without rifampicin treatment were retrieved from medical journals and a data registry.

RESULTS

Five males with BRIC1 were included. Median age at diagnosis was 22 years (range 15-41). Together they had suffered from 65 cholestatic attacks (including four documented abortive attacks). Twenty-eight attacks were treated with rifampicin alone over the last 12 years; all cases showed symptomatic relief and reduction in the levels of bilirubin and alkaline phosphatase in blood. The attacks treated with rifampicin seemed to have shorter duration and were less likely to result in complications or hospitalization compared to attacks prior to the introduction of rifampicin. No side effects attributable to rifampicin were noted.

CONCLUSIONS

Episodic treatment of recurrent BRIC1 attacks with rifampicin seems to ameliorate severity and shorten the duration of attacks. Timely diagnosis and effective treatment are of major importance in BRIC, not only to decrease complications but also improving patients' quality of life.

Case Report: A Rare Heterozygous ATP8B1 Mutation in a BRIC1 Patient: Haploinsufficiency?

Benign recurrent intrahepatic cholestasis (BRIC) is an autosomal recessive disorder characterized by recurrent cholestasis. ATPase class I, type 8B, member 1 (ATP8B1) encodes familial intrahepatic cholestasis 1 (FIC1), which acts as a phosphatidylserine reversing enzyme in the tubule membrane of hepatocytes to mediate the inward translocation of phosphatidylserine (PS). At present, dozens of ATP8B1 pathogenic mutations have been identified that mainly cause BRIC1 and progressive familial intrahepatic cholestasis 1 (PFIC1). The diagnosis of BRIC1 is based on symptoms, laboratory tests, imaging, liver histology, and genetic testing. BRIC1 treatment seeks to prevent recurrence and reduce disease severity. At present, the main treatment methods include ursodeoxycholic acid (UDCA), rifampin, cholestyramine and haemofiltration, and endoscopic nasobiliary drainage (ENBD). Here, we report a 17-year-old patient with cholestasis who has a rare heterozygous ATP8B1 gene mutation (p.T888K). The patient was treated with UDCA, glucocorticoids and haemofiltration, after which bilirubin levels gradually returned to normal. This case was thought to be caused by an ATP8B1 heterozygous mutation, which may be related to haploinsufficiency (HI).

Case Report: A Rare Case of Benign Recurrent Intrahepatic Cholestasis-Type 1 With a Novel Heterozygous Pathogenic Variant of ATP8B1

Benign recurrent intrahepatic cholestasis type 1 (BRIC1) is a rare autosomal recessive disorder that is characterized by intermittent episodes of jaundice and intense pruritus and caused by pathogenic variants of adenosine triphosphatase phospholipid transporting 8B1 (ATP8B1). The presence of genetic heterogeneity in the variants of ATP8B1 is suggested. Herein, we describe a unique clinical course in a patient with BRIC1 and a novel heterozygous pathogenic variant of ATP8B1. A 20-year-old Japanese man experienced his first cholestasis attack secondary to elevated transaminase at 17 years of age. Laboratory examinations showed no evidence of liver injury caused by viral, autoimmune, or inborn or acquired metabolic etiologies. Since the patient also had elevated transaminase and hypoalbuminemia, he was treated with ursodeoxycholic acid and prednisolone. However, these treatments did not relieve his symptoms. Histopathological assessment revealed marked cholestasis in the hepatocytes, Kupffer cells, and bile canaliculi, as well as a well-preserved intralobular bile duct arrangement and strongly expressed bile salt export pump at the canalicular membrane. Targeted next-generation sequencing detected a novel heterozygous pathogenic variant of ATP8B1 (c.1429 + 2T > G). Taken together, the patient was highly suspected of having BRIC1. Ultimately, treatment with 450 mg/day of rifampicin rapidly relieved his symptoms and shortened the symptomatic period.

Coronavirus disease 2019 (COVID‐19) as a potential trigger for benign recurrent intrahepatic cholestasis

Benign recurrent intrahepatic cholestasis (BRIC) is a rare disease characterized by recurrent severe itching and jaundice. Coronavirus disease 2019 (COVID‐19) is a multisystemic acute viral disease and the liver is frequently affected. Here, we wanted to present a BRIC case triggered by COVID‐19 infection, discussing it together with current information.

Norethisterone‐induced cholestasis: A case report

Case presentation

This case report concerns a 49‐year‐old woman who developed cholestasis (build‐up of bile in the liver) two months and a half after initiating norethisterone, progestin‐only pills, which resolved after the withdrawal of these pills.

Alkaline Phosphatase Pathophysiology with Emphasis on the Seldom-Discussed Role of Defective Elimination in Unexplained Elevations of Serum ALP – A Case Report and Literature Review

While serum alkaline phosphatase activity has become a routine clinical measurement, we have found that physicians’ knowledge of the pathophysiology of this enzyme is almost solely limited to the concept that an elevated serum alkaline phosphatase suggests disease of liver or bone. For example, physicians at all levels of training had no understanding of such basic physiological information as the function of alkaline phosphatase in the liver or how this enzyme is eliminated from the serum. Based on a patient with an enormously elevated alkaline phosphatase, this report provides a review of existing clinically relevant information concerning the pathophysiology of alkaline phosphatase with emphasis on the mechanisms involved in the homeostasis of this enzyme. A novel aspect of this paper is the discussion of the previously neglected concept that defective enzyme elimination could play a major role in the pathogenesis of serum alkaline phosphatase elevations.

Heterozygous mutations of ATP8B1, ABCB11 and ABCB4 cause mild forms of Progressive Familial Intrahepatic Cholestasis in a pediatric cohort

INTRODUCTION

Heterozygous defects in genes implicated in Progressive Familial Intrahepatic Cholestasis have been described in milder forms of cholestatic diseases. Our aim is to describe clinical, laboratory and imaging characteristics as well as treatment and outcome of a cohort of pediatric patients with heterozygous mutations in ATP8B1, ABCB11 or ABCB4.

PATIENTS AND METHODS

We present a retrospective descriptive study including pediatric patients with at least one heterozygosis defect in ATP8B1, ABCB11 or ABCB4 diagnosed after a cholestatic episode. Clinical, diagnostic and outcome data were collected including gene analysis (panel of PFIC NextGeneDx®).

RESULTS

7 patients showed a heterozygous mutation: 3 patients in ABCB4, 1 in ABCB11, 2 in ABCB4 and ABCB11 and 1 in ATP8B1. The median onset age was 5.5 years with a median time of follow-up of 6 years. The initial presentation was pruritus followed by asymptomatic hypertransaminasemia and persistent cholestasis. Two patients had family history of gallbladder stones and mild hepatitis. All showed elevated transaminases and bile acids, high gamma glutamyl-transferase (GGT) in 3 and conjugated bilirubin in 2 patients. Liver biopsy showed inflammatory infiltrate or mild fibrosis with normal immunohistochemistry. All patients were treated with ursodeoxycholic acid, two patients requiring the addition of resincholestyramine. During follow-up, 3 patients suffered limited relapses of pruritus. No disease progression was observed.

CONCLUSION

Heterozygous mutations in genes coding proteins of the hepatocellular transport system can cause cholestatic diseases with great phenotypic variability. The presence of repeated episodes of hypertransaminasemia or cholestasis after a trigger should force us to rule out the presence of these heterozygous mutations in genes involved in CIFP.

Case Report: A Novel Homozygous Variant Identified in a Chinese Patient With Benign Recurrent Intrahepatic Cholestasis-Type 1

Benign recurrent intrahepatic cholestasis (BRIC) is a rare hereditary cholestatic liver disorder. Accurate diagnosis and timely interventions are important in determining outcomes. Besides clinical and pathologic diagnosis, genetic study of BRIC remains limited. Here, we report a young man enduring recurrent jaundice and severe pruritus for 15 years. The increased level of direct bilirubin was the main biochemical abnormality, and the work-up for common causes of jaundice were unremarkable. Liver biopsy showed extensive cholestasis of hepatocytes in zone 3. The novel homozygous variant including c.1817T > C and p.I606T was detected on his ATP8B1gene. The patient was finally diagnosed with BRIC-1. His symptoms were relieved, and liver function tests returned to normal after taking ursodeoxycholic acid. This case provides a different perspective to the methodology employed when dealing with cases of jaundice and helping diagnose rare diseases.

Impact of Genotype, Serum Bile Acids, and Surgical Biliary Diversion on Native Liver Survival in FIC1 Deficiency

BACKGROUND AND AIMS

Mutations in ATPase phospholipid transporting 8B1 (ATP8B1) can lead to familial intrahepatic cholestasis type 1 (FIC1) deficiency, or progressive familial intrahepatic cholestasis type 1. The rarity of FIC1 deficiency has largely prevented a detailed analysis of its natural history, effects of predicted protein truncating mutations (PPTMs), and possible associations of serum bile acid (sBA) concentrations and surgical biliary diversion (SBD) with long-term outcome. We aimed to provide insights by using the largest genetically defined cohort of patients with FIC1 deficiency to date.

APPROACH AND RESULTS

This multicenter, combined retrospective and prospective study included 130 patients with compound heterozygous or homozygous predicted pathogenic ATP8B1 variants. Patients were categorized according to the number of PPTMs (i.e., splice site, frameshift due to deletion or insertion, nonsense, duplication), FIC1-A (n = 67; no PPTMs), FIC1-B (n = 29; one PPTM), or FIC1-C (n = 34; two PPTMs). Survival analysis showed an overall native liver survival (NLS) of 44% at age 18 years. NLS was comparable among FIC1-A, FIC1-B, and FIC1-C (% NLS at age 10 years: 67%, 41%, and 59%, respectively; P = 0.12), despite FIC1-C undergoing SBD less often (% SBD at age 10 years: 65%, 57%, and 45%, respectively; P = 0.03). sBAs at presentation were negatively associated with NLS (NLS at age 10 years, sBAs < 194 µmol/L: 49% vs. sBAs ≥ 194 µmol/L: 15%; P = 0.03). SBD decreased sBAs (230 [125-282] to 74 [11-177] μmol/L; P = 0.005). SBD (HR 0.55, 95% CI 0.28-1.03, P = 0.06) and post-SBD sBA concentrations < 65 μmol/L (P = 0.05) tended to be associated with improved NLS.

CONCLUSIONS

Less than half of patients with FIC1 deficiency reach adulthood with native liver. The number of PPTMs did not associate with the natural history or prognosis of FIC1 deficiency. sBA concentrations at initial presentation and after SBD provide limited prognostic information on long-term NLS.

Triggers of benign recurrent intrahepatic cholestasis and its pathophysiology: a review of literature

Benign recurrent intrahepatic cholestasis (BRIC) is a rare genetic disorder that is characterized by episodes of cholestasis followed by complete resolution. The episodic nature of BRIC raises concerns about its possible trigger factors. Indeed, case reports of this orphan disease have associated BRIC to some triggers. In the absence of any reviews, we reviewed BRIC trigger factors and its pathophysiology. The study consisted of a systematic search for case reports using PubMed. Articles describing a clear case of BRIC associated with a trigger were included resulting in 22 articles that describe 35 patients. Infection was responsible for 54.3% of triggered episodes, followed by hormonal, drugs, and miscellaneous causes reporting as 30%, 10%, and 5.7% respectively. Females predominated with 62.9%. The longest episode ranged between 3 months to 2 years with a mean of 32.37 weeks. The mean age of the first episode was 14.28 ranging between 3 months to 48 years. Winter and autumn were the major seasons during which episodes happened. Hence, BRIC is potentially triggered by infection, which is most commonly a viral infection, hormonal disturbances as seen in oral contraceptive pills and pregnancy state, and less commonly by certain drugs and other causes. The appearance of cholestasis during the first two trimesters of pregnancy compared to intrahepatic cholestasis of pregnancy could help to differentiate between the two conditions. The possible mechanism of BRIC induction implicates a role of BSEP and ATP8B1. While estrogen, drugs, and cytokines are known to affect BSEP, less is known about their action on ATP8B1.

New paradigms of USP53 disease: normal GGT cholestasis, BRIC, cholangiopathy, and responsiveness to rifampicin

Biallelic variants in the USP53 gene have recently been reported to segregate with normal gamma glutamyltransferase (GGT) cholestasis. Using whole-exome sequencing (WES), we detected two USP53 homozygous variants (c.951delT; p. Phe317fs and c.1744C>T; p. Arg582*) in five additional cases, including an unpublished cousin of a previously described family with intractable itching and normal GGT cholestasis. Three patients, a child and two adults, presented with recurrent episodes of normal GGT cholestasis, consistent with a diagnosis of benign recurrent intrahepatic cholestasis (BRIC). Cholangiopathic changes, possibly autoimmune in origin, were recognized in some patients. Additional phenotypic details in one patient included an enlarged left kidney, and speech/developmental delay. Notably, two patients exhibited a complete response to rifampicin, and one responded to ursodeoxycholic acid (UDCA). Two adult patients were suspected to have autoimmune liver disease and treated with steroids. This report describes new cases of USP53 disease presenting with normal GGT cholestasis or BRIC in three children and two adults. We also describe the novel finding of a dramatic response to rifampicin. The association of cholangiopathy with normal GGT cholestasis provides a diagnostic challenge and remains poorly understood.

Genotype correlates with the natural history of severe bile salt export pump deficiency

BACKGROUND & AIMS

Mutations in ABCB11 can cause deficiency of the bile salt export pump (BSEP), leading to cholestasis and end-stage liver disease. Owing to the rarity of the disease, the associations between genotype and natural history, or outcomes following surgical biliary diversion (SBD), remain elusive. We aimed to determine these associations by assembling the largest genetically defined cohort of patients with severe BSEP deficiency to date.

METHODS

This multicentre, retrospective cohort study included 264 patients with homozygous or compound heterozygous pathological ABCB11 mutations. Patients were categorized according to genotypic severity (BSEP1, BSEP2, BSEP3). The predicted residual BSEP transport function decreased with each category.

RESULTS

Genotype severity was strongly associated with native liver survival (NLS, BSEP1 median 20.4 years; BSEP2, 7.0 years; BSEP3, 3.5 years; p <0.001). At 15 years of age, the proportion of patients with hepatocellular carcinoma was 4% in BSEP1, 7% in BSEP2 and 34% in BSEP3 (p = 0.001). SBD was associated with significantly increased NLS (hazard ratio 0.50; 95% CI 0.27-0.94: p = 0.03) in BSEP1 and BSEP2. A serum bile acid concentration below 102 μmol/L or a decrease of at least 75%, each shortly after SBD, reliably predicted NLS of ≥15 years following SBD (each p <0.001).

CONCLUSIONS

The genotype of severe BSEP deficiency strongly predicts long-term NLS, the risk of developing hepatocellular carcinoma, and the chance that SBD will increase NLS. Serum bile acid parameters shortly after SBD can predict long-term NLS.

LAY SUMMARY

This study presents data from the largest genetically defined cohort of patients with severe bile salt export pump deficiency to date. The genotype of patients with severe bile salt export pump deficiency is associated with clinical outcomes and the success of therapeutic interventions. Therefore, genotypic data should be used to guide personalized clinical care throughout childhood and adulthood in patients with this disease.

Cholestasis in the Premature Infant

Liver dysfunction is a common problem in the sick premature infant. The dysfunction is usually multifactorial and often underlies a combination of liver immaturity, comorbidities, and/or the presence of primary liver disease. The liver of the preterm infant has a paucity of bile ducts, low levels of many hepatic enzymes and transporters, and a small bile acid pool. Many other organ systems are immature as well and do not respond to stress the way they would later in infancy. This articles discusses how prematurity affects the liver, how it responds to secondary insults, and approaches to evaluation.

Nonsense variant of ATP8B1 gene in heterozygosis and benign recurrent intrahepatic cholestasis: A case report and review of literature

BACKGROUND

Benign recurrent intrahepatic cholestasis is a genetic disorder with recurrent cholestatic jaundice due to ATP8B1 and ABCB11 gene mutations encoding for hepato-canalicular transporters. Herein, we firstly provide the evidence that a nonsense variant of ATP8B1 gene (c.1558A>T) in heterozygous form is involved in BRIC pathogenesis.

CASE SUMMARY

A 29-year-old male showed severe jaundice and laboratory tests consistent with intrahepatic cholestasis despite normal gamma-glutamyltranspeptidase. Acute and chronic liver diseases with viral, metabolic and autoimmune etiology were excluded. Normal intra/extra-hepatic bile ducts were demonstrated by magnetic resonance. Liver biopsy showed: Cholestasis in the centrilobular and intermediate zones with bile plugs and intra-hepatocyte pigment, Kupffer’s cell activation/hyperplasia and preserved biliary ducts. Being satisfied benign recurrent intrahepatic cholestasis diagnostic criteria, ATP8B1 and ABCB11 gene analysis was performed. Surprisingly, we found a novel nonsense variant of ATP8B1 gene (c.1558A>T) in heterozygosis. The variant was confirmed by Sanger sequencing following a standard protocol and tested for familial segregation, showing a maternal inheritance. Immunohistochemistry confirmed a significant reduction of mutated gene related protein (familial intrahepatic cholestasis 1). The patient was treated with ursodeoxycholic acid 15 mg/kg per day and colestyramine 8 g daily with total bilirubin decrease and normalization at the 6^th and 12^th mo.

CONCLUSION

A genetic abnormality, different from those already known, could be involved in familial intrahepatic cholestatic disorders and/or pro-cholestatic genetic predisposition, thus encouraging further mutation detection in this field.

TJP2 hepatobiliary disorders: Novel variants and clinical diversity

To assess the spectrum of pediatric clinical phenotypes in TJP2 disease, we reviewed records of our seven patients in whom intrahepatic cholestasis was associated with biallelic TJP2 variants (13; 12 novel) and correlated clinical manifestations with mutation type. The effect of a splicing variant was analyzed with a minigene assay. The effects of three missense variants were analyzed with protein expression in vitro. Our patients had both remitting and persistent cholestasis. Three exhibited growth retardation. Six responded to treatment with cholestyramine, ursodeoxycholic acid, or both. Two had cholecystolithiasis. None required liver transplantation or developed hepatocellular or cholangiocellular malignancy. None manifested extrahepatic disease not attributable to effects of cholestasis. The variant c.2180-5T>G resulted in exon 15 skipping with in-frame deletion of 32 amino acid residues in TJP2. The three missense variants decreased but did not abolish TJP2 expression. Patients with truncating or canonical splice-site variants had clinically more severe disease. TJP2 disease in children includes a full clinical spectrum of severity, with mild or intermittent forms as well as the severe and minimal forms hitherto described. Biallelic TJP2 variants must be considered in children with clinically intermittent or resolved intrahepatic cholestasis.

Familial intrahepatic cholestasis: New and wide perspectives

BACKGROUND

Progressive familial intrahepatic cholestasis (PFIC) includes autosomal recessive cholestatic rare diseases of childhood.

AIMS

To update the panel of single genes mutations involved in familial cholestasis.

METHODS

PubMed search for "familial intrahepatic cholestasis" alone as well as in combination with other key words was performed considering primarily original studies and meta-analyses.

RESULTS

PFIC1 involves ATP8B1 gene encoding for aminophospholipid flippase FIC1. PFIC2 includes ABCB11 gene, encoding for protein functioning as bile salt export pump. PFIC3 is due to mutations of ABCB4 gene responsible for the synthesis of class III multidrug resistance P-glycoprotein flippase. PFIC4 and PFIC5 involve tight junction protein-2 gene and NR1H4 gene encoding for farnesoid X receptor. Benign Intrahepatic Cholestasis, Intrahepatic Cholestasis of Pregnancy and Low-phospholipid-associated cholelithiasis involve the same genes and are characterized by intermittent attacks of cholestasis, no progression to cirrhosis, reversible pregnancy-specific cholestasis and cholelithiasis in young people. Blood and liver tissue levels of bile-excreted drugs can be influenced by the presence of mutations in PFIC genes, causing drug-induced cholestasis. Mutations in PFIC genes might increase the risk of liver cancer.

CONCLUSION

There is a high proportion of unexplained cholestasis potentially caused by specific genetic pathophysiologic pathways. The use of next generation sequencing and whole-exome sequencing could improve the diagnostic process in this setting.

Beyond an Obvious Cause of Cholestasis in a Toddler: Compound Heterozygosity for ABCB11 Mutations

A 27-month-old girl presented with a short history of jaundice initially attributed to drug-induced liver injury. During the preceding 20 days, she had received a 10-day course of cefprozil and 2 doses of a homeopathic preparation of cantharidin for cystitis. Severe conjugated hyperbilirubinemia was present with normal γ-glutamyl transpeptidase activity. Liver biopsy revealed marked canalicular and hepatocellular cholestasis, with moderate hepatocellular disarray, as well as evidence of chronicity, including moderate portal-tract and perisinusoidal fibrosis. Immunohistochemical studies revealed that bile salt export pump expression was preserved, whereas canalicular γ-glutamyl transpeptidase expression was largely absent. An inherited cholestatic disorder was suspected. The entire coding region of ABCB11, encoding bile salt export pump, was analyzed. The patient was found to be a compound heterozygote for the missense mutation c.3148C>T (p.Arg1050Cys) associated with benign recurrent intrahepatic cholestasis type 2 in the homozygous state and for the nonsense mutation c.3904G>T (p.Glu1302Ter) associated with progressive familial intrahepatic cholestasis type 2. Despite initial improvement with ursodeoxycholic acid, over the course of 5 years the patient developed cirrhosis that required liver transplant. Our report emphasizes the need for molecular studies even in patients with putatively "explained" cholestasis to reveal the entire spectrum of inherited cholestatic disorders.

Progressive Familial Intrahepatic Cholestasis

Genetic cholestasis has been dissected through genetic investigation. The major PFIC genes are now described. ATP8B1 encodes FIC1, ABCB11 encodes BSEP, ABCB4 encodes MDR3, TJP2 encodes TJP2, NR1H4 encodes FXR, and MYO5B encodes MYO5B. The full spectra of phenotypes associated with mutations in each gene are discussed, along with our understanding of the disease mechanisms. Differences in treatment response and targets for future treatment are emerging.

Cryptogenic cholestasis in young and adults: ATP8B1, ABCB11, ABCB4, and TJP2 gene variants analysis by high-throughput sequencing

BACKGROUND

Mutations in ATP-transporters ATPB81, ABCB11, and ABCB4 are responsible for progressive familial intrahepatic cholestasis (PFIC) 1, 2 and 3, and recently the gene for tight junction protein-2 (TJP2) has been linked to PFIC4.

AIM

As these four genes have been poorly studied in young people and adults, we investigated them in this context here.

METHODS

In patients with cryptogenic cholestasis, we analyzed the presence of mutations by high-throughput sequencing. Bioinformatics analyses were performed for mechanistic and functional predictions of their consequences on biomolecular interaction interfaces.

RESULTS

Of 108 patients, 48 whose cause of cholestasis was not established were submitted to molecular analysis. Pathogenic/likely pathogenic mutations were found in ten (21%) probands for 13 mutations: two in ATP8B 1, six in ABCB11, two in ABCB4, three in TJP2. We also identified seven variants of uncertain significance: two in ATP8B1, one in ABCB11, two in ABCB4 and two in TJP2. Finally, we identified 11 benign/likely benign variants. Patients with pathogenic/likely pathogenic mutations had higher levels of liver stiffness (measured by FibroScan^®) and bile acids, as well as higher rates of cholestatic histological features, compared to the patients without at least likely pathogenic mutations. The multivariate analysis showed that itching was the only independent factor associated with disease-causing mutations (OR 5.801, 95% CI 1.244-27.060, p = 0.025).

CONCLUSIONS

Mutations in the genes responsible for PFIC may be involved in both young and adults with cryptogenic cholestasis in a considerable number of cases, including in heterozygous status. Diagnosis should always be suspected, particularly in the presence of itching.

New Insights in Genetic Cholestasis: From Molecular Mechanisms to Clinical Implications

Cholestasis is characterised by impaired bile secretion and accumulation of bile salts in the organism. Hereditary cholestasis is a heterogeneous group of rare autosomal recessive liver disorders, which are characterised by intrahepatic cholestasis, pruritus, and jaundice and caused by defects in genes related to the secretion and transport of bile salts and lipids. Phenotypic manifestation is highly variable, ranging from progressive familial intrahepatic cholestasis (PFIC)-with onset in early infancy and progression to end-stage liver disease-to a milder intermittent mostly nonprogressive form known as benign recurrent intrahepatic cholestasis (BRIC). Cases have been reported of initially benign episodic cholestasis that subsequently transitions to a persistent progressive form of the disease. Therefore, BRIC and PFIC seem to represent two extremes of a continuous spectrum of phenotypes that comprise one disease. Thus far, five representatives of PFIC (named PFIC1-5) caused by pathogenic mutations present in both alleles of ATP8B1, ABCB11, ABCB4, TJP2, and NR1H4 have been described. In addition to familial intrahepatic cholestasis, partial defects in ATP8B1, ABCB11, and ABCB4 predispose patients to drug-induced cholestasis and intrahepatic cholestasis in pregnancy. This review summarises the current knowledge of the clinical manifestations, genetics, and molecular mechanisms of these diseases and briefly outlines the therapeutic options, both conservative and invasive, with an outlook for future personalised therapeutic strategies.

Nuclear receptor FXR, bile acids and liver damage: Introducing the progressive familial intrahepatic cholestasis with FXR mutations

The nuclear receptor farnesoid X receptor (FXR) is the master regulator of bile acids (BAs) homeostasis since it transcriptionally drives modulation of BA synthesis, influx, efflux, and detoxification along the enterohepatic axis. Due to its crucial role, FXR alterations are involved in the progression of a plethora of BAs associated inflammatory disorders in the liver and in the gut. The involvement of the FXR pathway in cholestasis development and management has been elucidated so far with a direct role of FXR activating therapy in this condition. However, the recent identification of a new type of genetic progressive familial intrahepatic cholestasis (PFIC) linked to FXR mutations has strengthen also the bona fide beneficial effects of target therapies that by-pass FXR activation, directly promoting the action of its target, namely the enterokine FGF19, in the repression of hepatic BAs synthesis with reduction of total BA levels in the liver and serum, accomplishing one of the major goals in cholestasis. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni and Peter Jansen.

Intrahepatic cholestasis in two omani siblings associated with a novel homozygous ATP8B1 mutation, c.379C>G (p.L127V)

We report two Omani brothers with intrahepatic cholestasis that resolved with supportive care. In one, cholestasis began in infancy; in the other, only at the age of 18 months. Whole exome sequencing identified a novel homozygous variant, c.379C>G (p.L127V) in ATP8B1. Those attending patients with cholestasis from the Arabian peninsula should be aware of this mutation and of the variation in its phenotypic effects.

The Features of GGT in Patients with ATP8B1 or ABCB11 Deficiency Improve the Diagnostic Efficiency

Background and Aims

Genetic defects in ATP8B1 or ABCB11 account for the majority of cholestasis with low GGT. But the ranges for GGT in patients with ATP8B1 or ABCB11 deficiency are unclear. This study tried to unravel the features of GGT in these patients that improve diagnostic efficiency.

Methods

This study enrolled 207 patients with chronic cholestasis who were ordered to test for ATP8B1 and/or ABCB11 from January 2012 to December 2015. Additional 17 patients with ATPB81 or ABCB11 deficiency diagnosed between January 2004 and December 2011 were also enrolled in this study. 600 population-matched children served as controls. Clinical data were obtained by retrospectively reviewing medical records.

Results

A total of 26 patients were diagnosed with ATP8B1 deficiency and 30 patients were diagnosed with ABCB11 deficiency. GGT levels were similar between the two disorders at any observed month of age, but varied with age. The peak GGT value was <70U/L in the 2nd~6th month of life, <60U/L in the 7th~12th month and <50U/L beyond one year. GGT levels in patients with a genetic diagnosis were different from that in patients without a genetic diagnosis and controls. Larger ranges for GGT were found in patients without a genetic diagnosis. Some controls had GGT≥70U/L in the 2nd~6th month. Of the 207 patients, 39 (18.8%) obtained a genetic diagnosis. 111 patients met the ranges described above, including all the 39 patients with ATP8B1 or ABCB11 deficiency. The sensitivity was 100.0%. The rate of a positive molecular diagnosis increased to 35.1% (39/111 vs. 39/207, X² = 10.363, P = 0.001). The remaining 96 patients exceeded the ranges described above and failed to receive a genetic diagnosis. These patients accounted for 43.8% of sequencing cost.

Conclusions

GGT levels in patients with ATP8B1 or ABCB11 deficiency varied with age. The peak GGT value was <70U/L in the 2nd~6th month of life, <60U/L in the 7th~12th month and <50U/L beyond one year.

Total biliary diversion as a treatment option for patients with progressive familial intrahepatic cholestasis and Alagille syndrome

BACKGROUND

Progressive familial intrahepatic cholestasis (PFIC) with low gamma-glutamyl transpeptidase (GGT) and Alagille syndrome are associated with persistent cholestasis and severe pruritus. Various types of biliary diversion have been used to reduce this pruritus and prevent liver dysfunction. We report our experience concerning the efficacy and safety of total biliary diversion (TBD) as an additional treatment option.

METHODS

TBD was performed in four PFIC patients and one patient with Alagille syndrome, and was accomplished by anastomosing a jejunal segment to the choledochal duct terminating as an end stoma, or by disconnecting the choledochal duct after previous cholecystojejunocutaneostomy.

RESULTS

TBD resulted in a marked improvement of symptoms and biochemical parameters in all PFIC patients. Despite relief of pruritus, cholestasis persisted in the Alagille patient. During 5-15years of follow-up, no clinical signs of fat malabsorption such as diarrhea or weight loss were encountered. However, to maintain adequate levels of fat-soluble vitamins, especially of vitamin K, substantial supplementation was necessary.

CONCLUSIONS

Total biliary diversion can be a useful surgical treatment option for patients with low-GGT PFIC and possibly also Alagille syndrome, when partial biliary diversion is insufficient. It can be performed without inducing clinical signs of fat malabsorption although individualized supplementation of fat-soluble vitamins with careful monitoring is warranted.

Pathophysiology and Diseases of the Proximal Pathways of the Biliary System

CONTEXT

Diseases of the proximal pathways of the biliary system can be divided into those that affect the interlobular bile ducts and those that affect the bile canaliculi. The former include primary biliary cirrhosis, small-duct variant of primary sclerosing cholangitis, graft-versus-host disease, and drug-induced liver injury, whereas the latter include progressive familial intrahepatic cholestasis, benign recurrent intrahepatic cholestasis, intrahepatic cholestasis of pregnancy, and drug-induced liver injury.

OBJECTIVE

To summarize the current state of knowledge of diseases of the proximal pathways of the biliary system, with special emphasis on clinical presentation, pathological features, and differential diagnosis.

DATA SOURCES

Clinicopathological information was extracted from pertinent published literature.

CONCLUSIONS

Care of the patient with cholestasis hinges on identifying the etiology. Diagnostic steps in cholestatic conditions comprise a thorough patient history, abdominal imaging, distinct serological studies, and liver biopsy. Primary biliary cirrhosis is characterized by distinctive serological and histological findings. The small-duct variant of primary sclerosing cholangitis is very rare and difficult to diagnose; imaging of the bile ducts is not helpful. Graft-versus-host disease is characterized by damage and loss of intrahepatic bile ducts. Drugs can cause injury variably at the level of bile canaliculus or the interlobular bile duct. Loss of bile ducts may be seen with primary biliary cirrhosis, primary sclerosing cholangitis, graft-versus-host disease, and drug-induced liver injury. Progressive familial intrahepatic cholestasis and progressive familial intrahepatic cholestasis represent 2 extreme ends of the spectrum of abnormalities in transporters responsible for bile formation. Intrahepatic cholestasis of pregnancy has a variable incidence in different parts of the world and may be due to abnormalities in transporter molecules.

Analysis of aberrant pre-messenger RNA splicing resulting from mutations in ATP8B1 and efficient in vitro rescue by adapted U1 small nuclear RNA

ATP8B1 deficiency is a severe autosomal recessive liver disease resulting from mutations in the ATP8B1 gene characterized by a continuous phenotypical spectrum from intermittent (benign recurrent intrahepatic cholestasis; BRIC) to progressive familial intrahepatic cholestasis (PFIC). Current therapeutic options are insufficient, and elucidating the molecular consequences of mutations could lead to personalized mutation-specific therapies. We investigated the effect on pre-messenger RNA splicing of 14 ATP8B1 mutations at exon-intron boundaries using an in vitro minigene system. Eleven mutations, mostly associated with a PFIC phenotype, resulted in aberrant splicing and a complete absence of correctly spliced product. In contrast, three mutations led to partially correct splicing and were associated with a BRIC phenotype. These findings indicate an inverse correlation between the level of correctly spliced product and disease severity. Expression of modified U1 small nuclear RNAs (snRNA) complementary to the splice donor sites strongly improved or completely rescued splicing for several ATP8B1 mutations located at donor, as well as acceptor, splice sites. In one case, we also evaluated exon-specific U1 snRNAs that, by targeting nonconserved intronic sequences, might reduce possible off-target events. Although very effective in correcting exon skipping, they also induced retention of the short downstream intron.

CONCLUSION

We systematically characterized the molecular consequences of 14 ATP8B1 mutations at exon-intron boundaries associated with ATP8B1 deficiency and found that the majority resulted in total exon skipping. The amount of correctly spliced product inversely correlated with disease severity. Compensatory modified U1 snRNAs, complementary to mutated donor splice sites, were able to improve exon definition very efficiently and could be a novel therapeutic strategy in ATP8B1 deficiency as well as other genetic diseases.

Treatment of pruritus with Prometheus dialysis and absorption system in a patient with benign recurrent intrahepatic cholestasis

Benign recurrent intrahepatic cholestasis (BRIC) is an autosomal recessive liver disorder characterized by recurrent episodes of jaundice and itching. Episodes of cholestasis last variously from 1 week to several months, may start at any age and usually resolve spontaneously. No effective treatment has been found as yet. We report a case of genetically proven BRIC in a male patient who developed three episodes of pruritus and jaundice at the age of 14, 16 and 19 years. During the third episode, he did not respond to pharmacological medical therapy, and fractionated plasma separation and absorption (FPSA, Prometheus) was performed to manage intractable pruritus. The treatment immediately alleviated pruritus, lowered serum bilirubin concentration and induced sustained remission in the 5-year follow up. FPSA seems to be a safe and effective way of treatment for BRIC in patients with severe pruritus and prolonged jaundice.

Review article: controversies in the management of primary biliary cirrhosis and primary sclerosing cholangitis

BACKGROUND

Despite considerable advances over the last two decades in the molecular understanding of cholestasis and cholestatic liver disease, little improvement has been made in diagnostic tools and therapeutic strategies.

AIMS

To critically review controversial aspects of the scientific basis for common clinical practice in primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) and to discuss key ongoing challenges to improve patient management.

METHODS

We performed a literature search using PubMed and by examining the reference lists of relevant review articles related to the clinical management of PBC and PSC. Articles were considered on the background of the European Association for the Study of the Liver (EASL) and the American Association for the Study of Liver Diseases (AASLD) practice guidelines and clinical experience of the authors.

RESULTS

Ongoing challenges in PBC mainly pertain to the improvement of medical therapy, particularly for patients with a suboptimal response to ursodeoxycholic acid. In PSC, development of medical therapies and sensitive screening protocols for cholangiocarcinoma represent areas of intense research. To rationally improve patient management, a better understanding of pathogenesis, including complications like pruritis and fatigue, is needed and there is a need to identify biomarker end-points for treatment effect and prognosis. Timing of liver transplantation and determining optimal regimens of immunosuppression post-liver transplantation will also benefit from better appreciation of pre-transplant disease mechanisms.

CONCLUSION

Controversies in the management of PBC and PSC relate to topics where evidence for current practice is weak and further research is needed.

Phospholipase D2 mediates signaling by ATPase class I type 8B membrane 1

Functional defects in ATPase class I type 8B membrane 1 (ATP8B1 or familial intrahepatic cholestasis 1, FIC1) lead to cholestasis by mechanism(s) that are not fully understood. One proposed pathophysiology involves aberrant signaling to the bile acid sensor, the farnesoid X receptor (FXR), via protein kinase C ζ (PKCζ). The following cell line-based studies investigated whether phospholipase D2 may transduce a signal from FIC1 to FXR. PLD2 gain of function led to activation of the bile salt export pump (BSEP) promoter, a well-characterized FXR response. BSEP activation by PLD2 could be blocked by abrogating either PKCζ or FXR signaling. PLD2 loss of function led to a reduction in BSEP promoter activity. In addition, a variety of proteins that are activated by FXR, including BSEP, were reduced in HepG2 cells treated with PLD2 siRNA. Similar effects were observed in freshly isolated human hepatocytes. Activation of BSEP by FIC1 gain of function was blocked when PLD2 but not PLD1 was silenced. Overexpression of wild-type but not Byler mutant FIC1 led to an increase in membrane associated PLD activity. An intermediate level of activation of PLD activity was induced when a benign recurrent intrahepatic cholestasis FIC1 mutant construct was expressed. These studies show that FIC1 signals to FXR via a signaling pathway including PLD2 and PKCζ.

Novel ATP8B1 mutation in an adult male with progressive familial intrahepatic cholestasis

Progressive familial intrahepatic cholestasis type 1 is a rare disease that is characterized by low serum γ-glutamyltransferase levels due to mutation in ATP8B1. We present a 23-year-old male who experienced persistent marked pruritus for eighteen years and recurrent jaundice for thirteen years, in addition to cholestasis that eventually became fatal. Genetic sequencing studies of the entire coding (exon) sequences of ATP8B1 and ABCB11 uncovered a novel heterozygous missense 3035G>T mutation (S1012I) and a synonymous 696T>C mutation in ATP8B1. The patient’s progression was associated with not only impaired familial intrahepatic cholestasis 1 (FIC1) function but also impaired bile salt export pump expression due to the impaired FIC1 function. Our findings show that patients with intermittent cholestasis can develop progressive liver disease even after several decades and require regular follow up.

Description of two new ABCB11 mutations responsible for type 2 benign recurrent intrahepatic cholestasis in a French-Canadian family

Benign recurrent intrahepatic cholestasis is a rare clinical entity that is caused by mutations in the canalicular transport genes. The present report describes two individuals from the same family whose symptoms were typical of the clinical characteristics of type 2 benign recurrent intrahepatic cholestasis. Sequencing of the ABCB11 gene revealed two previously unreported mutations that predict the absence of expression of the protein. The clinical presentation of the current cases are discussed, as are the differential diagnosis and genetic characteristics of the hereditary cholestatic disorders, overemphasizing the possibility of making a definite genetic diagnosis.

Clinical features and genotype-phenotype correlations in children with progressive familial intrahepatic cholestasis type 3 related to ABCB4 mutations

OBJECTIVES

The aim of the study was to estimate the frequency of ABCB4 mutations among children with chronic intrahepatic cholestasis with elevated gamma-glutamyl-transpeptidase (γ-GT) activity and to characterize the genotypes with respect to severity of symptoms, response to ursodeoxycholic acid therapy, and outcome.

PATIENTS AND METHODS

Molecular analysis of ABCB4 in 133 Italian children was performed, and ABCB4 mutations were classified as disease-causing mutations or benign substitutions according to the prediction algorithm PolyPhen.

RESULTS

: Twenty-eight patients were identified carrying 31 mutations (20 disease causing). Twenty patients carried 2 mutated alleles and 8 only 1. At presentation (1-204 months), 20 children were symptomatic with jaundice and/or pruritus, whereas in 8 biochemical cholestasis was a fortuitous finding. Cirrhosis developed in 15 and 6 progressed to terminal liver failure. Disease-causing mutations on both alleles were found to be associated with reduced liver expression of ABCB4 protein, lack of response to ursodeoxycholic acid therapy, and progression to cirrhosis and end-stage liver disease, whereas mild genotypes, including single heterozygous mutations, were generally associated with less severe disease and, often, absence of symptoms.

CONCLUSIONS

ABCB4 mutations are responsible for a chronic liver disease in more than one-third of patients with chronic intrahepatic cholestasis and elevated γ-GT activity. In patients with severe ABCB4 genotype, the disease is often progressive with risk of developing cirrhosis and liver failure during the first 2 decades of life. Patients with mild genotypes, including single heterozygous mutations, have variable expressions of liver disease that may be influenced by comorbidity factors and modulated by still unknown genetic modifiers.

Familial cholestasis: progressive familial intrahepatic cholestasis, benign recurrent intrahepatic cholestasis and intrahepatic cholestasis of pregnancy

Progressive familial intrahepatic cholestasis (PFIC) type 1, 2 and 3 are due to mutations in ATP8B1, ABCB11 and ABCB4, respectively. Each of these genes encodes a hepatocanalicular transporter, which is essential for the proper formation of bile. Mutations in ABCB4 can result in progressive cholestatic disease, while mutations in ATP8B1 and ABCB11 can result both in episodic cholestasis, referred to as benign recurrent intrahepatic cholestasis (BRIC) type 1 and 2, as well as in progressive cholestatic disease. This suggests a clinical continuum and these diseases are therefore preferably referred to as ATP8B1 deficiency and ABCB11 deficiency. Similarly PFIC type 3 is designated as ABCB4 deficiency. Heterozygous mutations in each of these transporters can also be associated with intrahepatic cholestasis of pregnancy. This review summarizes the pathophysiology, clinical features and current as well as future therapeutic options for progressive familial- and benign recurrent intrahepatic cholestasis as well as intrahepatic cholestasis of pregnancy.

Liver disease associated with canalicular transport defects: current and future therapies

Bile formation at the canalicular membrane is a delicate process. This is illustrated by inherited liver diseases due to mutations in ATP8B1, ABCB11, ABCB4, ABCC2 and ABCG5/8, all encoding hepatocanalicular transporters. Effective treatment of these canalicular transport defects is a clinical and scientific challenge that is still ongoing. Current evidence indicates that ursodeoxycholic acid (UDCA) can be effective in selected patients with PFIC3 (ABCB4 deficiency), while rifampicin reduces pruritus in patients with PFIC1 (ATP8B1 deficiency) and PFIC2 (ABCB11 deficiency), and might abort cholestatic episodes in BRIC (mild ATP8B1 or ABCB11 deficiency). Cholestyramine is essential in the treatment of sitosterolemia (ABCG5/8 deficiency). Most patients with PFIC1 and PFIC2 will benefit from partial biliary drainage. Nevertheless liver transplantation is needed in a substantial proportion of these patients, as it is in PFIC3 patients. New developments in the treatment of canalicular transport defects by using nuclear receptors as a target, enhancing the expression of the mutated transporter protein by employing chaperones, or by mutation specific therapy show substantial promise. This review will focus on the therapy that is currently available as well as on those developments that are likely to influence clinical practice in the near future.

New molecular insights into the mechanisms of cholestasis

Recent progress in basic research has enhanced our understanding of the molecular mechanisms of normal bile secretion and their alterations in cholestasis. Genetic transporter variants contribute to an entire spectrum of cholestatic liver diseases and can cause hereditary cholestatic syndromes or determine susceptibility and disease progression in acquired cholestatic disorders. Cholestasis is associated with complex transcriptional and post-transcriptional alterations of hepatobiliary transporters and enzymes participating in bile formation. Ligand-activated nuclear receptors for bile acids and other biliary compounds play a key role in the regulation of genes required for bile formation. Pharmacological interventions in cholestasis may aim at modulating such novel regulatory pathways. This review will summarize the principles of molecular alterations in cholestasis and will give an overview of potential clinical implications.

Adult progressive intrahepatic cholestasis associated with genetic variations in ATP8B1 and ABCB11

Severe intrahepatic cholestasis with low serum gamma-glutamyltranspeptidase (gamma-GT) activity is exceptionally rare in adult patients, and its association with multi-genetic alterations of bile salt transporters has not been reported. We investigated a 25-year-old man presenting with a four-year history of jaundice. Laboratory and radiographic examinations revealed clinical pictures of progressive intrahepatic cholestasis with low gamma-GT. Serial liver histopathology demonstrated cirrhosis resulting from progressive persistent cholestatic injury. Genetic sequencing studies for the entire coding exons of ATP8B1 and ABCB11 uncovered a heterozygous missense mutation 1798 C->T (R600W) in ATP8B1, and a homozygous nucleotide substitution 1331 T->C (V444A) in ABCB11. In conclusion, this is a rare case of adult onset progressive intrahepatic cholestasis with low gamma-GT associated with heterozygous ATP8B1 mutation and homozygous ABCB11 polymorphism. Further studies are necessary to investigate the impact of heterozygous R600W mutation and whether other cholestatic disorders are multi-genetic.

The membrane protein ATPase class I type 8B member 1 signals through protein kinase C zeta to activate the farnesoid X receptor

Prior loss-of-function analyses revealed that ATPase class I type 8B member 1 [familial intrahepatic cholestasis 1 (FIC1)] posttranslationally activated the farnesoid X receptor (FXR). Mechanisms underlying this regulation were examined by gain-of-function studies in UPS cells, which lack endogenous FIC1 expression. FXR function was assayed in response to wild-type and mutated FIC1 expression constructs with a human bile salt export pump (BSEP) promoter and a variety of cellular localization techniques. FIC1 overexpression led to enhanced phosphorylation and nuclear localization of FXR that was associated with FXR-dependent activation of the BSEP promoter. The FIC1 effect was lost after mutation of the FXR response element in the BSEP promoter. Despite similar levels of FIC1 protein expression, Byler disease FIC1 mutants did not activate BSEP, whereas benign recurrent intrahepatic cholestasis mutants partially activated BSEP. The FIC1 effect was dependent on the presence of the FXR ligand, chenodeoxycholic acid. The effect of FIC1 on FXR phosphorylation and nuclear localization and its effects on BSEP promoter activity could be blocked with protein kinase C zeta (PKC zeta) inhibitors (pseudosubstrate or small interfering RNA silencing). Recombinant PKC zeta directly phosphorylated immunoprecipitated FXR. The mutation of threonine 442 of FXR to alanine yielded a dominant negative protein, whereas the phosphomimetic conversion to glutamate resulted in FXR with enhanced activity and nuclear localization. Inhibition of PKC zeta in Caco-2 cells resulted in activation of the human apical sodium-dependent bile acid transporter promoter.

CONCLUSION

These results demonstrate that FIC1 signals to FXR via PKC zeta. FIC1-related liver disease is likely related to downstream effects of FXR on bile acid homeostasis. Benign recurrent intrahepatic cholestasis emanates from a partially functional FIC1 protein. Phosphorylation of FXR is an important mechanism for regulating its activity.

Preoperative observations and short-term outcome after partial external biliary diversion in 13 patients with progressive familial intrahepatic cholestasis

BACKGROUND

Patients with progressive familial intrahepatic cholestasis (PFIC) often require liver transplantation to survive. An alternative approach is surgical diversion of bile, that is, partial external biliary diversion (PEBD). The aim of the study was to describe 13 patients with PFIC who have undergone PEBD.

METHODS

Clinical and laboratory workups including growth data and histology specimens were analyzed to evaluate the short-term effects of PEBD. Follow-up, including liver biopsies, was performed 11 to 21 (median, 14) months post-PEBD.

RESULTS

All patients showed typical features of PFIC. Eight out of 13 presented with variable signs of coagulopathy, and one patient presented with hypocalcemic seizures. The surgery was uneventful in all, but 4 patients were readmitted because of dehydration and electrolyte imbalance caused by excessive stomal losses. One month post-PEBD, 7 patients were apruritic. One patient had stomal dysfunction, showed no improvement on cholestasis after surgery, and had to undergo liver transplantation 2 months post-PEBD. At follow-up, significant biochemical improvement and gains in growth were seen in most of the patients.

CONCLUSIONS

Most of the patients with PFIC presented with signs of coagulopathy. Partial external biliary diversion had a dramatic effect on cholestasis and growth, although not all patients benefited from the surgery. Episodes of dehydration post-PEBD must be considered.

Mechanisms of cholestasis

This article gives an overview of the molecular and cellular mechanisms of cholestasis. Topics reviewed include the pathomechanisms of hereditary cholestasis syndromes, such as progressive familial intrahepatic cholestasis, and hepatocellular transporter defects encountered in various acquired cholestatic disorders, such as intrahepatic cholestasis of pregnancy, drug-induced cholestasis, inflammatory cholestasis, primary sclerosing cholangitis, and primary biliary cirrhosis. In addition, current concepts regarding adaptive hepatocellular mechanisms counteracting cholestatic liver damage are discussed.