Low-phospholipid-associated cholelithiasis syndrome: Prevalence, clinical features, and comorbidities

Primary intrahepatic lithiasis in western countries: role of ultrasound and comparison with MRI with MRCP

OBJECTIVES

To study hepatobiliary expert ultrasound (US) in a cohort of suspected primary intrahepatic lithiasis (IHL) and to compare these findings with MRI/MRCP data.

METHODS

All patients with a diagnosis of primary-IHL based upon biological and, or, clinical symptoms who underwent US between 2008 and 2023 were retrospectively enrolled in two tertiary hepatobiliary centers. Clinical characteristics, available genetic and radiological features (expert US and MRCP) were recorded. Data were compared for the presence of comet-tail images or stones on US, between US and MRCP features and between imaging and patients' genetic status. Statistical analyses were performed with R software environment version 4.2.1, by univariate and multivariate analysis.

RESULTS

A total of 112 primary-IHL patients were included (mean age 43 years old ±14 and 55% women). US identified primary-IHL in 92/112 (82%) patients including intrahepatic biliary comet-tail in 82/112 (73%) and stones in 51/112 (46%). Among these, 66/112 (68%) had both US and MRCP. Lithiasis was identified in 60/76 US (79%) and 44/76 MRCP (58%). MRCP showed only stones in 22/76, 29%. Genetic testing was performed in 66/112 (58%) patients. Thirty-two (49%) of these patients had pathogenic ABCB4/MDR3 gene variants, 14/66 (21%) other pathogenic variants and 5/66 (5%) had unknown significant variants. No genetic abnormalities were found in 19/66 (29%). A multivariate logistic model with the comet-tail sign as an outcome showed that there was a significant negative correlation between other pathogenic genetic variants and the comet-tail phenotype (P-value = 0.049).

CONCLUSION

US, and not MRCP, should be the primary diagnostic tool in suspected primary-IHL patients.

The RaDiCo information system for rare disease cohorts

BACKGROUND

Rare diseases (RDs) clinical care and research face several challenges. Patients are dispersed over large geographic areas, their number per disease is limited, just like the number of researchers involved. Current databases as well as biological collections, when existing, are generally local, of modest size, incomplete, of uneven quality, heterogeneous in format and content, and rarely accessible or standardised to support interoperability. Most disease phenotypes are complex corresponding to multi-systemic conditions, with insufficient interdisciplinary cooperation. Thus emerged the need to generate, within a coordinated, mutualised, secure and interoperable framework, high-quality data from national or international RD cohorts, based on deep phenotyping, including molecular analysis data, notably genotypic. The RaDiCo program objective was to create, under the umbrella of Inserm, a national operational platform dedicated to the development of RD e-cohorts. Its Information System (IS) is presented here.

MATERIAL AND METHODS

Constructed on the cloud computing principle, the RaDiCo platform was designed to promote mutualization and factorization of processes and services, for both clinical epidemiology support and IS. RaDiCo IS is based on an interoperability framework combining a unique RD identifier, data standardisation, FAIR principles, data exchange flows/processes and data security principles compliant with the European GDPR.

RESULTS

RaDiCo IS favours a secure, open-source web application in order to implement and manage online databases and give patients themselves the opportunity to collect their data. It ensures a continuous monitoring of data quality and consistency over time. RaDiCo IS proved to be efficient, currently hosting 13 e-cohorts, covering 67 distinct RDs. As of April 2024, 8063 patients were recruited from 180 specialised RD sites spread across the national territory.

DISCUSSION

The RaDiCo operational platform is equivalent to a national infrastructure. Its IS enables RD e-cohorts to be developed on a shared platform with no limit on size or number. Compliant with the GDPR, it is compatible with the French National Health Data Hub and can be extended to the RDs European Reference Networks (ERNs).

CONCLUSION

RaDiCo provides a robust IS, compatible with the French Data Hub and RDs ERNs, integrated on a RD platform that enables e-cohorts creation, monitoring and analysis.

A family with gallstone disease: defining inherited risk in the era of clinical genetic testing

Gallstones are among the most frequent hepatobiliary conditions. Although in most cases, they remain asymptomatic, they can cause complications and, in such cases, invasive treatments like endoscopic retrograde cholangiography (ERC) or cholecystectomy are required. Here, we present the results of genetic testing of a single family with a high incidence of symptomatic gallstones and cholestatic liver phenotypes. Gallstone disease was detected among seven family members spanning three generations, and DNA samples were available from five of them. Genotyping was performed using TaqMan assays for known, selected genetic risk factors for gallstones and cholestasis, as well as next generation sequencing (NGS) of three genes involved in hepatobiliary transport. In all genotyped patients, we detected at least one copy of the gallstone-predisposing p.D19H variant in the hepatobiliary sterol transporter ABCG5/8, and in three cases, this variant was found in the rare homozygous state. In addition, the patients were all homozygous carriers of two intronic variants (c.2211+16C >T and c.3508-16T>C) and two common polymorphisms (c.504C>T and c.711A>T) in the ABCB4 gene, as well as the ATP8B1 gene variant c.696T>C. All genotyped patients also carried the predisposing variants c.1331C>T and c.3084A>G of the hepatobiliary bile salt export pump ABCB11 in either heterozygous or homozygous form. Hence, we propose that these variants taken together may have contributed to the high frequency of gallstone disease in this family, although functional studies for some variants are still lacking. In this report, we present these findings and discuss the challenges associated with interpreting sequencing data.

Current approach to diagnosis and management of low-phospholipid associated cholelithiasis syndrome

PURPOSE OF REVIEW

Low phospholipid-associated cholelithiasis (LPAC) syndrome is a rare genetic form of intrahepatic cholesterol lithiasis, affecting mainly young adults. This review describes the recent advances in genetic and clinical characterization, diagnosis and management of LPAC syndrome.

RECENT FINDINGS

Recent publications report data from several retrospective cohorts. These cohorts describe the main clinical features, the most frequent radiological lesions, complications, the results of biliary endoscopic procedures and the prognosis associated with LPAC syndrome.

SUMMARY

LPAC syndrome has been linked to a partial defect in the ATP binding cassette subfamily B member 4 ( ABCB4 ) gene encoding the canalicular phospholipid transporter multidrug resistance protein 3, but this mechanism would explain only half the cases, or even fewer. This syndrome is characterized by the appearance of cholelithiasis at an abnormally early age (before 40) and by the persistence of biliary symptoms after cholecystectomy. The diagnosis is usually confirmed by an ultrasound scan of the liver, which reveals the presence of intrahepatic microlithiasis, as evidenced by comet-tail images or microspots along the intrahepatic bile ducts. Ursodeoxycholic acid, at a daily dose of 5-15 mg/kg, is the reference treatment. If not performed prior to diagnosis, cholecystectomy should be avoided wherever possible. In complicated or refractory forms, endoscopic biliary intervention may be necessary.

Genetics of Gallstones

Gallstone disease (GSD) is a common gastrointestinal disorder affecting approximately 10-20% of the global adult population, characterized by the presence of gallstones, predominantly cholesterol-based, in the gallbladder and/or biliary ducts. While many patients remain asymptomatic, more than 20% develop clinical symptoms such as abdominal pain, nausea, vomiting, jaundice, and anorexia, potentially leading to severe complications like acute cholecystitis and biliary pancreatitis. GSD has a significant genetic predisposition, with the variable prevalence of the disease according to ethnicity being highest in American and European countries and lowest in Asian and African populations. Numerous genes encoding membrane transporters involved in bile metabolism are associated with GSD, including in particular members of ATP-binding cassette transporters and others, which affect bile lithogenicity and contribute to the development of gallstones. Specific mutations in these genes are linked to an increased risk of gallstone formation, especially in individuals with certain hereditary conditions such as hemolytic diseases, thyroid disorders, and hyperparathyroidism. Advances in genetic studies have identified new variants that influence the risk of cholelithiasis, although the exact mechanisms remain partially understood in many cases. This review briefly summarizes the genetic causes of cholelithiasis, highlighting various pathogenetic mechanisms. It presents the currently used treatments and the potential implications of widely applied genetic diagnostics.

Genotypes and different clinical variants between children and adults in progressive familial intrahepatic cholestasis: a state-of-the-art review

INTRODUCTION

Progressive Familial intrahepatic cholestasis (PFIC) are rare disorders of bile acid (BAs) secretion and transport with a genetic background. PFIC are paediatric manifestations, but the same variants causing PFIC can also cause cholestasis with a later paediatric onset or adult-onset cholestatic disease (AOCD). Pruritus is a symptom of cholestasis that can be so devastating that it requires a liver transplant (LT) in children; some PFIC types have been described as at risk of liver cancer development. Commonly prescribed medications for PFIC symptoms can partially relieve pruritus without changing the natural history of the disease. Recently, a therapy reducing the intestinal resorption of BAs has been approved; it is effective on both pruritus and cholestasis in PFIC, potentially being a disease-modifying intervention.

AREAS COVERED

The clinical and genetic characteristics of different PFIC and AOCD are summarized to provide a common background for geneticists and paediatric and adult hepatologists in diagnosis and management.

EXPERT OPINION

Collaboration between paediatric and adult hepatologists and geneticists will become crucial for cholestatic disease research and patient treatment. Therefore, adult hepatologists will need to learn more about FIC. This might enable the implementation of individualized surveillance in FIC patients and the evaluation of patient family histories.

Hepatolithiasis pathogenesis update

Hepatolithiasis is prevalent in East Asian countries and not common in Western countries. In recent years, because of the increased number of immigrants from East Asia in Western countries, hepatolithiasis has gradually become a global problem. Although current surgical interventions for hepatolithiasis boast a high rate of stone clearance, the persistent challenges of the disease's refractory nature and high recurrence rate continue to complicate its treatment. Therefore, understanding its underlying pathogenesis is meaningful for effective treatment. In this review, we discuss the common risk factors: infection, cholangitis, environmental factors and diet habits, abnormal bile components, anatomical abnormalities, and bile stasis, and summarize the relevant mechanisms.

Relationship between Abnormal Lipid Metabolism and Gallstone Formation

Cholelithiasis is a common biliary system disease with a high incidence worldwide. Abnormal lipid metabolism has been shown to play a key role in the mechanism of gallstones. Therefore, recent research literature on the genes, proteins, and molecular substances involved in lipid metabolism during the pathogenesis of gallstones has been conducted. This study aimed to determine the role of lipid metabolism in the pathogenesis of gallstones and provide insights for future studies using previous research in genomics, metabolomics, transcriptomics, and other fields.

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

Additional genetic variants associated with the progressive familial intrahepatic cholestasis (PFIC) phenotype and new genetic cholangiopathies, with an emerging role of ciliopathy genes, are increasingly being identified. 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.

Low phospholipid-associated cholelithiasis syndrome, a not uncommon cause of biliary problems and hospital admissions

BACKGROUND AND AIMS

biliary diseases are a major cause of morbidity and mortality for patients and a burden for the healthcare system. The genetic syndrome of low phospholipid-associated cholelithiasis (LPAC) is a little known and rare entity whose treatment with bile salts avoids symptoms, admissions and the need for surgery. The aim of this study was to determine its incidence and characteristics in our center.

METHODS

prospective study performed between February 2021 and September 2022. LPAC was diagnosed if at least two of the following were present: onset of biliary problems < 40 years of age, recurrence of symptoms after cholecystectomy, ultrasound image of hepatolithiasis (multiple echoic foci, comet-tail images, hepatolithiasis with acoustic shadow). Demographic, clinical, genetic (analysis of MDR3 gene mutations) and ultrasound characteristics and their incidence were analyzed in hospital admissions for biliary causes.

RESULTS

thirty-six patients with LPAC were identified. Of these, six were among 237 admissions due to biliary causes in the previous nine months, with an incidence of 2.5 % (95 % CI: 1.17-5.41). By age subgroup, the incidence was 16.7 % in those admitted < 40 years of age and 9.1 % in those < 50. Considering females only, the incidence was 21 % in those admitted < 40 years and 15.8 % in those < 50 years. All patients remained asymptomatic after treatment with ursodeoxycholic acid and there were no new admissions.

CONCLUSIONS

LPAC syndrome is not as uncommon as it may appear, especially in women < 50 years of age admitted with biliary problems. Its correct diagnosis based on simple criteria could avoid a significant number of hospital admissions and unnecessary cholecystectomies.

Searching for low phospholipid associated cholelithiasis among patients with post-cholecystectomy biliary pain

INTRODUCTION

Low phospholipid associated cholelithiasis (LPAC) is associated with variants of the adenosine triphosphate-binding cassette subfamily B, member 4 (ABCB4) gene and is characterized by reduced phosphatidylcholine secretion into bile, impairing the formation of micelles and thus exposing bile ducts to toxic bile acids and increasing cholesterol saturation. LPAC is present in 1% of patients with gallstones and post-cholecystectomy pain is common in this group. LPAC is an under-appreciated cause of post-cholecystectomy pain. The aim of this study is to assess a cohort of patients with post-cholecystectomy pain to identify those with clinical features suggesting that further investigations for LPAC would be beneficial.

METHODS

A retrospective chart review was performed of the first 2 years of post-operative follow-up for all patients under 40 years of age undergoing cholecystectomy for symptomatic gallstones at a tertiary centre between January 2016 and December 2017.

RESULTS

258 patients under the age of 40 underwent a cholecystectomy. 50 patients (19.4%) reported abdominal pain post-cholecystectomy. Five patients (1.9%) fulfilled the criteria for suspected LPAC. Family history of gallstones was documented in 33 of 258 (12.8%) of cases. Obstetric history was obtained in 69 of 197 (35%) female patients. None of the five patients identified above who satisfied the criteria of LPAC had the diagnosis of LPAC considered by their treating clinicians.

CONCLUSION

LPAC is an under-recognized cause of post-cholecystectomy pain. Treatment can avoid long-term symptoms and complications. Clinicians should take a family history and obstetric history to alert them to the diagnosis of LPAC.

Endoscopic features of low-phospholipid-associated cholelithiasis syndrome: A retrospective cohort study

BACKGROUND AND OBJECTIVE

LPAC (low phospholipid-associated cholelithiasis) syndrome is a rare genetic form of cholelithiasis. ERCP (endoscopic retrograde cholangiopancreatography) is often used to remove gallstones in the bile duct. No published data is available on the role of ERCP in LPAC syndrome.

PATIENTS AND METHODS

In this retrospective cohort study, we included patients diagnosed with LPAC syndrome in a single tertiary referral center between 2009 and 2021. Our aim was to assess the frequency, indications, modalities, results, and complications of ERCP, as well as predictive factors for ERCP, in LPAC syndrome. Independent factors associated with ERCP occurrence were identified using a multivariable Cox regression analysis.

RESULTS

ERCP was required in 31.2 % of the 269 patients included for analysis. Among patients who required ERCPs, 78.6 % had the procedure before diagnosis (i.e., starting UDCA). Most common indications were choledocholithiasis (53.6 %) and acute cholangitis (29.5 %). Post ERCP pancreatitis, perforation and bleeding rates were 7.2 %, 2.6 %, and 1.3 %, respectively. Age and history of cholelithiasis in first-degree relatives were associated with a higher risk of ERCP (Hazard-ratio [HR]=1.30 [95 %confidence-interval [CI] 1.04-1.62] and HR=1.88 [95 %CI 1.15-3.07] respectively). Female gender and UDCA intake ≥ 1 year were associated with a lower risk of ERCP (HR=0.49 [95 %CI 0.29-0.82] and HR=0.44 [95 %CI 0.22-0.90] respectively). Median follow-up was 10.8 years.

CONCLUSION

One-third of patients with LPAC syndrome undergo sphincterotomy. However, most procedures are performed before diagnosis and UDCA is associated with a lower risk of endoscopic procedure. Earlier diagnosis and treatment with UDCA may further reduce the need for ERCP in patients with LPAC syndrome.

Liver imaging and pregnancy: what to expect when your patient is expecting

Liver diseases in pregnancy can be specific to gestation or only coincidental. In the latter case, the diagnosis can be difficult. Rapid diagnosis of maternal-fetal emergencies and situations requiring specialized interventions are crucial to preserve the maternal liver and guarantee materno-fetal survival. While detailed questioning of the patient and a clinical examination are highly important, imaging is often essential to reach a diagnosis of these liver diseases and lesions. Three groups of liver diseases may be observed during pregnancy: (1) diseases related to pregnancy: intrahepatic cholestasis of pregnancy, pre-eclampsia, eclampsia, hemolysis, elevated liver enzymes and low platelets (HELLP) syndrome, and acute fatty liver of pregnancy; (2) liver diseases that are more frequent during or exacerbated by pregnancy: acute herpes simplex hepatitis, Budd-Chiari syndrome, hemorrhagic hereditary telangiectasia, hepatocellular adenoma, portal vein thrombosis, and cholelithiasis; (3) coincidental conditions, including acute hepatitis, incidental focal liver lesions, metabolic dysfunction-associated steatotic liver disease, cirrhosis, hepatocellular carcinoma, liver abscesses and parasitosis, and liver transplantation. Specific knowledge of the main imaging findings is required to reach an early diagnosis, for adequate follow-up, and to avoid adverse consequences in both the mother and the fetus.Critical relevance statement Pregnancy-related liver diseases are the most important cause of liver dysfunction in pregnant patients and, in pregnancy, even common liver conditions can have an unexpected turn. Fear of radiations should never delay necessary imaging studies in pregnancy.Key points• Pregnancy-related liver diseases are the most frequent cause of liver dysfunction during gestation.• Fear of radiation should never delay necessary imaging studies.• Liver imaging is important to assess liver emergencies and for the diagnosis and follow-up of any other liver diseases.• Common liver conditions and lesions may take an unexpected turn during pregnancy.• Pregnancy-specific diseases such as pre-eclampsia and HELLP syndrome must be rapidly identified. However, imaging should never delay delivery when it is considered to be urgent for maternal-fetal survival.

Obeticholic acid as a second-line treatment for low phospholipid-associated cholelithiasis syndrome

BACKGROUND

Low phospholipid-associated cholelithiasis (LPAC) syndrome is a rare genetic cause of hepatolithiasis. A pathogenic variant of the ABCB4 gene is reported in half of all patients. Ursodeoxycholic acid (UDCA) is the only drug approved. However, in some patients, UDCA fails to prevent recurrence of symptoms and complications. Experimental evidence suggests that agonists of the farnesoid-X receptor (FXR), the main transcription factor regulating ABCB4, may be beneficial in this context.

AIM

To study the efficacy of obeticholic acid (OCA) in patients with LPAC syndrome with an inadequate response or intolerance to UDCA.

METHODS

This was a retrospective study of patients with LPAC syndrome treated with OCA, a selective FXR agonist.

RESULTS

We reviewed the records of five OCA-treated patients (4 women; median age 29; ABCB4 variant in 4; no hepatic fibrosis). All patients received OCA at an initial dose of 5 mg daily and then 10 mg daily for a median period of 36 months in combination with UDCA (4 patients) or as a monotherapy (one patient). There were no adverse effects reported. Four patients had improvement in their symptoms - three completely and one partially. One patient had no clinical benefit. Abnormalities of blood liver tests persisted in one patient despite resolution of symptoms. Radiological signs of hepatolithiasis persisted in three of the four patients who responded clinically to OCA.

CONCLUSIONS

These preliminary observations suggest that OCA may have the potential to effectively treat LPAC syndrome in patients with inadequate response or intolerance to UDCA. Larger studies are needed to confirm these data.

Considerations for Low Phospholipid-Associated Cholelithiasis (LPAC) Syndrome: Report of Three Cases

Low phospholipid-associated cholelithiasis (LPAC) syndrome is a rare underdiagnosed genetic feature presenting less than 1% of symptomatic cholelithiasis, with variable clinical forms ranging from simple to complications. Diagnosis criteria are recurrent biliary symptomatology occurring in young patients (<40 years old) and/or recurrence after cholecystectomy and/or having a history of biliary gallstones in first-degree relatives and characteristic ultrasound findings. Early detection of this entity, due to the awareness of gastroenterologists, radiologists, and visceral surgeons, will allow an improvement in the quality of life of patients and the prevention of complications. We report three cases of the LPAC syndrome and discuss its different aspects.

Genetic alterations and molecular mechanisms underlying hereditary intrahepatic cholestasis

Hereditary cholestatic liver disease caused by a class of autosomal gene mutations results in jaundice, which involves the abnormality of the synthesis, secretion, and other disorders of bile acids metabolism. Due to the existence of a variety of gene mutations, the clinical manifestations of children are also diverse. There is no unified standard for diagnosis and single detection method, which seriously hinders the development of clinical treatment. Therefore, the mutated genes of hereditary intrahepatic cholestasis were systematically described in this review.

Imaging of the biliary tract

PURPOSE OF REVIEW

Magnetic resonance cholangiopancreatography (MRCP) has become the reference examination for the exploration of the biliary tract and has replaced endoscopic cholangiography for the analysis of the biliary tract because of its equivalent performance and its noninvasive character.

RECENT FINDINGS

Based on the International Primary Sclerosing Cholangitis (PSC) Study Group recommendations for MR imaging in PSC, two protocols can be distinguished for the imaging of biliary tract: a basic protocol and a more complete protocol. It is essential to know the main pitfalls in order not to wrongly describe biliary anomalies. In addition to the excellent performance of MR imaging with MRCP in analyzing the anatomy and the anomalies of the biliary tree, complementary techniques have recently been developed. Several MR prognostic factors have been described. New hepato-specific contrast agents are now available for assessment of the general and segmental liver function. MR Elastography and Diffusion-weighted MR sequences are accurate to evaluate the degree of hepatic fibrosis. Finally, images obtained in MRCP can be postprocessed by a software that will analyze and model the biliary tree in order to quantitatively evaluate the biliary system.

SUMMARY

Magnetic resonance imaging with its recent developments becomes by now an essential tool for the evaluation of biliary diseases.

Targeted liver ultrasound performed by an expert is the pivotal imaging examination for low phospholipid-associated cholelithiasis

OBJECTIVES

Low phospholipid-associatedcholelithiasis (LPAC) is a clinical syndrome that can be associated with variants in the adenosinetriphosphate-binding cassette subfamily B, member 4 (ABCB4) transporter gene, in a proportion of patients. The diagnosis of LPAC is defined by clinical as well as imaging criteria of intrahepatic hyperechoic foci or microlithiasis and biliary sludge on ultrasound. The aim of the study was to assess the role of imaging in investigating patients presenting with clinical features suggesting a diagnosis of LPAC.

METHODS

Imaging findings in 51 patients with clinical LPAC were retrospectively reviewed. Most patients had been referred with difficult-to-manage biliary pain postcholecystectomy and some with intrahepatic dilated ducts and stones. The diagnosis of LPAC was made on clinical features.

RESULTS

The patients were young with symptom onset at median age 24 years and were mainly female (75%). Ultrasound was performed by an expert in 48/51 and magnetic resonance cholangiopancreatography (MRCP) in 47/51 patients. Targeted liver ultrasound found small hyperechoic foci with comet tail artifacts or posterior acoustic shadowing typical of LPAC in 30/48 (63%) of examinations. However, ultrasound examinations performed before referral for investigation did not report these findings. Intrahepatic duct dilatation was seen in 26/51 (51%) of cases. MRCP did not reliably detect microlithiasis.

CONCLUSIONS

Targeted liver ultrasound performed by an expert aware of the possible diagnosis is the pivotal investigation for patients with clinical features suggesting LPAC. The findings in ultrasound performed before referral suggest LPAC is under-recognized and under-diagnosed.

The Etiology of Cholelithiasis in Children and Adolescents-A Literature Review

The incidence of gallstone disease has increased in recent years. The pathogenesis of cholelithiasis is not fully understood. The occurrence of the disease is influenced by both genetic and environmental factors. This article reviews the literature on cholelithiasis in children, with the exception of articles on hematological causes of cholelithiasis and cholelithiasis surgery. The aim of this review is to present the latest research on the pathogenesis of gallstone disease in children. The paper discusses the influence of all factors known so far, such as genetic predisposition, age, infections, medications used, parenteral nutrition, and comorbidities, on the development of gallstone disease. The course of cholelithiasis in the pediatric population is complex, ranging from asymptomatic to life-threatening. Understanding the course of the disease and predisposing factors can result in a faster diagnosis of the disease and administration of appropriate treatment.

Gallstones: The thing in itself

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Vasor: Accurate prediction of variant effects for amino acid substitutions in multidrug resistance protein 3

The phosphatidylcholine floppase multidrug resistance protein 3 (MDR3) is an essential hepatobiliary transport protein. MDR3 dysfunction is associated with various liver diseases, ranging from severe progressive familial intrahepatic cholestasis to transient forms of intrahepatic cholestasis of pregnancy and familial gallstone disease. Single amino acid substitutions are often found as causative of dysfunction, but identifying the substitution effect in in vitro studies is time and cost intensive. We developed variant assessor of MDR3 (Vasor), a machine learning-based model to classify novel MDR3 missense variants into the categories benign or pathogenic. Vasor was trained on the largest data set to date that is specific for benign and pathogenic variants of MDR3 and uses general predictors, namely Evolutionary Models of Variant Effects (EVE), EVmutation, PolyPhen-2, I-Mutant2.0, MUpro, MAESTRO, and PON-P2 along with other variant properties, such as half-sphere exposure and posttranslational modification site, as input. Vasor consistently outperformed the integrated general predictors and the external prediction tool MutPred2, leading to the current best prediction performance for MDR3 single-site missense variants (on an external test set: F1-score, 0.90; Matthew's correlation coefficient, 0.80). Furthermore, Vasor predictions cover the entire sequence space of MDR3. Vasor is accessible as a webserver at https://cpclab.uni-duesseldorf.de/mdr3_predictor/ for users to rapidly obtain prediction results and a visualization of the substitution site within the MDR3 structure. The MDR3-specific prediction tool Vasor can provide reliable predictions of single-site amino acid substitutions, giving users a fast way to initially assess whether a variant is benign or pathogenic.

Low phospholipids associated cholelithiasis syndrome in a young women: A rare case report

Low phospholipid-associated cholelithiasis (LPAC) is a rare, still poorly understood genetic disorder characterized by the association of an ABCB4 mutation and low biliary phospholipid concentration with recurrent cholelithiasis, responsible for the development of intrahepatic lithiasis in adults. The mutation of the ABCB4 gene, which codes for the ABCB4/MDR3 ductal protein, a biliary transporter, leads to precipitation of cholesterol crystals in the bile ducts leading to the formation of intrahepatic stones. The diagnosis should be suspected when at least 2 of the following criteria are present: onset of symptoms before age 40; recurrence of biliary symptoms (biliary colic, jaundice, cholangitis, acute pancreatitis) after cholecystectomy; presence of echogenic foci in the liver indicative of intrahepatic stones or biliary sludge; previous episode(s) of intrahepatic cholestasis during pregnancy; and a family history of gallstones in first degree relatives. Imaging techniques, especially ultrasound, play an important role in the detection of intrahepatic stones. The majority of clinical situations are simple and not serious, often managed by medical treatment with ursodeoxycholic acid, but certain complicated forms may require more invasive endoscopic or surgical treatment. We report a case of a 43-year-old woman, cholecystectomized 5 years ago, who presented with liver colic-like pain with cytolysis and biological cholestasis. Ultrasound and MRI showed the presence of intrahepatic calculi disseminated along the bile duct pathway creating a comet tail appearance and generating a posterior shadow cone. The interrogation of the patient showed that her sister was being followed for LPAC syndrome. The diagnosis of LPAC syndrome was retained and the patient was put under medical treatment with ursodeoxycholic acid with regular clinical, biological and radiological follow-up.

Clinical, biological, radiological, and genetic study of LPAC syndrome in Tunisian patients

BACKGROUND AND STUDY AIMS

Low phospholipid-associated cholelithiasis (LPAC) syndrome is a form of cholelithiasis associated with the ABCB4 gene mutation. The defects of the protein ABCB4 encoded by this gene promote the formation of biliary cholesterol microcalculations. ABCB4 screening is negative in a significant proportion of patients.

PATIENTS AND METHODS

An analytical study of the epidemiological, clinical, biological, and radiological characteristics of 19 patients was conducted, followed by Sanger-type sequencing of the 27 exons encoding the ABCB4 gene.

RESULTS

Our results showed a female predominance, symptomatic vesicular lithiasis predominance, and a high frequency of biliary complications in patients carrying an ABCB4 mutation. Normal ​​ liver enzyme values were found in 84.2% of the cases. Intrahepatic hyperechoic foci were present in 68.4%. Molecular analysis detected a pathogenic mutation of the ABCB4 gene in 31.57% of patients. The mutations found were a nonsense mutation and three missense mutations, including two new mutations.

CONCLUSION

Our epidemiological, clinical, and genetic results concord with previous studies of LPAC syndrome. Two of the mutations we found have never been detected in patients with LPAC. The low percentage of ABCB4 gene mutations can be explained by the absence of studies of other genes involved in bile acid homeostasis besides the ABCB4 gene and by the inclusion criteria used in this study.

Cholestatic liver diseases of genetic etiology: Advances and controversies

With the application of modern investigative technologies, cholestatic liver diseases of genetic etiology are increasingly identified as the root cause of previously designated "idiopathic" adult and pediatric liver diseases. Here, we review advances in the field enhanced by a deeper understanding of the phenotypes associated with specific gene defects that lead to cholestatic liver diseases. There are evolving areas for clinicians in the current era specifically regarding the role for biopsy and opportunities for a "sequencing first" approach. Risk stratification based on the severity of the genetic defect holds promise to guide the decision to pursue primary liver transplantation versus medical therapy or nontransplant surgery, as well as early screening for HCC. In the present era, the expanding toolbox of recently approved therapies for hepatologists has real potential to help many of our patients with genetic causes of cholestasis. In addition, there are promising agents under study in the pipeline. Relevant to the current era, there are still gaps in knowledge of causation and pathogenesis and lack of fully accepted biomarkers of disease progression and pruritus. We discuss strategies to overcome the challenges of genotype-phenotype correlation and draw attention to the extrahepatic manifestations of these diseases. Finally, with attention to identifying causes and treatments of genetic cholestatic disorders, we anticipate a vibrant future of this dynamic field which builds upon current and future therapies, real-world evaluations of individual and combined therapeutics, and the potential incorporation of effective gene editing and gene additive technologies.

Targeted-Capture Next-Generation Sequencing in Diagnosis Approach of Pediatric Cholestasis

Background: Cholestasis is a frequent and severe condition during childhood. Genetic cholestatic diseases represent up to 25% of pediatric cholestasis. Molecular analysis by targeted-capture next generation sequencing (NGS) has recently emerged as an efficient diagnostic tool. The objective of this study is to evaluate the use of NGS in children with cholestasis. Methods: Children presenting cholestasis were included between 2015 and 2020. Molecular sequencing was performed by targeted capture of a panel of 34 genes involved in cholestasis and jaundice. Patients were classified into three categories: certain diagnosis; suggested diagnosis (when genotype was consistent with phenotype for conditions without any available OMIM or ORPHANET-number); uncertain diagnosis (when clinical and para-clinical findings were not consistent enough with molecular findings). Results: A certain diagnosis was established in 169 patients among the 602 included (28.1%). Molecular studies led to a suggested diagnosis in 40 patients (6.6%) and to an uncertain diagnosis in 21 patients (3.5%). In 372 children (61.7%), no molecular defect was identified. Conclusions: NGS is a useful diagnostic tool in pediatric cholestasis, providing a certain diagnosis in 28.1% of the patients included in this study. In the remaining patients, especially those with variants of uncertain significance, the imputability of the variants requires further investigations.

Low Phospholipid-Associated Cholelithiasis: Contribution of Imaging in Two Cases

Low phospholipid-associated cholelithiasis (LPAC) is a genetic disease responsible for the development of intrahepatic lithiasis. It is retained in the presence of two of the following three criteria: age of onset of biliary symptoms less than 40 years; echogenic intrahepatic images or microlithiasis; and the recurrence of biliary clinical signs after cholecystectomy. The majority of clinical situations are simple and not serious, but some complicated forms may require more invasive endoscopic or surgical treatments. By presenting two case studies, we illustrated and summarized the different aspects of this entity.