Clinical phenotype of adult-onset liver disease in patients with variants in ABCB4, ABCB11, and ATP8B1

EASL Clinical Practice Guidelines on genetic cholestatic liver diseases

Genetic cholestatic liver diseases are caused by (often rare) mutations in a multitude of different genes. While these diseases differ in pathobiology, clinical presentation and prognosis, they do have several commonalities due to their cholestatic nature. These Clinical Practice Guidelines (CPGs) offer a general approach to genetic testing and management of cholestatic pruritus, while exploring diagnostic and treatment approaches for a subset of genetic cholestatic liver diseases in depth. An expert panel appointed by the European Association for the Study of the Liver has created recommendations regarding diagnosis and treatment, based on the best evidence currently available in the fields of paediatric and adult hepatology, as well as genetics. The management of these diseases generally takes place in a tertiary referral centre, in order to provide up-to-date approaches and expertise. These CPGs are intended to support hepatologists (for paediatric and adult patients), residents and other healthcare professionals involved in the management of these patients with concrete recommendations based on currently available evidence or, if not available, on expert opinion.

Diagnosis and management of benign recurrent intrahepatic cholestasis and psychosocial stressors in an adolescent: A case report

BACKGROUND

Benign recurrent intrahepatic cholestasis (BRIC) is a rare autosomal recessive disorder, characterized by episodes of intense pruritus, elevated serum levels of alkaline phosphatase and bilirubin, and near-normal -glutamyl transferase. These episodes may persist for weeks to months before spontaneously resolving, with patients typically remaining asymptomatic between occurrences. Diagnosis entails the evaluation of clinical symptoms and targeted genetic testing. Although BRIC is recognized as a benign genetic disorder, the triggers, particularly psychosocial factors, remain poorly understood.

CASE SUMMARY

An 18-year-old Chinese man presented with recurrent jaundice and pruritus after a cold, which was exacerbated by self-medication involving vitamin B and paracetamol. Clinical and laboratory evaluations revealed elevated levels of bilirubin and liver enzymes, in the absence of viral or autoimmune liver disease. Imaging excluded biliary and pancreatic abnormalities, and liver biopsy demonstrated centrilobular cholestasis, culminating in a BRIC diagnosis confirmed by the identification of a novel ATP8B1 gene mutation. Psychological assessment of the patient unveiled stress attributable to academic and familial pressures, regarded as potential triggers for BRIC. Initial relief was observed with ursodeoxycholic acid and cetirizine, followed by an adjustment of the treatment regimen in response to elevated liver enzymes. The patient's condition significantly improved following a stress-related episode, thanks to a comprehensive management approach that included psychosocial support and medical treatment.

CONCLUSION

Our research highlights genetic and psychosocial influences on BRIC, emphasizing integrated diagnostic and management strategies.

What's new in pediatric genetic cholestatic liver disease: advances in etiology, diagnostics and therapeutic approaches

PURPOSE OF REVIEW

To highlight recent advances in pediatric cholestatic liver disease, including promising novel prognostic markers and new therapies.

FINDINGS

Identification of additional genetic variants associated with progressive familial intrahepatic cholestasis (PFIC) phenotype and new genetic cholangiopathies, with an emerging role of ciliopathy genes. Genotype severity predicts outcomes in bile salt export pump (BSEP) deficiency, and post-biliary diversion serum bile acid levels significantly affect native liver survival in BSEP and progressive familial intrahepatic cholestasis type 1 (FIC1 deficiency) patients. Heterozygous variants in the MDR3 gene have been associated with various cholestatic liver disease phenotypes in adults. Ileal bile acid transporter (IBAT) inhibitors, approved for pruritus in PFIC and Alagille Syndrome (ALGS), have been associated with improved long-term quality of life and event-free survival.

SUMMARY

Next-generation sequencing (NGS) technologies have revolutionized diagnostic approaches, while discovery of new intracellular signaling pathways show promise in identifying therapeutic targets and personalized strategies. Bile acids may play a significant role in hepatic damage progression, suggesting their monitoring could guide cholestatic liver disease management. IBAT inhibitors should be incorporated early into routine management algorithms for pruritus. Data are emerging as to whether IBAT inhibitors are impacting disease biology and modifying the natural history of the cholestasis.

UK guideline on the transition and management of childhood liver diseases in adulthood

INTRODUCTION

Improved outcomes of liver disease in childhood and young adulthood have resulted in an increasing number of young adults (YA) entering adult liver services. The adult hepatologist therefore requires a working knowledge in diseases that arise almost exclusively in children and their complications in adulthood.

AIMS

To provide adult hepatologists with succinct guidelines on aspects of transitional care in YA relevant to key disease aetiologies encountered in clinical practice.

METHODS

A systematic literature search was undertaken using the Pubmed, Medline, Web of Knowledge and Cochrane database from 1980 to 2023. MeSH search terms relating to liver diseases ('cholestatic liver diseases', 'biliary atresia', 'metabolic', 'paediatric liver diseases', 'autoimmune liver diseases'), transition to adult care ('transition services', 'young adult services') and adolescent care were used. The quality of evidence and the grading of recommendations were appraised using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system.

RESULTS

These guidelines deal with the transition of YA and address key aetiologies for the adult hepatologist under the following headings: (1) Models and provision of care; (2) screening and management of mental health disorders; (3) aetiologies; (4) timing and role of liver transplantation; and (5) sexual health and fertility.

CONCLUSIONS

These are the first nationally developed guidelines on the transition and management of childhood liver diseases in adulthood. They provide a framework upon which to base clinical care, which we envisage will lead to improved outcomes for YA with chronic liver disease.

Genetics of liver disease in adults

Chronic liver disease stands as a significant global health problem with an estimated 2 million annual deaths across the globe. Combining the use of next-generation sequencing technologies with evolving knowledge in the interpretation of genetic variation across the human genome is propelling our understanding, diagnosis, and management of both rare and common liver diseases. Here, we review the contribution of risk and protective alleles to common forms of liver disease, the rising number of monogenic diseases affecting the liver, and the role of somatic genetic variants in the onset and progression of oncological and non-oncological liver diseases. The incorporation of genomic information in the diagnosis and management of patients with liver disease is driving the beginning of a new era of genomics-informed clinical hepatology practice, facilitating personalized medicine, and improving patient care.

Clinical outcomes of ABCB4 heterozygosity in infants and children with cholestatic liver disease

OBJECTIVES

Biallelic variants in the adenosine triphosphate binding cassette subfamily B member 4 (ABCB4) gene which encodes the multidrug resistance 3 protein (MDR3) leads to progressive familiar intrahepatic cholestasis type 3. However, monoallelic variants are increasingly recognized as contributing to liver disease in adults. Our aim was to describe the clinical characteristics of MDR3 heterozygous variants in a large cohort of infants and children with cholestatic liver disease.

METHODS

The clinical and genotypic data on pediatric patients seen at King's College Hospital, London, between 2004 and 2022 and found to harbour heterozygous variants in ABCB4 were reviewed.

RESULTS

Ninety-two patients amongst 1568 tested were identified with a monoallelic variant (5.9%). The most common presenting problem was conjugated hyperbilirubinemia (n = 46; 50%) followed by cholelithiasis (n = 12; 13%) and cholestatic hepatitis (n = 10; 11%). The median values of liver biochemistry at presentation were: GGT 105 IU/L and total bilirubin 86 µmol/L. Thirty-two genetic variants were identified including 22 missense (69%), 4 deletions (13%), 5 splice site (16%) and 1 termination (3%). At a median follow up of 1 year there was resolution of liver disease.

CONCLUSIONS

Rare variants in ABCB4 were found amongst infants and children with cholestatic liver disease. The presenting problems were variable and abnormalities tended to normalize over time. Those with severe mutations could develop liver disease later in life when exposed to further insult and should be counseled appropriately.

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.

Postinfantile Giant Cell Hepatitis in Native and Allograft Livers: A Multi-Institutional Clinicopathologic Study of 70 Cases

Postinfantile giant cell hepatitis (PIGCH) is a rare hepatitis pattern in adults with variable etiologies and clinical outcomes. We conducted a multi-institutional retrospective study to define the clinicopathologic characteristics of patients with PIGCH. A total of 70 PIGCH cases were identified and reviewed for pathological features, including fibrosis, cholestasis, inflammation, steatosis, necrosis, and apoptosis, as well as the distribution of giant cells and the maximum number of giant cells per high-power field. Demographic and clinical data, including age, sex, laboratory results, etiologies, and follow-up results, were recorded. Among the 70 cases, 40% (28/70) were associated with autoimmune liver diseases, followed by 9 (13%) with unknown etiology, 8 (11%) with viral infection, 5 (7%) with medications, 5 with combined etiologies, and 4 (6%) with malignancies (mostly chronic lymphocytic leukemia). Notably, another 16% were de novo PIGCH in liver allografts, most of which occurred after a rejection event. During follow-up, 26 (37%) patients died of the disease and 44 (63%) were alive. Deceased patients were characterized by older age (mean age, 54.9 vs 45.5 years; P = .02), higher alkaline phosphatase level (mean value, 253.3U/L vs 166.3 U/L; P = .03), higher fibrosis stage (stage 3-4 vs stage 0-2, 57.7% vs 29.6%; P = .03), being more likely to have de novo PIGCH after transplantation (23.1% vs 11.4%; P = .04), and being less likely to have primary autoimmune liver disease etiology (26.9% vs 47.7%; P = .04). These results indicate that PIGCH is a rare pattern of liver injury associated with different etiologies and variable clinical outcomes. Autoimmune liver disease with PIGCH is associated with better survival, whereas de novo PIGCH in allografts is associated with poorer survival. Older age, higher alkaline phosphatase level, and advanced fibrosis are adverse prognostic factors.

Hepatology Genome Rounds: An interdisciplinary approach to integrate genomic data into clinical practice

In the last decade, the utility of whole-exome sequencing in uncovering genetic aetiologies of a variety of liver diseases has been demonstrated. These new diagnoses have guided the management, treatment, and prognostication of previously undiagnosed patients, largely thanks to improved insight into the underlying pathogenesis of their conditions. Despite its clear benefits, the uptake of genetic testing by hepatologists has been limited, in part due to limited prior genetic training and/or opportunities for continuing education. Herein, we show that Hepatology Genome Rounds, an interdisciplinary forum highlighting hepatology cases of clinical interest and educational value, are an important venue for integrating genotypic and phenotypic information to enable accurate diagnosis and appropriate management, dissemination of genomic knowledge within the field of hepatology, and ongoing education to providers and trainees in genomic medicine. We describe our single-centre experience and discuss practical considerations for clinicians interested in launching such a series. We foresee that this format will be adopted at other institutions and by additional specialties, with the aim of further incorporating genomic information into clinical medicine.

Outcomes of 38 patients with PFIC3: Impact of genotype and of response to ursodeoxycholic acid therapy

Background & Aims

Progressive familial intrahepatic cholestasis type 3 (PFIC3) is a rare liver disease caused by biallelic variations in ABCB4. Data reporting on the impact of genotype and of response to ursodeoxycholic acid (UDCA) therapy on long-term outcomes are scarce.

Methods

We retrospectively describe a cohort of 38 patients with PFIC3 with a median age at last follow-up of 19.5 years (range 3.8-53.8).

Results

Twenty patients presented with symptoms before 1 year of age. Thirty-one patients received ursodeoxycholic acid (UDCA) therapy resulting in serum liver test improvement in 20. Twenty-seven patients had cirrhosis at a median age of 8.1 years of whom 18 received a liver transplant at a median age of 8.5 years. Patients carrying at least one missense variation were more likely to present with positive (normal or decreased) canalicular MDR3 expression in the native liver and had prolonged native liver survival (NLS; median 12.4 years [range 3.8-53.8]). In contrast, in patients with severe genotypes (no missense variation), there was no detectable canalicular MDR3 expression, symptom onset and cirrhosis occurred earlier, and all underwent liver transplantation (at a median age of 6.7 years [range 2.3-10.3]). The latter group was refractory to UDCA treatment, whereas 87% of patients with at least one missense variation displayed an improvement in liver biochemistry in response to UDCA. Biliary phospholipid levels over 6.9% of total biliary lipid levels predicted response to UDCA. Response to UDCA predicted NLS.

Conclusions

Patients carrying at least one missense variation, with positive canalicular expression of MDR3 and a biliary phospholipid level over 6.9% of total biliary lipid levels were more likely to respond to UDCA and to exhibit prolonged NLS.

Impact and implications

In this study, data show that genotype and response to ursodeoxycholic acid therapy predicted native liver survival in patients with PFIC3 (progressive familial intrahepatic cholestasis type 3). Patients carrying at least one missense variation, with positive (decreased or normal) immuno-staining for canalicular MDR3, and a biliary phospholipid level over 6.9% of total biliary lipids were more likely to respond to ursodeoxycholic acid therapy and to exhibit prolonged native liver survival.

Advancing diagnosis and management of liver disease in adults through exome sequencing

BACKGROUND

Whole-exome sequencing (WES) is an effective tool for diagnosis in patients who remain undiagnosed despite a comprehensive clinical work-up. While WES is being used increasingly in pediatrics and oncology, it remains underutilized in non-oncological adult medicine, including in patients with liver disease, in part based on the faulty premise that adults are unlikely to harbor rare genetic variants with large effect size. Here, we aim to assess the burden of rare genetic variants underlying liver disease in adults at two major tertiary referral academic medical centers.

METHODS

WES analysis paired with comprehensive clinical evaluation was performed in fifty-two adult patients with liver disease of unknown etiology evaluated at two US tertiary academic health care centers.

FINDINGS

Exome analysis uncovered a definitive or presumed diagnosis in 33% of patients (17/52) providing insight into their disease pathogenesis, with most of these patients (12/17) not having a known family history of liver disease. Our data shows that over two-thirds of undiagnosed liver disease patients attaining a genetic diagnosis were being evaluated for cholestasis or hepatic steatosis of unknown etiology.

INTERPRETATION

This study reveals an underappreciated incidence and spectrum of genetic diseases presenting in adulthood and underscores the clinical value of incorporating exome sequencing in the evaluation and management of adults with liver disease of unknown etiology.

FUNDING

S.V. is supported by the NIH/NIDDK (K08 DK113109 and R01 DK131033-01A1) and the Doris Duke Charitable Foundation Grant #2019081. This work was supported in part by NIH-funded Yale Liver Center, P30 DK34989.

Molecular and Clinical Links between Drug-Induced Cholestasis and Familial Intrahepatic Cholestasis

Idiosyncratic Drug-Induced Liver Injury (iDILI) represents an actual health challenge, accounting for more than 40% of hepatitis cases in adults over 50 years and more than 50% of acute fulminant hepatic failure cases. In addition, approximately 30% of iDILI are cholestatic (drug-induced cholestasis (DIC)). The liver's metabolism and clearance of lipophilic drugs depend on their emission into the bile. Therefore, many medications cause cholestasis through their interaction with hepatic transporters. The main canalicular efflux transport proteins include: 1. the bile salt export pump (BSEP) protein (ABCB11); 2. the multidrug resistance protein-2 (MRP2, ABCC2) regulating the bile salts' independent flow by excretion of glutathione; 3. the multidrug resistance-1 protein (MDR1, ABCB1) that transports organic cations; 4. the multidrug resistance-3 protein (MDR3, ABCB4). Two of the most known proteins involved in bile acids' (BAs) metabolism and transport are BSEP and MDR3. BSEP inhibition by drugs leads to reduced BAs' secretion and their retention within hepatocytes, exiting in cholestasis, while mutations in the ABCB4 gene expose the biliary epithelium to the injurious detergent actions of BAs, thus increasing susceptibility to DIC. Herein, we review the leading molecular pathways behind the DIC, the links with the other clinical forms of familial intrahepatic cholestasis, and, finally, the main cholestasis-inducing drugs.

Histological evaluation in biliary diseases

PURPOSE OF REVIEW

This review focuses on recent developments of histopathology in the most common biliary disorders affecting adults. The reader is referred to other sources for the specialized topics on paediatric populations and post liver transplantation.

RECENT FINDINGS

Fibrosis stage at diagnosis is an independent predictor of liver transplant-free survival in patients with primary biliary cholangitis. Immunohistochemistry might have an important role in predicting response to treatment. New histological scoring systems with excellent correlation with long-term clinical outcomes are being developed in primary sclerosing cholangitis (PSC). Quantification of fibrosis with collagen proportionate area can improve risk stratification and could be particularly useful to assess treatment response in PSC.Gene sequencing on cytology and intrabiliary biopsy may improve risk stratification for cholangiocarcinoma. Genetic variants of ATP8B1, ABCB11 and ABCB4 are relatively common in adults with cholestatic liver disease. New causes of cholestatic liver injury have recently been described.

SUMMARY

Histology is often not necessary for the diagnosis of biliary disease, but can provide important information that may assist the clinician in patients' management. Histopathology remains crucial to confirm a diagnosis of cholangiocarcinoma, and to identify the pattern of biliary injury in immune-mediated cholangiopathies and rarer pathological entities.

ABC transporters: human disease and pharmacotherapeutic potential

Adenosine triphosphate (ATP)-binding cassette (ABC) transporters are a 48-member superfamily of membrane proteins that actively transport a variety of biological substrates across lipid membranes. Their functional diversity defines an expansive involvement in myriad aspects of human biology. At least 21 ABC transporters underlie rare monogenic disorders, with even more implicated in the predisposition to and symptomology of common and complex diseases. Such broad (patho)physiological relevance places this class of proteins at the intersection of disease causation and therapeutic potential, underlining them as promising targets for drug discovery, as exemplified by the transformative CFTR (ABCC7) modulator therapies for cystic fibrosis. This review will explore the growing relevance of ABC transporters to human disease and their potential as small-molecule drug targets.