Genetics of biliary tract diseases: new insights into gallstone disease and biliary tract cancers

Upregulated plasma and urinary levels of nucleosides as biological markers in the diagnosis of primary gallbladder cancer

We first detected aberrant nucleoside levels in the plasma, urine, bile, and tissues from cases and controls to explore them as biomarkers in the diagnosis of gallbladder cancer. Reversed-phase high-performance liquid chromatography was used to assess the levels of ten nucleosides in these samples from gallbladder cancer patients, gallstone patients, and healthy controls. Plasma and urine samples were collected from patients with gallbladder cancer (n = 202), patients with gallstones (n = 203), and healthy controls (n = 205); bile and tissue samples were collected from 91 gallbladder cancer patients, 93 gallstone patients; and 90 were donated after cardiac death. Of the ten nucleosides analyzed, eight urinary nucleosides, five plasma nucleosides, three bile nucleosides, and one tissue nucleoside were significantly upregulated in the gallbladder cancer patients compared to control groups (p < 0.05). Among these upregulated nucleosides, the sensitivity, specificity, and accuracy of urinary nucleosides in the diagnosis of gallbladder cancer patients were 89.4, 97.1, and 95.7%, respectively, those of plasma nucleosides were 91.2, 95.6, and 94.2%, respectively, those of bile nucleosides were 95.3, 96.4, and 95.1%, respectively, and those of tissue nucleosides were 86.2, 93.8, and 92.6%, respectively. These results suggest that nucleosides may be as useful as biological markers for gallbladder cancer.

A common variant in the precursor miR-146a sequence does not predispose to cholangiocarcinoma in a large European cohort

BACKGROUND

Micro-RNAs (miRNAs) are small, non-coding RNA species considered to fine-tune basic cellular functions by modulating target gene translation and/or mRNA stability. A common G/C polymorphism (rs2910164) in the precursor (pre-) miR-146a gene engaged in NF-κB signaling and apoptosis pathways has been reported to modulate the genetic risk of hepatocellular carcinoma by increased G-allelic production of mature miR-146a. We investigated rs2910164 in a large European-based cholangiocarcinoma (CCA) cohort.

METHODS

We recruited 182 CCA patients and 350 controls in three academic medical centers. Genotyping for rs2910164 was performed by PCR-based assays with 5'-nuclease and fluorescence detection. Genotype frequencies were tested for consistency with the Hardy-Weinberg equilibrium using an exact test; allelic and genotypic differences between the patients and controls were assessed by the Chi-square test and Armitage's trend test. Exploratory subgroup analyses included gender, tumor localization (extra- versus intrahepatic CCA) and early-onset CCA.

RESULTS

Genotype distributions were consistent with the Hardy-Weinberg equilibrium. No significant differences in either allele or genotype distributions were detected between the CCA and control groups or the respective subgroups investigated. However, there was a trend for a protective effect of the heterozygous single-nucleotide polymorphism state GC, as indicated by an underrepresentation in the CCA group in general (29% vs 35%; P=0.18) and, in particular, for extrahepatic tumor sites (26% vs 35%; OR=0.67; 95% CI, 0.43-1.02; P=0.065).

CONCLUSIONS

Our data do not support a prominent contribution of the pre-miR-146a sequence variant in the genetic predisposition to CCA. However, current studies functionally characterizing rs2910164 have proposed that distinct repertoires of target genes are addressed by genotype-specific mature miR-146a species. Given the detected trend towards a potentially protective role of GC heterozygosity, a subtle modulation of genetic CCA risk by the pre-miR-146a GC genotype may exist and should be evaluated further.

Potential genotype-specific single nucleotide polymorphism interaction of common variation in p53 and its negative regulator mdm2 in cholangiocarcinoma susceptibility

Aberrant cell cycle control and apoptosis deregulation are involved in biliary carcinogenesis. The tumor suppressor gene p53 and its key negative regulator murine double minute 2 (mdm2) cooperate in modulating these basic cell functions and germline p53 alteration promotes cholangiocarcinoma (CCA) formation in animal models. The potential association between common functional genetic variation in p53 (SNP72 G/C) and mdm2 (SNP309 T/G) and susceptibility to bile duct cancer, however, has not been studied. p53/SNP72 G/C (rs1042522) and mdm2/SNP309 T/G (rs2279744) were genotyped in 182 Caucasian CCA patients and 350 controls using TaqMan assays. Allelic and genotypic differences, including exploratory data analyses (according to gender, tumor localization, early onset and genotypic interactions) were compared in contingency tables using the χ(2) and Fisher's exact tests. The overall comparison of allele and genotype frequencies yielded no significant association between either SNP and CCA susceptibility. Similarly, gender- and localization-specific analyses did not reveal deviations in allelic or genotypic distributions. In carriers of the low-apoptotic p53 genotype CC, the mdm2 SNP309 T allele conferred borderline significant CCA risk [P=0.049; odds ratio (OR), 4.36; 95% CI, 0.92-20.77]. Power analysis confirmed adequate statistical power to exclude major SNP effects (each >97% for OR 1.7). Collectively, the results we obtained from the largest European CCA cohort do not support the hypothesis of a prominent role of common p53 and mdm2 variation in the genetic susceptibility to bile duct cancer. However, epistatic effects may modulate genetic CCA risk in individual subsets.

Effects of SLC10A2 variant rs9514089 on gallstone risk and serum cholesterol levels- meta-analysis of three independent cohorts

Background

Recently, a single nucleotide polymorphism (SNP) rs9514089 in SLC10A2 (apical sodium-dependent bile acid transporter gene) has been identified as a susceptibility variant for cholelithiasis in humans.

Methods

Here we assessed the effects of rs9514089 on gallstone risk and related phenotypes of the metabolic syndrome in the self-contained population of Sorbs (183 cases with gallstones/826 controls). Furthermore, we performed a meta-analysis for effects of rs9514089 on susceptibility for cholelithiasis in three independent cohorts (Stuttgart: 56 cases/71 controls, Aachen: 184 cases/184 controls and Sorbs).

Results

There was no significant association of rs9514089 with gallstone risk, serum lipid parameters and BMI in the Sorbs and in the meta-analysis of all three cohorts (p > 0.05). There was an effect trend in the subgroup of lean subjects but based on different effect directions in the three cohorts there was no significant association in the meta-analysis.

Conclusions

We were not able to replicate the effect of rs9514089 on gallstone risk in the Sorbs. Further analyses in larger cohorts are required to finally assess the role of genetic variants in SLC10A2 in human gallstone development and lipid metabolism.

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

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

Heterozygosity for the alpha1-antitrypsin Z allele may confer genetic risk of cholangiocarcinoma

BACKGROUND

Alpha1-antitrypsin (α1AT) deficiency caused by Z allele homozygosity represents a well-established risk factor for hepatocellular carcinoma. Previous studies have also implicated α1AT Z heterozygosity in cholangiocarcinogenesis.

AIM

To assess the 'common' Z and S alleles as well as the promoter variant rs8004738 for association with cholangiocarcinoma.

METHODS

We genotyped 182 Caucasian patients and 350 controls for rs28929474 (Z), rs17580 (S) and the variant rs8004738. Exploratory analyses were performed in relation to gender and cholangiocarcinoma localisation.

RESULTS

rs28929474 was significantly enriched in the cholangiocarcinoma group (4.1 vs. 1.7%; OR 2.46, 95% CI 1.14-5.32; Bonferroni corrected p(c) = 0.036), reinforced by Armitage trend testing (OR 2.53; p(c) = 0.032). The rs8004738 (promoter) minor allele tended to be overrepresented in Z heterozygotes (30.0 vs. 16.7%: P = 0.13). Exploratory data analyses suggested a high genetic risk for extrahepatic tumour localisation (OR 3.0; p(c) = 0.016) and potentially female Z allele carriers (OR 3.37; unadjusted P = 0.022, p(c) = 0.088).

CONCLUSIONS

These data point to a novel role of α1AT Z heterozygosity as a potential genetic susceptibility factor for cholangiocarcinoma formation and suggest a contribution of aberrant α1AT function in biliary carcinogenesis. However, given the overall low rs28929474 minor allele frequency, larger studies are warranted to confirm and extend our findings.

Sterol transporter adenosine triphosphate-binding cassette transporter G8, gallstones, and biliary cancer in 62,000 individuals from the general population

Gallstone disease, a risk factor for biliary cancer, has a strong heritable component, but the underlying genes are largely unknown. To test the hypothesis that ABCG8 (adenosine triphosphate-binding cassette transporter G8) Asp19His (D19H) genotype predicted risk of gallstones and biliary cancer in the general population, we studied 62,279 white individuals from The Copenhagen City Heart Study and The Copenhagen General Population Study, randomly selected to reflect the adult Danish population aged 20 to 80+ years. Endpoints were recorded from January 1976 through May 2009. During a mean follow-up of, respectively, 31 and 4.4 years, 3124 participants developed symptomatic gallstone disease and 30 developed biliary cancer. The multifactorially adjusted hazard ratio for symptomatic gallstone disease was 1.9 (95% confidence interval, 1.7-2.1) in DH heterozygotes (prevalence, 12%), and 3.3 (2.3-4.6) in HH homozygotes (0.4%) versus noncarriers (P for trend <0.001). Mean age at onset of symptomatic gallstone disease was 56 years for noncarriers, 54 for DH heterozygotes, and 52 for HH homozygotes (P for trend <0.001). The fraction of all gallstones attributed to D19H was 11%. The multifactorially adjusted hazard ratio for biliary cancer was 4.0 (1.9-8.4) in DH heterozygotes and HH homozygotes combined versus noncarriers (P < 0.001). The fraction of all biliary cancers attributed to the D19H genotype was 27%. Finally, D19H genotype associated with stepwise increases in plasma levels of alanine aminotransferase and gamma glutamyltransferase of up to 14% and 25% in HH homozygotes, and with corresponding stepwise reductions in plasma levels of total and low-density lipoprotein cholesterol of up to 5% versus noncarriers (all comparisons, P for trend <0.001).

CONCLUSION

In this general population cohort, ABCG8 D19H genotype was an important predictor of both symptomatic gallstone disease and biliary cancer.

Descriptive epidemiology of cholangiocarcinoma in Italy

BACKGROUND

Very little data exist on the epidemiology of cholangiocarcinoma in Italy.

AIM

We focus on the descriptive epidemiology of cholangiocarcinoma in Italy.

METHODS

Data on incidence were obtained from the Italian Association of Tumour Registries while mortality data were obtained from the Italian National Institute of Statistics.

RESULTS

A progressive increase of incidence with age was seen for extra-hepatic, intra-hepatic and not otherwise specified cholangiocarcinoma. Crude incidence rates were higher for extra-hepatic cholangiocarcinoma than those for intra-hepatic cholangiocarcinoma and in men compared to women. An increasing incidence trend was observed, from 1988 to 2005, for both extra-hepatic- and intra-hepatic cholangiocarcinoma with a 3-6% yearly increase and with a rate of increase higher for men than for women and for intra-hepatic- than for extra-hepatic cholangiocarcinoma. For intra-hepatic cholangiocarcinoma, the mortality rates progressively increased from 0.15 per million in 1980 to 5.9 per million in 2003, when mortality for this cancer surpassed extra-hepatic cholangiocarcinoma. Mortality rates for extra-hepatic cholangiocarcinoma showed an increasing trend from 1980 to 1994 but, in contrast to intra-hepatic cholangiocarcinoma, a stable or slightly decreasing trend from 1995 to 2003 was observed.

CONCLUSIONS

In Italy, cholangiocarcinoma showed a progressive increase in incidence and mortality in the last two decades mainly in intra-hepatic cholangiocarcinoma.

High incidence of cholesterol gallstone disease in type 1 Gaucher disease: characterizing the biliary phenotype of type 1 Gaucher disease

BACKGROUND

In Gaucher disease (GD), lysosomal glucocerebrosidase deficiency results in glucosylceramide accumulation in macrophage lysosomes. Hepatocytes do not accumulate glucosylceramide due in part to biliary secretion. Although gallstones (GS) occur in type 1 Gaucher disease (GD1), the chemical nature of stones, their association with metabolic parameters, and whether bile composition is altered are not understood. We assessed the prevalence of GS, their chemical composition, biliary lipids, and associated metabolic factors.

METHODS

The study cohort comprised 417 patients comprehensively evaluated for GD1 severity. Ascertainment of GS, fasting lipoprotein profile, and bile lipid analyses were performed.

RESULTS

The prevalence of GS in GD1 was 32%. Compared with men, the prevalence of GS was higher in women, increasing from 4.2% and 11.8% at age 20-29 years to 71% and 60% at age >70 years, respectively. Patients with GS were more likely to be asplenic (p < 0.0001), older (p < 0.0001), have higher low-density lipoprotein (LDL) cholesterol (p = 0.002), and more severe GD1 disease compared with those without GS. On multiple logistic regression analysis, factors associated with GS were age (p < 0.001), female sex (p = 0.03), and splenectomy (p = 0.005). Compared with the general population, prevalence of GS was approximately 5-fold higher. Bile lipid analyses revealed cholesterol stones in five patients and pigment stones in one. Bile lipid composition was abnormal and contained glucosylceramide.

CONCLUSIONS

Our results point to a metabolic syndrome in GD1 consisting of a propensity to cholesterol GS, low high-density lipoprotein (HDL) cholesterol, LDL cholesterol, and body mass index (BMI) associated with abnormal biliary lipid secretion.

Genetics of cholestatic liver disease in 2010

PURPOSE OF REVIEW

Many of the cholestatic diseases show similar clinical features, despite underlying differences in the genetic etiology. The present review aims to present recent insight into this etiological heterogeneity.

RECENT FINDINGS

Mutations in the genes causing progressive familial intrahepatic cholestasis are also involved in less severe phenotypes like benign recurrent intrahepatic cholestasis, gallstone disease, intrahepatic cholestasis of pregnancy and drug-induced cholestasis. This probably represents a continuum of severity of the mutations involved, but also complex patterns of inheritance ranging from monogenic autosomal recessive disorders to heterozygosity only conferring a moderate increase in disease risk, where additional genetic or environmental factors are needed to acquire a disease phenotype. Recent genome-wide association studies in the inflammatory cholestatic diseases primary biliary cirrhosis and primary sclerosing cholangitis have revealed susceptibility genes involved in autoimmunity and inflammatory bowel disease, whereas the genetic risk factors for the biliary preference of these diseases remain unknown.

SUMMARY

The complexity of the genetic contribution to cholestatic liver disease needs to be accounted for to fully understand the pathogenesis of these conditions.