Low Phospholipid-associated Cholelithiasis Research Articles

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

Background and objectiveLPAC (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 methodsIn 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. ResultsERCP 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. ConclusionOne-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.

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

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. 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. 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. 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.

Tetraparesis following thoracic spine surgery in a patient with Klippel–Feil syndrome and ABCB4 mutation: a case report

BackgroundKlippel–Feil syndrome is a rare condition described in 1912 by Maurice Klippel and André Feil. It is defined as a congenital cervical fusion of at least two vertebrae, associated with a classical triad of clinical signs: short neck, low posterior hairline, and limited range of movement. However, Klippel–Feil syndrome manifests with a vast spectrum of phenotypes, ranging from no symptoms to complete triad, with or without other associated malformations. Most commonly, CCF results from sporadic mutations, even though autosomal recessive, autosomal dominant, or even X-linked inheritance can be detected. The ATP-binding cassette subfamily B member 4 is only expressed in the liver and is involved in biliary phospholipid secretion. The clinical spectrum includes various hepatobiliary pathologies, including low phospholipid-associated cholelithiasis, and has never been associated with musculoskeletal anomalies.Case presentationA 55-year-old male Caucasian patient presenting with low phospholipid-associated cholelithiasis syndrome with ATP-binding cassette subfamily B member 4 mutation and liver cirrhosis was referred to our clinic for a liver transplant. A period of 6 months before, the patient underwent a T7–T9 posterior fixation for a T8 osteoporotic fracture. Postoperatively, he was tetraparetic, whereas he was neurologically intact before the operation. At admission to our hospital, he was still tetraparetic and presented with clinical signs of cervical myelopathy. Moreover, he suffered a limitation of cervical range of motion in all directions, short neck, and low posterior hairline. Imaging showed multiple cervical and thoracic vertebral bodies fusion, as well as cervical spine stenosis. Based on the available data, we diagnosed a type 3 Klippel–Feil syndrome according to Samartzis’ classification.ConclusionsThe heterogeneity of KFS and the various potential hereditary links that are known indicate that it is important to highlight all potential cases related to known genetic defects. At present, no association between ATP-binding cassette subfamily B member 4 mutation and congenital cervical fusions has been reported. The other important clinical focus of this case is the appearance of spontaneous tetraparesis after thoracic spine surgery. This mechanism remains unclear, but considering different spinal anatomy it might have been due to difficult intubation and patient’s positioning during his previous operation.

Low phospholipid-associated cholelithiasis (LPAC) syndrome is not an uncommon cause of biliary problems and hospital admissions

Low phospholipid-associated cholelithiasis (LPAC) syndrome is not an uncommon cause of biliary problems and hospital admissions

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

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. To study the efficacy of obeticholic acid (OCA) in patients with LPAC syndrome with an inadequate response or intolerance to UDCA. This was a retrospective study of patients with LPAC syndrome treated with OCA, a selective FXR agonist. 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. 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.

Diagnostic workup of suspected hereditary cholestasis in adults: a case report

Hereditary cholestasis comprises a broad spectrum of clinical phenotypes of varying severity. Severe forms such as progressive familial intrahepatic cholestasis (PFIC) mostly affect children with disease onset within their first years. Nevertheless, late-onset PFIC forms are increasingly diagnosed. Most adults present with less severe forms of hereditary cholestasis, often suffering from pruritus, gallstone disease, jaundice, or elevated liver enzymes. To identify the underlying genetic background and to rule out potential differential diagnoses, a broad genetic analysis like whole exome sequencing (WES) is recommended. Knowledge of the affected gene may have an impact not only on patient surveillance due to risk for disease progression or tumor development but also on potential therapeutic strategies. This case of the adult patient illustrates the importance of broad genetic analysis, which brought up the potentially relevant rare multidrug resistance protein 3 (MDR3) missense variant p.(Asn489Tyr) underlying the patient’s clinical phenotype of low phospholipid-associated cholelithiasis (LPAC). Patients with MDR3 disease may have an increased risk for cholangiocarcinoma (CCA) development and therefore need an individualized surveillance strategy. Most MDR3-affected patients benefit from life-long therapy with ursodeoxycholic acid (UDCA), which is well tolerated. Bezafibrate treatment can reduce pruritus, one of the main symptoms affecting the quality of life. Whether the administration of ileal bile acid transporter (IBAT) inhibitors is beneficial in adult patients with MDR3 disease is so far unknown.

Low-phospholipid associated cholelithiasis (LPAC) syndrome: an unusual form in an elderly and overweight woman

BackgroundLow-phospholipid associated cholelithiasis (LPAC) remains an under-diagnosed condition. It can be revealed by complications such as acute cholecystitis, acute angiocholitis and acute pancreatitis. We report a case of acute pancreatitis secondary to LPAC syndrome.Case presentationA 58-year-old woman was hospitalized for recurrent biliary-type abdominal pain after cholecystectomies. The diagnosis of acute biliary pancreatitis revealing a low-phospholipid associated cholelithiasis syndrome was retained after explorations. An abdominal ultrasound performed by an expert radiologist allowed us to confirm the diagnosis of LPAC syndrome, showing a comet tail image along the intrahepatic bile ducts. Ursodeoxycholic acid was started without waiting for the result of the ABCB4 mutation. The outcome was spectacular with complete disappearance of the symptoms after the first week.ConclusionExpert ultrasound remains the key examination for the confirmation of the diagnosis of a low-phospholipid associated cholelithiasis syndrome. It should be requested at the slightest warning signs such as a young age less than 40 years and recurrence of biliary symptoms after cholecystectomy.

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

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. 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. 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. 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.

ABCB4 variant is associated with hepatobiliary MR abnormalities in people with low-phospholipid-associated cholelithiasis syndrome

Background & AimsThe low-phospholipid-associated cholelithiasis (LPAC) syndrome is a recently described peculiar form of cholelithiasis associated with the ATP-binding-cassette subfamily B, member 4 (ABCB4) gene deficiency. The purpose of our study was to analyse the relationship between magnetic resonance (MR) features and the genetic status of ABCB4 in people with LPAC syndrome.MethodsA total of 233 individuals with proven LPAC syndrome were enrolled between January 2003 and June 2018 in a retrospective single-centre study. Inclusion criteria included availability of clinical files, MR images, and genetic data. MR images were analysed by consensus among 3 senior radiologists blinded to the status of ABCB4 gene mutation.ResultsA total of 125 individuals (mean age at first MR imaging 40.8 years; 66% females; 48% ABCB4 variant) were included. MR abnormalities were found in 61 (49%) of the 125 individuals. Forty (67%) of the 60 individuals with an ABCB4 gene variant had MR abnormalities as compared with 21 (33%) of the 65 individuals without an ABCB4 gene variant (odds ratio [OR] 4.1, 95% CI 1.9–9.5, p = 0.0001). Compared to individuals with no variant, individuals with an ABCB4 variant were more likely to show intrahepatic macrolithiasis (56 vs. 17%; OR 6.3, 95% CI 2.6–16.2, p <0.0001), bile duct dilatation (60 vs. 18%; OR 6.5, 95% CI 2.7–16.3, p <0.0001), and at least 1 MR feature of complication (35 vs. 15%; OR 2.9, 95% CI 1.1–7.8, p <0.05).ConclusionsABCB4-related LPAC syndrome is associated with more frequent and severe hepatobiliary MR abnormalities. This finding strongly supports the major role of the ABCB4 gene in the pathogenesis of LPAC syndrome and highlights a genotype–phenotype association in this inherited disease with genetic heterogeneity.Lay summaryABCB4-related LPAC syndrome associated with an ABCB4 gene variant demonstrates more frequent and severe hepatobiliary MR abnormalities. This finding supports the major role of the ABCB4 gene in the pathogenesis of LPAC syndrome.

Genetic Analysis of ABCB4 Mutations and Variants Related to the Pathogenesis and Pathophysiology of Low Phospholipid-Associated Cholelithiasis.

Clinical studies have revealed that the ABCB4 gene encodes the phospholipid transporter on the canalicular membrane of hepatocytes, and its mutations and variants are the genetic basis of low phospholipid-associated cholelithiasis (LPAC), a rare type of gallstone disease caused by a single-gene mutation or variation. The main features of LPAC include a reduction or deficiency of phospholipids in bile, symptomatic cholelithiasis at <40 years of age, intrahepatic sludge and microlithiasis, mild chronic cholestasis, a high cholesterol/phospholipid ratio in bile, and recurrence of biliary symptoms after cholecystectomy. Needle-like cholesterol crystals, putatively “anhydrous” cholesterol crystallization at low phospholipid concentrations in model and native bile, are characterized in ABCB4 knockout mice, a unique animal model for LPAC. Gallbladder bile with only trace amounts of phospholipids in these mice is supersaturated with cholesterol, with lipid composition plotting in the left two-phase zone of the ternary phase diagram, consistent with “anhydrous” cholesterol crystallization. In this review, we summarize the molecular biology and physiological functions of ABCB4 and comprehensively discuss the latest advances in the genetic analysis of ABCB4 mutations and variations and their roles in the pathogenesis and pathophysiology of LPAC in humans, based on the results from clinical studies and mouse experiments. To date, approximately 158 distinct LPAC-causing ABCB4 mutations and variants in humans have been reported in the literature, indicating that it is a monogenic risk factor for LPAC. The elucidation of the ABCB4 function in the liver, the identification of ABCB4 mutations and variants in LPAC patients, and the exploration of gene therapy for ABCB4 deficiency in animal models can help us to better understand the cellular, molecular, and genetic mechanisms underlying the onset of the disease, and will pave the way for early diagnosis and prevention of susceptible subjects and effective intervention for LPAC in patients.

P-82 URSODEOXYCHOLIC ACID AND/OR CIPROFIBRATE FOR TREATING PATIENTS WITH PRESUMPTIVE DIAGNOSIS OF LOW PHOSPHOLIPID CHOLELITHIASIS, A CLINICAL SPECTRUM OF PROGRESSIVE FAMILIAL INTRAHEPATIC CHOLESTASIS TYPE 3

Low Phospholipid-Associated Cholelithiasis (LPAC) is a clinical spectrum of Progressive Familial Intrahepatic Cholestasis type 3 (PFIC3), with mutations in the ABCB4 gene, reduced levels of phosphatidylcholine in bile, formation of cholesterol gallstones, damage of bile ducts epithelium and cholestasis. Ursodeoxycholic acid (UDCA) is effective and fibrates may also be used to activate PPAR - α receptor, inducing bile secretion of phosphatidylcholine. Retrospectively evaluate efficacy and safety of ciprofibrate in LPAC/PFIC3. Diagnosis of PFIC3 was confirmed by detection of mutations of ABCB4 gene. LPAC diagnosis was suggested by 2 out of 5 criteria: biliary symptoms before 40 years; recurrence after cholecystectomy; intrahepatic lithiasis; cholelithiasis in first‐degree relatives; intrahepatic cholestasis of pregnancy or contraceptive‐induced cholestasis. Enzymes, liver function and pruritus were analyzed after 3, 6 and 12 months of UDCA and after ciprofibrate 100mg/day using the Wilcoxon test. 27(93%) patients with clinical diagnosis of LPAC and 2 of PFIC3. 23 (79%) female with mean age at onset of symptoms of 26.7±13.6 years. 23(80%) had family history of biliary disease; 22(76%) cholelithiasis before 40 years; 7(24%) intrahepatic lithiasis. 22/29 (78%) received ciprofibrate after 4.5±4.9 months of UDCA use, in a mean dose of 13.1±2.2mg/kg/day. During UDCA there was a significant decrease in aminotransferases, alkaline phosphatase(AP) and gamma-glutamyltransferase(GGT) levels, without significant improvement in the liver function. After addition of fibrate, pruritus disappeared in all 7 patients, with significant improvement of AP, GGT and albumin in the third month. There was no significant renal dysfunction. Fibrate was discontinued in 8: 1 liver transplantation, 2 irregular use, 5 side effects. 27 patients are still in follow up. Ciprofibrate was beneficial to improve pruritus and laboratory tests in LPAC/PFIC3 after partial response with UDCA. Fibrate therapy was safe and well tolerated.

ABCB4 variants in adult patients with cholestatic disease are frequent and underdiagnosed

BackgroundHeterozygous ABCB4 variants are not routinely tested in adults with cholestasis because of their supposed rarity and high costs. MethodsNineteen adult patients presenting with unexplained cholestasis, and/or recurrent gallstones were included; genotyping was not done in five due to lack of health insurance approval. Resultsheterozygous ABCB4 variants were identified in seven patients, followed by cascade testing of 12 family members: one patient underwent liver transplantation at age 40 for end-stage liver disease; one had compensated cirrhosis; all symptomatic adults had gallstones, including four with low phospholipid-associated cholelithiasis; four had intrahepatic cholestasis of pregnancy; all children and one 54-year old female were asymptomatic. Genotype: Families A and C: c.2211G>A (p.Ala737=) combined with c.959C>T (p.Ser320Phe) in one subject; Family B: c.1130T>C (p.Ile377Thr); Family D: large deletion removing ABCB4 exons 1-4 plus ABCB1, RUNDC3B, SLC25A40, DBF4, ADAM22 exons 1-3; Family E: c.1565T>C (p.Phe522Ser) ; Family F: c.1356+2T>C combined with c.217C>G (p.Leu73Val). All patients responded to ursodeoxycholic acid. ConclusionsWe found ABCB4 variants in half of the adults with unexplained cholestasis and/or recurrent gallstones presenting at our center, suggesting that this condition is underdiagnosed and undertreated, with serious consequences not only for the patients and their families, but also in terms of healthcare costs.

Carriers of ABCB4 gene variants show a mild clinical course, but impaired quality of life and limited risk for cholangiocarcinoma.

Adenosine triphosphate-binding cassette subfamily B member 4 (ABCB4) deficiency may lead to progressive familial intrahepatic cholestasis type 3 (PFIC3), biliary cirrhosis, low phospholipid-associated cholelithiasis (LPAC), intrahepatic cholestasis of pregnancy (ICP), oral contraceptive-induced cholestasis (CIC) or may remain asymptomatic. The long-term course, quality of life and histology were investigated in ABCB4 deficiency. Adult carriers of ABCB4 gene variants from two regional academic centres were analysed by history taking, electronic patient files, physical examination, blood analysis, abdominal ultrasound (US) and liver elastography. Patients completed a 36-Item Short Form Health Survey (SF-36) for quality of life and a Visual Analogue Scale (VAS) for pruritus. Available liver specimens were re-classified according to the Nakanuma scoring system, so far validated for primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) only. Quality of life data were compared to published data of patients with PBC, PSC and the general population. Sixty-seven patients were identified, 64 (96%) were alive at the time of analysis and 62 (93%) were (at some time) treated with ursodeoxycholic acid (UDCA). Two patients died of cholangiocarcinoma (CCA), and one of decompensated biliary cirrhosis. Three additional deaths of CCA were reported in first-degree relatives. Transplant-free survival was 91% (median follow-up 14years). Liver stiffness was normal (<6.3kPa) in 75%, intrahepatic stones were detected at ultrasound (US) in 33% and microcalcifications in 22% of cases. Quality of life (n=48) was lower than in the general population particularly in energy/fatigue and general health domains and comparable to that in PSC. Staging according to Nakanuma in 15 specimens reflected the clinical course. ABCB4 deficiency has a mild clinical course, but impaired quality of life and limited risk of CCA. The Nakanuma scoring system appears feasible for histological evaluation in ABCB4 deficiency.

Review article: liver disease in adults with variants in the cholestasis-related genes ABCB11, ABCB4 and ATP8B1.

Children with intrahepatic cholestasis and genetic variants which result in the disruption of the formation and maintenance of bile (ABCB11, ABCB4 and ATP8B1) generally have a rapidly progressive clinical course. Adults with different phenotypes of cholestasis are increasingly being evaluated for variants in these genes associated with childhood diseases. To review the literature with respect to the presence of variants in cholestasis-related genes in adults with various liver phenotypes, and provide clinical implications of the findings. A search of the literature on variants in specific cholestasis-related genes in adults was conducted. The common variant p.Val444Ala in ABCB11 confers increased risk of drug-induced liver injury and intrahepatic cholestasis of pregnancy (ICP). Individuals with variants in ABCB4 are at risk of ICP and low phospholipid-associated cholelithiasis. Variants in ABCB4, and possibly ABCB11 and ATP8B1, can be identified in up to a third of patients with cryptogenic chronic cholestasis. Individuals with variants in ABCB11 rarely develop cholestasis until BSEP function dips below a threshold, which is also affected by other factors (e.g., drugs, hormones). However, variants in ABCB4 and consequent reduction in MDR3 protein, have a more linear dose-response curve. In individuals with an ABCB11 variant, medications known to reduce BSEP activity should be used cautiously; they should be monitored during pregnancy for ICP; and first-degree relatives should be counselled and screened. No proven management strategy exists, although ursodeoxycholic acid may be beneficial. Further work is needed to define the genotype-phenotype correlation and natural history, and to evaluate the penetrance.

Should patients with symptomatic cholelithiasis before 30 years of age be tested for ABCB4 gene mutations?

Background and aims Low phospholipid-associated cholelithiasis syndrome (LPAC) is characterized by recurrent symptomatic cholelithiasis in young adults associated with ABCB4 gene mutations. Current diagnosing criteria are complex and heterogeneous, making this a largely underdiagnosed entity. Also, although recommended, genetic testing is not necessary for the diagnosis and its real advantages are not clear. The aim of our study was to explore the prevalence of ABCB4 mutations in symptomatic patients with cholelithiasis before the age of 30. Methods We conducted a multicentric prospective cohort study including patients with symptomatic cholelithiasis presenting before 30 years of age in 4 Portuguese centres between January 2017 and December 2019. ABCB4 gene was analyzed by next generation sequencing (NGS) including all exons and flanking regions. In 17/32 patients ABCB11 and ATP8B1 variants were also analyzed by NGS. Results Thirty-two patients were included (75% females, median age of symptom onset was 23 ± 5 years). We found that 8/32 (25%) patients had mutations in ABCB4 gene, 3/17 (18%) in ATP8B1 gene and 1/17 (6%) in ABCB11 gene. 44% (8/18) of patients with LPAC syndrome criteria had identified variants, while the prevalence of mutations in patients with symptoms onset before 30 as sole criteria was 29%. Conclusion Our results suggest that LPAC should be systematically suspected and investigated in patients with symptomatic cholelithiasis before age of thirty, but genetic testing should only be attempted in patients complying with the more stringent LPAC criteria.

Low phospholipid-associated cholelithiasis syndrome: A rare cause of acute pancreatitis that should not be neglected.

BACKGROUNDLow phospholipid-associated cholelithiasis (LPAC) syndrome is a very particular form of biliary lithiasis with no excess of cholesterol secretion into bile, but a decrease in phosphatidylcholine secretion, which is responsible for stones forming not only in the gallbladder, but also in the liver. LPAC syndrome may be underreported due to a lack of testing resulting from insufficient awareness among clinicians.AIMTo describe the clinical and radiological characteristics of patients with LPAC syndrome to better identify and diagnose the disease.METHODSWe prospectively evaluated all patients aged over 18 years old who were consulted or hospitalized in two hospitals in Paris, France (Bichat University Hospital and Croix-Saint-Simon Hospital) between January 1, 2017 and August 31, 2018. All patients whose profiles led to a clinical suspicion of LPAC syndrome underwent a liver ultrasound examination performed by an experienced radiologist to confirm the diagnosis of LPAC syndrome. Twenty-four patients were selected. Data about the patients’ general characteristics, their medical history, their symptoms, and their blood tests results were collected during both their initial hospitalization and follow-up. Cytolysis and cholestasis were expressed compared to the normal values (N) of serum aspartate and alanine transaminase activities, and to the normal value of alkaline phosphatase level, respectively. The subjects were systematically reevaluated and asked about their symptoms 6 mo after inclusion in the study through an in-person medical appointment or phone call. Genetic testing was not performed systematically, but according to the decision of each physician.RESULTSMost patients were young (median age of 37 years), male (58%), and not overweight (median body mass index was 24). Many had a personal history of acute pancreatitis (54%) or cholecystectomy (42%), and a family history of gallstones in first-degree relatives (30%). LPAC syndrome was identified primarily in patients with recurring biliary pain (88%) or after a new episode of acute pancreatitis (38%). When present, cytolysis and cholestasis were not severe (2.8N and 1.7N, respectively) and disappeared quickly. Interestingly, four patients from the same family were diagnosed with LPAC syndrome. At ultrasound examination, the most frequent findings in intrahepatic bile ducts were comet-tail artifacts (96%), microlithiasis (83%), and acoustic shadows (71%). Computed tomography scans and magnetic resonance imaging were performed on 15 and three patients, respectively, but microlithiasis was not detected. Complications of LPAC syndrome required hospitalizing 18 patients (75%) in a conventional care unit for a mean duration of 6.8 d. None of them died. Treatment with ursodeoxycholic acid (UDCA) was effective and well-tolerated in almost all patients (94%) with a rapid onset of action (3.4 wk). Twelve patients’ (67%) adherence to UDCA treatment was considered “good.” Five patients (36%) underwent cholecystectomy (three of them were treated both by UDCA and cholecystectomy). Despite UDCA efficacy, biliary pain recurred in five patients (28%), three of whom adhered well to treatment guidelines.CONCLUSIONLPAC syndrome is easy to diagnose and treat; therefore, it should no longer be overlooked. To increase its detection rate, all patients who experience recurrent biliary symptoms following an episode of acute pancreatitis should undergo an ultrasound examination performed by a radiologist with knowledge of the disease.

Genetic contribution of ABCC2 to Dubin-Johnson syndrome and inherited cholestatic disorders.

The ABCC2 gene is implicated in Dubin-Johnson syndrome (DJS), a rare autosomal recessive liver disorder. The primary aim of this study was to determine the diagnostic value of ABCC2 genetic testing in the largest cohort of DJS reported to date. The high number of patients with cholestatic manifestations in this series prompted us to evaluate the genetic contribution of rare, potentially pathogenic ABCC2 variants to other inherited cholestatic disorders. The cohort study included 32 patients with clinical DJS diagnosis, and 372 patients referred for the following disorders: low phospholipid-associated cholelithiasis (LPAC) syndrome, intrahepatic cholestasis of pregnancy (ICP) and benign recurrent intrahepatic cholestasis (BRIC). ABCC2 was screened by next-generation sequencing. Most patients with clinical DJS had positive genetic diagnosis (n=30; 94%), with a great diversity of point mutations and copy number variations in ABCC2. Strikingly, eight (27%) of these patients showed transient cholestatic features at presentation: four neonatal cholestasis, two ICP, one contraceptive-induced cholestasis and one sporadic cholestasis. Conversely, the frequency of rare, heterozygous, potentially pathogenic ABCC2 variants in patients with LPAC, ICP or BRIC did not differ significantly from that of the general population. This large series reveals that DJS is a highly homogeneous Mendelian disorder involving a large spectrum of ABCC2 variants. Genetic testing is crucial to establish early DJS diagnosis in patients with atypical presentations, such as neonatal cholestasis. This study also provides no evidence for the contribution of rare, potentially pathogenic ABCC2 variants to other inherited cholestatic disorders.

A homozygous ABCB4 mutation causing an LPAC syndrome evolves into cholangiocarcinoma

Low phospholipid-associated cholelithiasis (LPAC) is characterized by the association of ABCB4 mutations and low biliary phospholipid concentration with symptomatic and recurring cholelithiasis. In the present study, we reported a case of a 63-year-old woman, who presented a biliary pain beginning at the age of 30, recurrent after cholecystectomy, along with “comet-tail shadows” revealed by ultrasonography thus, fulfilling the diagnosis of LPAC. This disease evolved into a cholangiocarcinoma. To understand the molecular basis of this phenotype, we performed the ABCB4 gene sequencing, followed by in silico analysis and Q-RT-PCR assay. The results displayed a homozygous missense sequence variation (c.140G > A, p.Arg47Gln), predicted as pathogenic according to MutPred. Accordingly, this gave rise to a decreased hepatic ABCB4 mRNA level and structural alterations of the mutated protein. Eventually, we reported, here, the first description of an ABCB4 missense mutation (p.Arg47Gln) at homozygous state in a Tunisian LPAC syndrome. An elucidation of its functional consequences was performed. Besides, this case suggests that the delayed diagnosis of LPAC syndrome and the lack of UDCA treatment may contribute in the development of complications, such as cholangiocarcinoma.

Lack of phospholipids in bile enhances cholesterol cholelithogenesis in the ATP‐binding cassette transporter B4 (Abcb4) knockout mice

BackgroundBiliary phospholipids play a key role in transporting cholesterol (Ch) by forming unilamellar and multilamellar vesicles that display a significantly higher ability to solubilize Ch in bile compared to simple and mixed micelles. The ATP‐binding cassette transporter B4 (ABCB4) is responsible for hepatic phospholipid secretion and its deletion in the liver causes a lack of phospholipids in bile of mice. Our aim is to explore whether targeted deletion of the Abcb4 gene in the liver leads to more rapid Ch crystallization and gallstone formation in Abcb4 knockout (KO) mice fed even a low Ch diet compared to wild‐type (WT) mice.MethodsThe critical role of biliary phospholipids in Ch crystallization and gallstone formation was investigated by physical‐chemical methods in male Abcb4 KO vs WT mice fed a chow diet (on day 0) and a special diet containing 0.1% Ch, 15% butterfat and 0.25% cholic acid for 4 wk.ResultsOn the chow diet (day 0), biliary phospholipids are 18.1±0.3 mM in pooled gallbladder bile of WT mice. However, no phospholipids are detected in Abcb4 KO mice fed either the chow or the special diet. After 1 wk of feeding the special diet, phase diagram analysis finds that lipid composition of pooled gallbladder bile of Abcb4 KO mice is located in crystallization region A. Moreover, many needle‐like Ch crystals, typical Ch monohydrate crystals, sandy stones and small gallstones (0.1–0.2 mm in diameter), but not liquid crystals, are detected in bile by phase contrast and polarizing light microscopy. This shows that lack of phospholipids in bile produces anhydrous crystalline metastable intermediates that rapidly evolve to Ch monohydrate crystals from supersaturated bile. In contrast, lipid composition of pooled gallbladder bile of WT mice is still within the micellar zone, indicating that bile is unsaturated with Ch. After 4 wk of feeding the special diet, lipid composition of pooled gallbladder bile of Abcb4 KO mice still stays in crystallization region A, with many larger gallstones (0.3–0.6 mm in diameter) being formed in the gallbladder. Notably, lipid composition of pooled gallbladder bile of WT mice enters crystallization region C, as analyzed by phase diagram. Thus, many liquid crystals (i.e., unilamellar and multilamellar vesicles) and classical solid plate‐like Ch monohydrate crystals, but not gallstones, are found in the gallbladder of WT mice. These results indicate that solid Ch crystals are formed through the liquid crystalline pathway in WT mice.ConclusionsLack of biliary phospholipids caused by the Abcb4 deletion in the mouse liver is a critical risk factor for Ch gallstone disease by significantly reducing Ch solubility in bile through disrupting the liquid crystalline pathway, whereas it leads to more rapid Ch crystallization via the anhydrous crystalline pathway. Our findings provide novel insight into the pathophysiological mechanisms of why Ch gallstones are rapidly formed in patients with the ABCB4 mutations, thereby leading to low phospholipid‐associated cholelithiasis, a rare biliary disease caused by a single‐gene mutation.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Low-Phospholipid Associated Cholelithiasis (LPAC) syndrome: A synthetic review.

Low-Phospholipid Associated Cholelithiasis (LPAC) is a genetic disease responsible for the development of intrahepatic lithiasis. It is associated with a mutation of the ABCB4 gene which codes for protein MDR3, a biliary carrier. As a nosological entity, it is defined by presence of two of the three following criteria: age less than 40 years at onset of biliary symptoms, recurrence of biliary symptoms after cholecystectomy, and intrahepatic hyperechogenic foci detected by ultrasound. While the majority of clinical forms are simple, there also exist complicated forms, involving extended intrahepatic lithiasis and its consequences: lithiasis migration, acute cholangitis, intrahepatic abscess. Chronic evolution can lead to secondary sclerosing cholangitis or secondary biliary cirrhosis. In unusual cases, degeneration into cholangiocarcinoma may occur. Treatment is built around ursodeoxycholic acid, which yields dissolution of biliary calculi. Complicated forms may call for interventional, radiological, endoscopic or surgical treatment. This synthetic review illustrates and summarizes the different aspects of this entity, from simple gallbladder lithiasis to cholangiocarcinoma, as well as secondary biliary cirrhosis requiring liver transplant, on the basis of clinical cases and the iconography of patients treated in our ward.