Biliary transporter gene mutations in severe intrahepatic cholestasis of pregnancy: Diagnostic and management implications

Rare variant contribution to cholestatic liver disease in a South Asian population in the United Kingdom

This study assessed the contribution of five genes previously known to be involved in cholestatic liver disease in British Bangladeshi and Pakistani people. Five genes (ABCB4, ABCB11, ATP8B1, NR1H4, TJP2) were interrogated by exome sequencing data of 5236 volunteers. Included were non-synonymous or loss of function (LoF) variants with a minor allele frequency < 5%. Variants were filtered, and annotated to perform rare variant burden analysis, protein structure, and modelling analysis in-silico. Out of 314 non-synonymous variants, 180 fulfilled the inclusion criteria and were mostly heterozygous unless specified. 90 were novel and of those variants, 22 were considered likely pathogenic and 9 pathogenic. We identified variants in volunteers with gallstone disease (n = 31), intrahepatic cholestasis of pregnancy (ICP, n = 16), cholangiocarcinoma and cirrhosis (n = 2). Fourteen novel LoF variants were identified: 7 frameshift, 5 introduction of premature stop codon and 2 splice acceptor variants. The rare variant burden was significantly increased in ABCB11. Protein modelling demonstrated variants that appeared to likely cause significant structural alterations. This study highlights the significant genetic burden contributing to cholestatic liver disease. Novel likely pathogenic and pathogenic variants were identified addressing the underrepresentation of diverse ancestry groups in genomic research.

Contraceptive vaginal ring-induced cholestasis in a patient with a history of intrahepatic cholestasis of pregnancy

INTRODUCTION

Intrahepatic cholestasis of pregnancy (ICP) is a heterogeneous group of liver disorders with a high recurrence rate. Patients with a history of ICP are at risk of developing contraceptive-induced cholestasis, especially if they harbour a biliary transporter mutation. We report the first case of drug-induced cholestasis associated with a contraceptive vaginal ring (CVR) in a patient with a prior history of ICP.

PRESENTATION

Our patient was a women with a history of multiple pregnancies and spontaneous abortions and early and severe ICP. Two to four weeks after initiation of CVR, she developed signs and symptoms of cholestasis, which resolved after discontinuation of the CVR. A thorough investigation to exclude other plausible causes of cholestasis was performed, including a liver biopsy. Genetic testing revealed pathogenic mutations in both the ABCB11 and ABCB4 genes.

DISCUSSION

Although a history of ICP used to be an absolute contraindication for oral contraceptive pills (OCP), recent studies suggest a lower risk of cholestasis associated with low-dose oestrogen pills (20-35 mcg compared to the original 50 mcg). No previous case report could confirm the theoretical risk associated with the use of a CVR, which delivers a very low estrogen dose (15 mcg). The two biliary transporter mutations identified in our case could potentially explain the patient's susceptibility to the cholestatic effect of oestrogen.

CONCLUSION

This case illustrates that CVR can trigger drug-induced cholestasis in a susceptible patient. While such cases should not discourage the trial of low-dose hormonal contraception in women with prior ICP, an appropriate follow-up is necessary to ensure early detection and treatment of drug-induced cholestasis.

Intrahepatic Cholestasis of Pregnancy: Natural History and Current Management

Intrahepatic cholestasis of pregnancy (ICP) is a common disorder in the second half of pregnancy characterized by pruritus and elevated serum bile acids (BAs) with spontaneous resolution after delivery. ICP carries a risk of adverse effects on the fetus which correlates with the degree of BA elevation. ICP occurs in genetically susceptible women as the reproductive hormones increase during pregnancy. Ursodeoxycholic acid is still considered the first-line treatment for ICP though it is of unproven benefit in preventing adverse effects on the fetus. Fetal complications, such as stillbirth, increase with gestational age, so preterm delivery is generally performed in cases of severe ICP, defined as BA levels above 40 μmol/L. ICP may recur in future pregnancies and is associated with an increased risk for future hepatobiliary, immune mediated, and cardiovascular diseases. Children born of mothers with ICP have normal development but may have a risk for subsequent metabolic disease.

ROC Curve Analysis of the Sensitivity and Specificity of Biochemical Detection of Intrahepatic Cholestasis during Pregnancy

INTRODUCTION

Intrahepatic cholestasis of pregnancy (ICP) is associated with an increased risk of adverse pregnancy outcomes in mothers and infants. The aim was to evaluate the sensitivity and specificity of biochemical detection of ICP by ROC curve and to determine the threshold of more reliable experimental indicators.

MATERIALS AND METHODS

305 patients and 305 healthy pregnant women were enrolled in the study.

RESULTS

The average levels of TBA, ALT, and AST in the ICP group were much higher than those in the control group (P<0. 001); the area of both CG and TBA under ROC curve was up to 0.99, the sensitivity was 97.7%, and the specificity was 99.3%.

CONCLUSIONS

This study did not find any single specificity and sensitivity markers that could be used to reliably diagnose ICP. In the future, we will pay more attention to the correlation between sensitive biochemical indicators and adverse pregnancy outcomes.

Cholestasis in the Premature Infant

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

Bile Acids as Metabolic Regulators and Nutrient Sensors

Bile acids facilitate nutrient absorption and are endogenous ligands for nuclear receptors that regulate lipid and energy metabolism. The brain-gut-liver axis plays an essential role in maintaining overall glucose, bile acid, and immune homeostasis. Fasting and feeding transitions alter nutrient content in the gut, which influences bile acid composition and pool size. In turn, bile acid signaling controls lipid and glucose use and protection against inflammation. Altered bile acid metabolism resulting from gene mutations, high-fat diets, alcohol, or circadian disruption can contribute to cholestatic and inflammatory diseases, diabetes, and obesity. Bile acids and their derivatives are valuable therapeutic agents for treating these inflammatory metabolic diseases.