Apolipoprotein B-100 gene Xba I polymorphism and cholesterol gallstone disease

Association of apolipoprotein B XbaI (rs693) polymorphism and gallstone disease risk based on a comprehensive analysis

BACKGROUND

Our aim was to investigate the association between XbaI gene polymorphisms in the apolipoprotein B (APOB) gene and gallstone disease (GD) risk through a comparison of the allele and genotype distribution frequencies at this site using meta-analysis.

METHODS

A literature search was performed using PubMed and Wanfang through Jun 1, 2020. Odds ratios (ORs) and 95 % confidence intervals (CIs) were used to assess the strength of associations.

RESULTS

After a comprehensive search, 14 different articles that met the inclusion criteria were selected, with 1583 cases and 1794 controls. Individuals carrying the A-allele or AA genotype of the rs693 polymorphism were determined to possibly have an increased risk of GD. For example, there was a significant relationship between the rs693 polymorphism and increased GD risk in the whole group (OR: 1.40, 95 % CI: 1.05-1.87 in the allelic contrast model), the Asian population (OR: 1.58, 95 % CI: 1.48-2.84 in the heterozygote model), and the hospital-based source of the control (OR: 1.79, 95 % CI: 1.13-2.84 in the dominant model).

CONCLUSIONS

This study suggests that the APOB rs693 polymorphism is potentially associated with GD susceptibility, which might offer a detection marker for use in future large scale clinic research.

Associations of the APOB rs693 and rs17240441 polymorphisms with plasma APOB and lipid levels: a meta-analysis

BACKGROUND

The associations of the apolipoprotein B gene (APOB) rs693 and rs17240441 polymorphisms with plasma levels of APOB and lipids have been widely explored, but the results were inconclusive. This meta-analysis aimed to clarify the associations of the rs693 and rs17240441 polymorphisms with fasting APOB and lipid levels.

METHODS

Sixty-one studies (50,018 subjects) and 23 studies (8425 subjects) were respectively identified for the rs693 and rs17240441 polymorphisms by searching in PubMed, Google Scholar, Web of Science, Cochrane Library, Wanfang, VIP and CNKI databases. The following information was collected for each study: first author, age, gender, ethnicity, health condition, sample size, genotyping, lipid assay method, mean and standard deviation or standard error of APOB and lipid variables by genotypes. A dominant model was used for this meta-analysis.

RESULTS

The carriers of the rs693 variant allele (T) had higher levels of APOB [standardized mean difference (SMD) = 0.26, 95% confidence interval (CI) = 0.16-0.36, P < 0.01], triglycerides (TG) (SMD = 0.12, 95% CI = 0.05-0.20, P < 0.01), total cholesterol (TC) (SMD = 0.24, 95% CI = 0.17-0.30, P < 0.01) and low-density lipoprotein cholesterol (LDL-C) (SMD = 0.22, 95% CI = 0.14-0.30, P < 0.01), and lower levels of high-density lipoprotein cholesterol (HDL-C) (SMD = -0.06, 95% CI = -0.11-0.01, P = 0.01) than the non-carriers. The carriers of the rs17240441 deletion allele had higher levels of APOB (SMD = 0.13, 95% CI = 0.06-0.20, P < 0.01), TC (SMD = 0.17, 95% CI = 0.07-0.26, P < 0.01) and LDL-C (SMD = 0.15, 95% CI = 0.07-0.23, P < 0.01) than the non-carriers.

CONCLUSIONS

The rs693 polymorphism is significantly associated with higher levels of APOB, TG, TC and LDL-C, and lower levels of HDL-C. The rs17240441 polymorphism is significantly associated with higher levels of APOB, TC and LDL-C. Further studies are needed to elucidate the underlying mechanisms.

Risk Factors for Cholelithiasis

Gallstone disease is one of the most common public health problems in the United States. Approximately 10%-20% of the national adult populations currently carry gallstones, and gallstone prevalence is rising. In addition, nearly 750,000 cholecystectomies are performed annually in the United States; direct and indirect costs of gallbladder surgery are estimated to be $6.5 billion. Cholelithiasis is also strongly associated with gallbladder, pancreatic, and colorectal cancer occurrence. Moreover, the National Institutes of Health estimates that almost 3,000 deaths (0.12% of all deaths) per year are attributed to complications of cholelithiasis and gallbladder disease. Although extensive research has tried to identify risk factors for cholelithiasis, several studies indicate that definitive findings still remain elusive. In this review, predisposing factors for cholelithiasis are identified, the pathophysiology of gallstone disease is described, and nonsurgical preventive options are discussed. Understanding the risk factors for cholelithiasis may not only be useful in assisting nurses to provide resources and education for patients who are diagnosed with gallstones, but also in developing novel preventive measures for the disease.

Hepatitis C Virus Infection Is Positively Associated with Gallstones in Liver Cirrhosis

AIM

To elucidate the prevalence and risk factors of gallstone disease (GD) among patients with liver disease and explore their association with the aetiology and severity of hepatic injury.

METHODS

We analysed 4,832 subjects of hepatic injury induced by one of the following aetiologies: hepatitis B virus (HBV) infection, hepatitis C virus (HCV) infection, excessive alcohol consumption. The risk factors significantly associated with GD were analysed using stepwise logistic regression analysis, the influence of aetiology and severity of liver disease on the prevalence of GD were assessed by multiple logistic regression analysis adjusting for confounding factors.

RESULTS

Three thousand forty eight patients were of positive HBV surface antigen alone with a prevalence of GD of 18.6%, 526 were tested as positive Anti-HCV alone with a prevalence of GD of 22.4%, and 1,258 were identified with excessive alcohol consumption patterns with a prevalence of GD of 13.5%. In each aetiological category, the prevalence of GD increased by age. Stepwise logistic regression analysis showed that age, female, low-density lipoprotein-cholesterol (LDL-Cho), family history of GD, HBV infection, HCV infection, chronic hepatitis and cirrhosis were independent factors associated with GD. After adjusting for age, LDL-Cho and family history of GD, the prevalence of gallstone disease was significantly associated with HCV-related cirrhosis in both genders, HBV-related cirrhosis in males and alcohol-related cirrhosis in females compared with patients with less severe liver disease [corrected]. After adjusting for gender, age, LDL-Cho and family history of GD, patients with HCV-related cirrhosis (OR 2.66, 95% CI 1.49-3.84) but not HBV-related cirrhosis (OR 1.52, 95% CI 0.73-1.82) were more likely to have GD compared with alcohol-related cirrhosis.

CONCLUSION

HCV infection is positively associated with gallstone formation especially in those with cirrhosis patients.

Association between the APOB XbaI and EcoRI polymorphisms and lipids in Chinese: a meta-analysis

Background

No previous meta-analysis was to report the association between the apolipoprotein B (APOB) XbaI and EcoRI polymorphisms and serum lipids in Chinese. We performed the study to investigate their potentially association.

Methods and Results

Studies in English and Chinese were found via a systematic search of Pubmed, Embase, CNKI and Wanfang databases. The dominant genetic model and random-effects model were used to pool data from individual studies. As a result, a total of 30 articles with 5611 subjects for XbaI and 2653 subjects for EcoRI were included in the current study. For the XbaI polymorphism, overall, subjects carrying X+ allele were significantly associated with higher TC,TG and LDL compared with X-X- genotype (Pvalue =0.0006, OR (95 %) = -0.55 (-0.86,-0.23); Pvalue = 0.0004, OR (95 %) = -0.30 (-0.47,-0.14); (Pvalue = 0.05, OR (95 %) = -0.23(-0.46,-0.00), respectively). Similar results were observed in the subgroups of Han, healthy individuals (HT), coronary heart disease (CHD), cerebral infarction (CI), and cholelithiasis. For HDL, positive association between X+ allele with Lower lipid value was found in CHD and CI subgroups. For EcoRI polymorphism, overall, the E- allele carriers were found to be obviously linked with elevated LDL and lower HDL compared with E + E+ genotype (Pvalue = 0.02,OR (95 %) = -0.27 (-0.49,-0.05); Pvalue = 0.01, OR (95 %) = 0.17 (0.03, 0.30), respectively). TC was significantly high in subjects carrying E- allele in the subgroup of hyperlipidemia. No evidence of publication bias was observed.

Conclusions

The two genetic variants of APOB may be associated with serum lipids in Chinese.

Association of C7673T polymorphism in apolipoprotein B gene with ischemic stroke in the Chinese population: a meta-analysis

BACKGROUND

Epidemiological studies have evaluated the association between the C7673T polymorphism in apolipoprotein B (apoB) gene and ischemic stroke (IS), but the results are still debatable even in the Chinese population. This meta-analysis was therefore designed to clarify these controversies.

METHODS

All of the relevant studies were identified from PubMed, Embase, Chinese National Knowledge Infrastructure database and Chinese Wanfang database up to 31 October 2014. Statistical analyses were conducted with Revman 5.2 and STATA 12.0 software. Odds ratio (OR) with 95% confidence interval (CI) values were applied to evaluate the strength of the association. A fixed or random effect model was selected for pooling data based on the heterogeneity test. Publication bias was assessed by Begg's test and Egger's test.

RESULTS

A significant association was found between the C7673T polymorphism in apoB gene and IS under the heterozygous genetic model (OR = 1.868, 95% CI = 1.160-3.007) and the allelic genetic model (OR = 1.742, 95% CI = 1.294-2.346), respectively. In the subgroup analysis by the geographic region, T allele could increase the risk of IS in northern Chinese (OR = 2.359, 95% CI: 1.425-3.907), but not in southern Chinese individuals (OR = 1.485, 95% CI: 0.778-2.832). Further stratification for source of controls showed that statistical significance was found among the population-based studies.

CONCLUSION

Our meta-analysis revealed that C7673T polymorphism in apoB gene was significantly associated with increased IS risk in the Chinese population.

The APOB gene polymorphism in the pathogenesis of gallstone disease in pre- and postmenopausal women

Aim of the study

The decrease in estrogen levels in the postmenopausal period changes the lipid profile by the expression of hepatic genes related to metabolism of cholesterol and bile acid synthesis that could be important in the pathogenesis of cholelithiasis. The aim of the study was to determine the APOB gene 7673C>T and 12669G>A polymorphisms in the pathogenesis of gallstones and analysis of the composition of gallstones in pre- and postmenopausal women.

Material and methods

The study group consisted of 94 women qualified to the laparoscopic cholecystectomy while the control group consisted of 81 women in whom gallstones and other changes in the bile ducts were excluded. Gallstones composition analysis was performed using commercially available assays. The prevalence of the APOB gene polymorphisms was determined using the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP).

Results

When assessing the composition of gallstones in pre- and postmenopausal women, we observed differences in the studied parameters. Analysis of genetic variants of APOB gene 7673C>T and 12669G>A polymorphisms showed no significant statistical differences between studied groups and controls.

Conclusions

Analysis of 7673C>T and 12669G>A polymorphisms showed no relationship between specific genetic variants and the risk of gallstones in pre- and postmenopausal women, pointing to the fact that the investigated polymorphisms are not relevant as prognostic factors in gallstone disease in the Caucasian population. Because of the possible contribution of a variety of factors in gallstones pathogenesis the studies are required to take account of additional environmental factors, what may indicate different occurrence between investigated polymorphisms, gallstone disease development and gallstones composition in Caucasians.

No association of apolipoprotein B gene polymorphism and blood lipids in obese Egyptian subjects

BACKGROUND

Several environmental and genetic factors are associated with high levels of lipids in obese patients. Apolipoprotein B (ApoB) is the major protein component of low-density lipoproteins (LDL), very-low density lipoproteins (VLDL) and chylomicrons and plays a central role in lipid metabolism. Several apoB restriction fragment length polymorphisms (XbaI, EcoRI, MspI) have been reported to be associated with variation in lipid levels and obesity. To date, no data are available on the relationship between XbaI polymorphism and lipid levels in Egyptian populations. Following clinical profiling, 178 obese (body mass index [BMI] >25 kg/m(2)) and 178 age-matched non-obese (BMI ≤ 25 kg/m(2)) subjects were included in this case-control study. All samples were analysed for total cholesterol, triglycerides and HDL-cholesterol. Genetic analysis of apoB XbaI (X) was performed using Polymerase Chain Reaction-Restriction Fragment Length polymorphism (PCR-RFLP). The aim of this study was to assess the association of apoB XbaI gene polymorphism (X) and lipid profiles in obese and non-obese Egyptian populations.

RESULTS

Obese subjects demonstrated significantly higher values of waist-to-hip ratio, blood pressure, and total lipid. However, in our sample we did not find significant differences in apoB XbaI gene polymorphism (X) genotype or allele frequencies. Moreover, none of the studied lipid parameters showed any association with the gene polymorphism.

CONCLUSION

This study reveals no significant association of apoB XbaI gene polymorphism (X) with obesity or lipid profiles in an Egyptian population.

Correlation between the Xba I polymorphism of apoB gene and serum lipid profiles in Li ethnic group

OBJECTIVE

To study correlation between the Xba I polymorphism of apoB gene and plasma lipid profiles in Li ethnic group.

METHODS

Total 151 cases of healthy Li people were recruited randomly by cluster sampling and 200 Han people were recruited as control; blood was drawn to analyze Xba I polymorphism distribution of apoB gene and serum lipid levels.

RESULTS

There were lower serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) levels in serum of Li people; while, high density lipoprotein cholesterol (HDL-C), X-/X+ genotype and X+ allele frequencies exhibited higher levels than Han people. Interestingly, HDL-C level was reduced, while LDL-C level was enhanced in subjects carrying heterozygous (X-/X+) genotype compared to homozygous (X-/X-) genotype. Additionally, there were no difference in serum level of triglyceride, TC, apoprotein A (apo A) and apoprotein B (apo B) between Li and Han people, the same results were showed between X-/X+ and X-/X- genotype carriers.

CONCLUSIONS

Xba I polymorphism of apoB gene is correlated to the profiles of serum lipid level, X-/X+ genotype carriers are phenotyped with higher LDL-C level and lower level of HDL-C in Li ethnic group.

Association of apolipoprotein B XbaI gene polymorphism and lipid profile in northern Indian obese

BACKGROUND:

Over the last few decades, obesity, diabetes, and hypertension have become main health evils. The health problems of obesity are well-recognized. However, the fact that all obese individuals are not at the same risk of developing a disease is also recognized. The apolipoprotein B (APOB) plays a central role in lipid metabolism. So we compare the association of APOB XbaI gene polymorphism and lipid profile total in obese north Indian population.

MATERIALS AND METHODS:

A total of 132 obese (body mass index [BMI] >25 kg/m²) and 132 age matched non-obese (BMI ≤ 25 kg/m²) subjects were studied after taking detailed clinical profile. Lipid profile in serum/plasma was done using commercial kits. Genetic analysis of APOB XbaI was done using Polymerase Chain Reaction-Restriction Fragment Leanth polymorphism (PCR-RFLP).

STATISTICAL ANALYSIS:

Statistical analysis was performed by Statistical Package for the Social Sciences (SPSS) (version 11.5) software (IBM Corporation). All continuous variables were expressed as mean ± SD and tested by analysis of variance test. Comparisons of categorical variables were assessed using χ² tests or Fisher's exact test. P < 0.05 was considered as significant.

RESULTS:

Analysis showed that obese subjects had significantly higher value of the waist-to-hip ratio, blood pressure (systolic and diastolic), and lipid profile. In APOB XbaI gene polymorphism, we did not find significant differences in genotype or allele frequencies. Moreover, none of the studied metabolic parameters (lipid profile) showed any association with the gene polymorphism.

CONCLUSIONS:

Study reveals no considerable association of APOB XbaI gene polymorphism with obesity and lipid profile in north Indians.

Genetics of gallstone disease

Gallstone disease (GSD) is one of the most common biliary tract disorders worldwide. The prevalence, however, varies from 5.9-21.9% in Western society to 3.1-10.7% in Asia. Most gallstones (75%) are silent. Approximately half of symptomatic gallstone carriers experience a second episode of biliary pain within 1 year. These individuals are at increased risk of developing acute cholecystitis, acute cholangitis, and biliary pancreatitis. As can be expected, these complications burden health care systems because of their invasive nature and surgical cost. Factors that contribute to gallstone formation include supersaturation of cholesterol in bile, gallbladder hypomotility, destabilization of bile by kinetic protein factors, and abnormal mucins. Epidemiologic studies have implicated multiple environmental factors and some common genetic elements in gallstone formation. Genetic factors that influence gallstone formation have been elaborated from linkage studies of twins, families, and ethnicities. Accumulating evidence suggests that genetic factors play a role in GSD.

The effects of serum cholesterol, LDL, and HDL levels on gallstone cholesterol concentration

OBJECTIVE

Gallbladder stones are common in the Western world, and 70% to 80% of gallstones are cholesterol stones. This study investigates the effects of serum cholesterol, LDL, and HDL levels on gallstone cholesterol concentration.

METHODOLOGY

The gallstones of 75 patients with cholelithiasis were examined using spectrophotometry.

RESULTS

High serum cholesterol and LDL levels were associated with high cholesterol stone rates (86.7% vs. 40.0%, P < 0.001; 75.0% vs. 48.9%, P < 0.05, respectively). Similarly, high serum cholesterol and LDL levels were correlated with high gallbladder stone cholesterol concentrations (63.6% vs. 44.4%, P < 0.001; 62.3% vs. 46.0%, P < 0.001, respectively). In contrast, low serum HDL levels do not seem to affect the occurrence of gallbladder cholesterol stones (60.0% vs. 58.3%, respectively, P > 0.05) or gallbladder stone cholesterol concentrations (50.8% vs. 52.4%, respectively, P > 0.05).

CONCLUSION

The relationship between cholesterol, LDL, and HDL levels and cholesterol gallstone formation is multifactorial and complex and is also dependent on other individual properties.

ApoB-100, ApoE and CYP7A1 gene polymorphisms in Mexican patients with cholesterol gallstone disease

AIM: To determine the possible association of the ApoB-100 (XbaI), ApoE (HhaI) and CYP7A1 (BsaI) gene polymorphisms, with the development of cholesterol gallstone disease (GD) in a Mexican population.

METHODS: The polymorphisms were analyzed by polymerase chain reaction followed by restriction fragment length polymorphism, in two groups matched by ethnicity, age and sex: patients with GD (n = 101) and stone-free control subjects (n = 101).

RESULTS: Allelic frequencies in patients and controls were: 34.16% vs 41.58% (P = 0.124) for X+ of ApoB-100; 4.46% vs 5.94% (P = 0.501) for E2, 85.64% vs 78.22% (P = 0.052) for E3, 9.90% vs 15.84% (P = 0.075) for E4 of ApoE; and 25.74% vs 27.72% (P = 0.653) for C of CYP7A1. Differences in genotypic frequencies between the studied groups were not significant (P < 0.05).

CONCLUSION: These results demonstrated that no association exists between the studied polymorphisms and cholelithiasis in this high prevalent population.

The genetic background of gallstone formation: an update

Gallstone disease is one of the most prevalent gastrointestinal diseases with a substantial burden to health care systems that is expected to increase in ageing populations at risk. This review summarizes recent data on the genetic background of cholesterol gallstones and the role of biliary lipid composition. Three previously unknown non-synonymous mutations in the ABCB4 gene encoding the hepatobiliary phospholipid-flippase MDR3 are presented.

XbaI polymorphisms of apolipoprotein B gene: Another risk factor of gallstone formation after radical gastrectomy

AIM: To prospectively investigate the association between the XbaI polymorphisms of apolipoprotein B (APOB) gene and gallstone formation following gastrectomy.

METHODS: The study was conducted between January 2005 and December 2006. A total of 186 gastric cancer patients who had undergone radical gastrectomy were grouped according to XbaI polymorphisms of APOB gene (X⁺X^- group, n = 24 and X^-X^- group, n = 162) and compared. The XbaI polymorphisms of APOB gene were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS: The incidence of gallstone was significantly higher in the X⁺X^- group than in the X^-X^- group [54.2% vs 9.3%, RR = 5.85 (2.23-15.32), P < 0.001]. The serum levels of total cholesterol (TC) and low-density lipoprotein (LDL) were higher in the X⁺X^- than in the X^-X^- group (4.02 ± 1.12 vs 3.48 ± 0.88, P = 0.004 before surgery and 3.88 ± 1.09 vs 3.40 ± 0.86, P = 0.008 after surgery). LDL was 2.21 ± 0.96 vs 1.89 ± 0.84 (P = 0.042) before surgery and 2.09 ± 0.95 vs 1.72 ± 0.85 (P = 0.029) after surgery in the two groups. No relationship was found between XbaI polymorphisms and gallbladder motility.

CONCLUSION: In Chinese patients after radical gastrectomy, X⁺ allele of APOB gene is another risk factor for the development of gallstone besides the gallbladder motility disorder after surgery.

Decreased NPC1L1 expression in the liver from Chinese female gallstone patients

BACKGROUND

Cholesterol gallstone disease is a very common disease in both industrialized and developing countries. Many studies have found that cholesterol gallstones are more common in women than men. The molecular mechanisms underlying the relationship between female gallstone disease and hepatic sterol transporters are still undergoing definition and have not been evaluated in humans.

AIMS

The aim of this study is to probe for underlying hepatic molecular defects associated with development of gallstones in female.

METHODS/RESULTS

Fifty-seven nonobese, normolipidemic Chinese female gallstone patients (GS) were investigated with 12 age- and body mass index-matched female gallstone-free controls (GSF). The bile from the female GS had higher cholesterol saturation than that from the female GSF. The hepatic NPC1L1 mRNA levels were lower in female GS, correlated with SREBP2 mRNA. NPC1L1 downregulation was confirmed at protein levels. Consistently, immunohistochemistry showed decreased NPC1L1 expression in female GS.

CONCLUSIONS

The decreased hepatic NPC1L1 levels in female GS might indicate a downregulated reabsorption of biliary cholesterol in the liver, which, in turn, leads to the cholesterol supersaturation of bile. Our data are consistent with the possibility that hepatic NPC1L1 may be mediated by SREBP2.

Disparities in allele frequencies and population differentiation for 101 disease-associated single nucleotide polymorphisms between Puerto Ricans and non-Hispanic whites

Background

Variations in gene allele frequencies can contribute to differences in the prevalence of some common complex diseases among populations. Natural selection modulates the balance in allele frequencies across populations. Population differentiation (F_ST) can evidence environmental selection pressures. Such genetic information is limited in Puerto Ricans, the second largest Hispanic ethnic group in the US, and a group with high prevalence of chronic disease. We determined allele frequencies and population differentiation for 101 single nucleotide polymorphisms (SNPs) in 30 genes involved in major metabolic and disease-relevant pathways in Puerto Ricans (n = 969, ages 45–75 years) and compared them to similarly aged non-Hispanic whites (NHW) (n = 597).

Results

Minor allele frequency (MAF) distributions for 45.5% of the SNPs assessed in Puerto Ricans were significantly different from those of NHW. Puerto Ricans carried risk alleles in higher frequency and protective alleles in lower frequency than NHW. Patterns of population differentiation showed that Puerto Ricans had SNPs with exceptional F_ST values in intronic, non-synonymous and promoter regions. NHW had exceptional F_ST values in intronic and promoter region SNPs only.

Conclusion

These observations may serve to explain and broaden studies on the impact of gene polymorphisms on chronic diseases affecting Puerto Ricans.

Gallstone disease: from genes to evidence-based therapy

The number of gallstone patients is increasing in ageing populations with a high prevalence of metabolic syndrome and obesity. Recently variants of hepatic ATP binding cassette transporters have been identified as genetic susceptibility factors for gallstone disease, pointing to novel means for risk assessment and prevention. Although laparoscopic cholecystectomy is the mainstay of therapy for symptomatic gallbladder stones, the clinical management of gallstone disease is changing rapidly, with an increase in day case surgery and the advent of transluminal endoscopic surgery. Here, we summarize the molecular and genetic mechanisms of gallstone formation as well as the current evidence-based algorithms for diagnosis and therapy of gallbladder and bile duct stones.

Higher alleles of apolipoprotein B gene 3' VNTR: Risk for gallstone disease

BACKGROUND

Imbalance in cholesterol homeostasis may lead to gallstone disease. Apolipoprotein B is sole component of low-density lipoprotein and plays an important role in cholesterol metabolism. The present study was carried out to explore the association of APOB 3' VNTR, exon 26 XbaI and signal peptide insertion/ deletion polymorphisms with gallstone disease. 214 ultrasonographically proven gallstone patients and 322 healthy, age and sex matched controls were taken for the study. Genotyping was done using PCR followed by polyacrylamide gel electrophoresis for VNTR and insertion/ deletion analysis. For APOB XbaI polymorphism PCR product was digested with XbaI restriction enzyme, followed by agarose gel electrophoresis. All statistical analyses were done using SPSS v11.5. Higher repeat alleles of APOB 3' VNTR polymorphism were more frequent in gallstone patients than in controls. Alleles with more than 57 repeats were present only in patient group. Long (L) alleles with repeat higher than 49, were significantly higher (P=0.000; OR=3.705, 95% CI 2.577-5.326) and medium (M) alleles were lower (P=0.000; OR=0.406, 95% CI 0.304-0.542) in patients than in controls. To nullify the effect of gender, data was further stratified into male and female population. APOB 3' VNTR, L alleles were imposing risk and M alleles were protective in both male and female population. APOBXbaI and insertion/deletion polymorphisms were not found to be associated with the gallstone disease. Longer alleles of APOB 3' VNTR occur more frequently in gallstone patients, and may be an important risk factor for the development of gallstone disease. APOB XbaI and signal peptide insertion/deletion polymorphisms may not be contributing to the risk for gallstone disease.

Association of polymorphisms at restriction enzyme recognition sites of apolipoprotein B and E gene with dyslipidemia in children undergoing primary nephrotic syndrome

BACKGROUND

Dyslipidemia, a common complication, is very prevalent in children with primary nephrotic syndrome (PNS). Recent studies have shown that genetic basis may be involved in the onset of HLP secondary to PNS. ApoB and E have been identified as the important candidate genes for lipid abnormalities.

OBJECTIVE

To investigate the association of apolipoprotein B (apoB) and E (apoE) genetic polymorphisms (Xba I, EcoR I, Msp I, and Hha I) with parameters describing the serum lipid profiles in children undergoing PNS.

METHODS

Genomic DNA was extracted from 250 children diagnosed with PNS and 200 healthy controls with neither allergic nor renal disease. ApoB (Xba I, EcoR I, and Msp I) and apoE (Hha I) genotypes were determined by PCR-restriction fragment length polymorphism (RFLP) analysis. The fasting serum lipoprotein (a) [Lp(a)], total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), apolipoprotein A1 (apoA1), apoB, and total protein from a 24-h urine sample were measured.

RESULTS

No significant differences in genotypes and alleles frequencies were observed for the apoB Xba I, EcoR I, Msp I and the apoE Hha I restriction sites in PNS patients as compared to controls (P > 0.05). Patients and controls with X + allele exhibited significantly higher serum levels of Lp(a), TC, nonHDL-C, LDL-C, LDL-C/HDL-C ratio, and apoB than that with X- allele (P < 0.05), whereas for apoA1/B ratio the opposite was found (P < 0.01). E-/E- carriers had significantly higher Lp(a), TC, HDL-C, and apoA1 concentrations than did E+/E- or E+/E+ carriers in control group (P < 0.05). Healthy children carrying the rare EcoR I allele had higher mean Lp(a), TC, and HDL-C levels than homozygotes for E+ (P < 0.05). Higher Lp(a) serum concentrations were observed in patients with E- allele (P < 0.05). No significant differences in lipid parameters were determined for the apoB Msp I and apoE Hha I the polymorphisms study (P > 0.05). When genetic variations were compared with urinary protein excretion, the Xba I X- allele was more frequent in patients with elevated proteinuria (P < 0.01).

CONCLUSION

Presence of Xba I X+ allele and/or EcoR I E- at the apoB gene may be risk factors for lipid abnormalities secondary to childhood PNS.

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

PURPOSE OF REVIEW

Chronic biliary diseases are due to complex interactions between environmental and genetic factors. Here we summarize the current knowledge of genetic factors that contribute to common biliary diseases, focusing on gallstones and carcinogenesis, and review the recent association studies.

RECENT FINDINGS

Since most studies were based on small sample sizes, replication of the findings is mandatory. Recently a large twin study confirmed a genetic predisposition to gallstones and a genome-wide association scan identified the hepatocanalicular cholesterol transporter ABCG8 as the common susceptibility factor for gallstone disease. Genetic studies in patients with cholangiocarcinoma indicate that genes controlling the metabolism and transport of xenobiotics or modulating chronic inflammation may determine individual susceptibility.

SUMMARY

Genetic studies have identified the first susceptibility factors for gallstones and biliary tract cancers, but most results have yet to be replicated. In the future, genome-wide studies in different populations are likely to identify the entire set of genes contributing to chronic biliary diseases. Since the disease phenotypes result from the manifestation of susceptibility factors under the influence of environmental triggers, the discovery of these genes will open avenues to control environmental challenges and lead to novel strategies for risk assessment ('gene signatures') and prevention.

Increased expression of LXR alpha, ABCG5, ABCG8, and SR-BI in the liver from normolipidemic, nonobese Chinese gallstone patients

Cholesterol supersaturation of bile is one prerequisite for gallstone formation. In the present study of Chinese patients with gallstones, we investigated whether this phenomenon was correlated with the hepatic expression of genes participating in the metabolism of cholesterol and bile acids. Twenty-two nonobese, normolipidemic patients (female-male, 11:11) with gallstones were investigated with 13 age- and body mass index-matched gallstone-free controls (female-male, 10:3). The bile from the gallstone patients had higher cholesterol saturation than that from the controls. The mRNA levels of ABCG5, ABCG8, and liver X receptor alpha (LXRalpha) in the gallstone patients were increased by 51, 59, and 102%, respectively, and significantly correlated with the molar percentage of biliary cholesterol and cholesterol saturation index (CSI). The mRNA and protein levels of the hepatic scavenger receptor class B type I (SR-BI) were increased, and a significant correlation was found between the protein levels and the CSI. No differences were recorded between the two groups concerning the hepatic synthesis of cholesterol, bile acids, and esterification of cholesterol. Our results suggest that the upregulation of ABCG5/ABCG8 in gallstone patients, possibly mediated by increased LXRalpha, may contribute to the cholesterol supersaturation of bile. Our data are consistent with the possibility that increased amounts of biliary cholesterol may originate from plasma HDL cholesterol by enhanced transfer via SR-BI.

Haplotype analysis of signal peptide (insertion/deletion) and XbaI polymorphisms of the APOB gene in gallbladder cancer

PURPOSE

The incidence of gallbladder cancer (GBC) is usually paralleled by the prevalence of gallstone disease, and genes of cholesterol metabolism have been implicated in gallstone disease. The XbaI and insertion/deletion (ins/del) polymorphism of Apolipoprotein B (APOB) appears to influence cholesterol homoeostasis and possibly risk for gallstone disease. We examined the effect of these polymorphisms individually as well as their haplotypes on GBC and gallstone patients in North Indian population.

METHODS

The study comprises 123 consecutive cases of proven GBC, 172 cases of gallstone and 232 healthy subjects of similar age and sex. The genomic DNA was extracted from peripheral blood leucocytes and genotyping was performed using polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism.

RESULTS

In a case-control study, APOB XbaI and ins/del polymorphisms were not significantly associated with risk of GBC. Using the expectation maximization algorithm, four haplotypes were obtained, and haplotype X(+),D was found to be significantly higher in GBC patients without stone in comparison with healthy subjects [odds ratio (OR) 2.9, 95% confidence interval 1.2-6.6 P=0.012].

CONCLUSIONS

The X(+),D haplotype of APOB is associated with increased risk for development of GBC and the risk is not modified in the presence of gallstones.

Apolipoprotein B (APOB) Gene Polymorphism in Patients with Gallbladder Disease

Cholelithiasis is one of the most prevalent gastroenterological diseases, precipitated mainly by environmental factors. However, twin studies provided strong evidence for a role of genetic factors in the disease pathogenesis. An association between plasma lipoprotein levels and gallstone disease (GSD) was presented. Apolipoprotein B is an essential structural component of triglyceride-rich lipoprotein particles and plays an important role in the maintenance of cholesterol homeostasis in mammals. Various studies have shown a relationship between APOB gene polymorphisms and lipoprotein levels, but only few investigated a potential association between APOB polymorphism and GSD, giving contrary results. In the current study, an association between common polymorphisms in APOB gene (T2488T and E4154K) and cholesterol gallstone disease was examined. Two hundred and forty patients of Caucasian origin suffering from cholelithiasis, as well as 217 healthy individuals, were included in the study. Patients were genotyped for two single nucleotide polymorphisms (SNPs) in APOB gene: 2488C>T (XbaI), and 4154G>A (EcoRI) using PCR-RLFP method. The resulting analysis has shown that polymorphic loci in positions 2488 and 4154 in APOB gene are in full linkage in a Polish population and form only three haplotypes: 2488C-4154G, 2488T-4154G and 2488C-4154A. Frequency and distribution of 2488C>T alleles did not differ significantly between patients and controls. The 4154G allele has been found to be associated with GSD (p=0.001). A risk of gallstone formation was reduced in 4154AA homozygotes (OR=0.25, p=0.009) and heterozygous individuals (OR=0.63, p=0.03) as compared to 4154GG homozygotes. Additionally, 2488C-4154A haplotype was identified as a protective factor against GSD (p=0.04). Our results suggest that SNPs in APOB, potentially considered as one of lith genes as well as certain haplotypes, may be risk factors for GSD.

Biliary Tract Cancer

This chapter reviews the epidemiology of biliary tract cancer. Many etiologic leads for biliary tract cancer have come from clinical observations, autopsy series, and descriptive epidemiologic studies. While a significant fraction of these tumors are related to gallstones (cholelithiasis), information on other risk factors is limited, due to the rarity of the tumors, the often rapidly fatal course, and the small number of epidemiologic studies conducted to date. Because the three anatomic categories of biliary tract cancer have distinct epidemiologic patterns and molecular changes, including somatic mutations and loss of heterozygosity (LOH), it has been suggested that the causal factors vary by subsite.

Investigation of the Lith1 candidate genes ABCB11 and LXRA in human gallstone disease

Genetic susceptibility in the causation of gallbladder diseases was recognized as early as 1937. A major gallstone susceptibility locus (Lith1) was identified in 1995 by quantitative trait locus mapping in mice. Two attractive positional and functional candidate genes in LXRA and ABCB11 are located in this interval. ABCB11 is associated with progressive familial cholestasis. This study was undertaken to investigate LXRA and ABCB11 as candidate genes for gallstone disease in humans. Eight hundred and ten patients who underwent cholecystectomy for symptomatic gallstone disease (median age of onset, 50 years) were compared with 718 sex-matched control individuals. Control individuals were sonographically free of gallstones. Haplotype tagging and all known coding single nucleotide polymorphisms (SNPs) were genotyped for ABCB11 (n=29) and LXRA (n=10). The investigated high-risk patient sample provides a power of greater than 80% for the detection of odds ratios down to 1.55. No evidence of association of the two genes in the single point tagging markers, coding variants or in the sliding window haplotype analysis was detected (all nominal single-point P values>or=.08). In conclusion, in the investigated German sample, no evidence of association of ABCB11 and LXRA to gallstone susceptibility was detected. The gallstone trait is not allelic to progressive familial cholestasis at the ABCB11 locus. Systematic fine mapping of the Lith1 region is required to identify the causative genetic variants for gallstone in mice and humans.

Gallstone disease. Pathogenesis of gallstones: A genetic perspective

Cholelithiasis is one of the most prevalent gastroenterological diseases, imposing a huge economic burden on health-care systems. Gallbladder stones form when the concentration of cholesterol or bilirubin exceeds the solubility in the bile salt and phospholipid-rich bile. The physiology of biliary lipid secretion by a number of specialized transport proteins has recently been elucidated, and underlying genetic defects in these proteins have been identified as susceptibility factors for gallstone disease. Recent studies of identical twins and family strongly support the idea of a genetic component to gallstone disease. Epidemiological studies in high-risk populations indicate that gallstone formation is caused by multiple environmental influences and common genetic factors and their interactions. Monogenic subtypes of cholelithiasis, such as biliary lipid transporter deficiencies, appear to be rare. The characterization of lithogenic genes in knockout and transgenic mice, and the identification of many gallstone susceptibility loci in inbred mice, provide the basis for studies of the corresponding genes in patients with gallstones. The transfer of findings from mouse genetics to the bedside might lead to new strategies for individual risk assessment and reveal molecular targets for the development of new treatment strategies.

Correlations of chronic hepatitis C virus infection with Xba I polymorphism of apolipoprotein B gene and serum lipid metabolism

AIM: To investigate the Xba I locus polymorphisms of apolipoprotein B (Apo B) gene and their internal correlations with chronic hepatitis C virus infection and serum lipid metabolism.

METHODS: Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used to analyze the genotype of the Apo B gene in 77 patients and 62 controls, according to the design of case control study. Meanwhile, the blood samples were analyzed for hepatic function and serum lipid by automatic biochemistry analyzer.

RESULTS: The frequencies of X⁺X^- and X^-X^- of Xba I locus polymorphism were different between the patients and the controls and the frequency of X⁺ allele in the patients was lower than that in the controls (0.071 vs 0.121, P = 0.136), but no statistical significance was not found. The frequency of X⁺ allele in patients with HCV RNA≥80 000 copies/L was significantly lower than that with HCV RNA<80 000 copies/L (0.048 vs 0.179, P = 0.035). Furthermore, the levels of Apo B in the patients of X⁺X^- genotype were significantly higher than those in the patients of X^-X^- genotype (P = 0.019). The serum levels of low density lipoprotein (LDL) and Apo B were negatively correlated with serum HCV RNA levels in patients with chronic hepatitis C (r = -0.460, P = 0.016; r = -0.538, P = 0.005, respectively), and the correlation with serum alanine aminotransferase (ALT) levels was not found.

CONCLUSION: The Xba I locus polymorphism of Apo B gene is not correlated with susceptibility of Chinese people to HCV, but it may affect the HCV viral load in patients with chronic hepatitis C. The variation of X⁺ allele may affect serum Apo B levels in patients with chronic HCV infection. The serum levels of LDL and Apo B are closely correlated with serum HCV RNA levels in patients with chronic hepatitis C.

Mechanisms of disease: the genetic epidemiology of gallbladder stones

Cholelithiasis is one of the most prevalent and most expensive gastroenterologic diseases. It belongs to the group of complex metabolic disorders that affect humans, and its critical pathogenic mechanisms are not well defined. As a result, primary or secondary prevention strategies are sparse, and the only effective treatment is cholecystectomy. Here we provide an update on the molecular pathogenesis of gallbladder stones, evidence supporting the hypothesis that genetic factors are key elements predisposing to gallstones, and progress in human genetic studies of cholesterol stones. Data from recent identical twin, family and linkage studies provide conclusive evidence for a strong genetic component to gallstone disease. Furthermore, epidemiologic studies in at-risk populations indicate that gallstone formation is caused by multiple environmental influences and common genetic factors and their interactions. By contrast, monogenic subtypes of cholelithiasis, such as ATP-binding-cassette transporter deficiencies, appear to be rare. The summary of human association studies illustrates that distinct common gene variants might contribute to gallstone formation in different ethnic groups. The characterization of lithogenic genes in knockout and transgenic mice and the identification of many gallstone-susceptibility loci in inbred mice provide the basis for studies of the corresponding genes in patients with gallstones. The transfer of findings from mouse genetics to the bedside might lead to new strategies for individual risk assessment and reveal novel molecular targets for prevention and medical therapies.

Reduced susceptibility to cholesterol gallstone formation in mice that do not produce apolipoprotein B48 in the intestine

It has been found that polymorphisms in the apolipoprotein (APO)-B gene are associated with cholesterol gallstones in humans. We hypothesized that APO-B plays a major regulatory role in the response of biliary cholesterol secretion to high dietary cholesterol and contributes to cholesterol gallstone formation. In the present study, we investigated whether lack of expression of intestinal Apob48 or Apob100 reduces susceptibility to cholesterol gallstones by decreasing intestinal absorption and biliary secretion of cholesterol in male mice homozygous for an "APO-B48 only" allele (Apob(48/48)), an "APO-B100 only" allele (Apob(100/100)), or a wild-type APO-B allele (Apob+/+) before and during an 8-week lithogenic diet. We found that cholesterol absorption was significantly decreased as a result of the APO-B48 deficiency in Apob(100/100) mice compared with wild-type and Apob(48/48) mice, regardless of whether chow or the lithogenic diet was administered. Consequently, hepatic cholesterol synthesis was significantly increased in Apob(100/100) mice compared with wild-type and Apob(48/48) mice. On chow, the APO-B100 deficiency in Apob(48/48) mice with reduced plasma levels of LDL/VLDL--but not HDL cholesterol--induced relative hyposecretion of biliary bile salts and phospholipids accompanying normal biliary cholesterol secretion. Compared with Apob(48/48) and wild-type mice, lithogenic diet-fed Apob(100/100) mice displayed significantly lower secretion rates of biliary cholesterol, but not phospholipid or bile salts, which results in significant decreases in prevalence rates, numbers, and sizes of gallstones. In conclusion, absence of expression of intestinal Apob48, but not Apob100, reduces biliary cholesterol secretion and cholelithogenesis, possibly by decreasing intestinal absorption and hepatic bioavailability.

Gallstone disease in non-alcoholic fatty liver: prevalence and associated factors

BACKGROUND

Insulin resistance is a risk factors for non-alcoholic fatty liver disease (NAFLD) and for gallstone disease (GD). Aims of the present study were to assess the prevalence of and factors associated with GD in unselected patients with NAFLD.

METHODS

A total of 161 consecutive patients with NAFLD diagnosed through compatible ultrasonography in the absence of known etiologies of liver disease (in all patients) and/or confirmed histologically (in 61 patients), was studied. Gallstone disease was diagnosed through ultrasound scanning or on the basis of previous cholecystectomy. Anthropometric and biochemical variables and concurrent diseases were compared in 32 NAFLD-GD patients and in 129 NAFLD patients without GD (controls) according to gender.

RESULTS

The overall prevalence of GD was 19.88%, higher in female patients (P < 0.05), who were older (P < 001). The overall percentage of GD increased with age (P < 0.05). The GD patients had higher uric acid (men), total cholesterol and apolipoprotein B (apo-B) serum concentrations (women; P < 0.05); women also had a higher prevalence of hypertriglyceridemia (P < 0.05). The age-corrected odds ratio of having GD by tertiles increased significantly with increasing uric acid (men) and with increasing total cholesterol, triglycerides and apo-B (women). At univariate continuous analysis GD was associated with insulin 120 min and uric acid in male patients; and with body mass index, insulin 120 min, apo-B, total cholesterol and triglycerides in female patients. On multivariate analysis it was found that among these factors only uric acid in men and apo-B in women were independently associated with GD in NAFLD.

CONCLUSIONS

The prevalence of GD in NAFLD is more elevated than reported in the general population. The factors independently associated with GD in NAFLD are different from those reported in the general population and vary according to the gender.

Polymorphisms at cholesterol 7α-hydroxylase, apolipoproteins B and E and low density lipoprotein receptor genes in patients with gallbladder stone disease

AIM: To investigate the relationship between gallbladder stone disease (GSD) and single nucleotide polymorphisms of cholesterol 7α-hydroxylase (CYP7A) gene promoter, apolipoprotein (APO) B gene exon 26, APOE gene exon 4 or microsatellite polymorphism of low density lipoprotein receptor (LDLR) gene exon 18.

METHODS: Genotypes of CYP7A, APOB, APOE and LDLR genes were determined in 105 patients with GSD diagnosed by B-mode ultrasonography and 274 control subjects. Serum lipids were analyzed with HITACHI 7060 automaic biochemical analyzer.

RESULTS: Body mass index (BMI) was significantly higher in patients with GSD (24.47 ± 3.09) than in controls (23.50 ± 2.16). Plasma total cholesterol was lower in patients with GSD (4.66 ± 0.92 mmol/L) than in controls (4.91 ± 0.96 mmol/L), P < 0.01 after adjusted for age, sex and BMI. The significantly higher frequency of A allele of CYP7A gene polymorphism and X+ allele of APOB gene polymorphism was seen in GSD patients. Percentages of A allele in patients and controls were 62.86% and 54.38% (P < 0.05) and those of X+ allele 8.57% and 4.01% (P < 0.01). Subjects with A allele had significantly lower plasma total cholesterol and LDL cholesterol than subjects with CC homozygote. In a multiple variable logistic regression model, the BMI (OR = 1.13, 95%CI: 1.05-1.22), A allele (OR = 1.48, 95%CI: 1.05-2.09) and X+ allele (OR = 2.28, 95%CI: 1.14-4.59) were positively associated with GSD (P < 0.05). Plasma total cholesterol (OR = 0.69, 95%CI: 0.64-0.74) was negatively related to GSD (P < 0.05).

CONCLUSION: With an association analysis, it was determined that A allele of CYP7A gene and X+ allele of APOB gene might be considered as risk genes for GSD. These alleles are related with differences of serum lipids among subjects. Multiple-variable logistic regression model analysis showed that besides BMI, GSD was affected by polygenetic factors. But the mechanism for these two alleles responsible for GSD requires further investigations.

Genetic analysis of cholesterol gallstone formation: searching for Lith (gallstone) genes

The genetics of cholesterol cholelithiasis is complex because a number of interacting genes regulate biliary cholesterol homeostasis. Quantitative trait locus (QTL) analysis is a powerful method for identifying primary rate-limiting genetic defects and discriminating them from secondary downstream lithogenic effects caused by mutations of the primary genes. The subsequent positional cloning of such genes responsible for QTLs may lead to the discovery of pathophysiologic functions of Lith (gallstone) genes. In this review, we present a map of candidate genes for Lith genes that may determine gallstone susceptibility in mice. The physical-chemical, pathophysiologic, and genetic studies of Lith genes in bile, liver, gallbladder, and intestine will be crucial for elucidating the genetic mechanisms of cholesterol gallstone disease in mice and in humans. Because exceptionally close homology exists between mouse and human genomes, the orthologous human LITH genes can often be recognized after mouse genes are identified.

Implication of an AGT Haplotype in a Multigene Association Study With Pregnancy Hypertension

Several association studies of candidate genes for preeclampsia and essential hypertension have led to discordant results, partly because of small sample sizes. Using a large population-based sample of pregnant women, we conducted an association study of 10 polymorphisms in 9 genes and aimed (1) to validate 10 published associations with preeclampsia or essential hypertension, (2) to investigate candidate polymorphisms previously associated with preeclampsia for association with essential hypertension and similarly with polymorphisms previously associated with essential hypertension. From a prospective sample of 3391 nulliparous French Canadian pregnant women, we identified 180 cases of preeclampsia, 203 cases of essential hypertension that were matched with normotensive control subjects (n=310 and 357, respectively). Polymorphisms were genotyped by allele-specific PCR. Among our candidate polymorphisms, the Met allele of Thr174Met of AGT was associated with preeclampsia ( P =0.0033). Haplotype analysis revealed that the A-Met-Thr (G1035A-Thr174Met-Met235Thr) haplotype was associated with a 2.1-fold increased risk of preeclampsia (95% CI, 1.4 to 3.4; P =0.0008). In conclusion, we observed a strong association between a specific AGT haplotype and preeclampsia in our population, without replicating previous published associations with either preeclampsia or essential hypertension. Our data support a role for AGT in genetic susceptibility to preeclampsia.

Apolipoprotein B-100 XbaI gene polymorphism in gallbladder cancer

Genetic polymorphisms in the apolipoprotein B (apoB) gene have been reported to be associated with altered serum lipids and susceptibility to cholesterol gallstones (GS). Gallstones are among the well-known risk factors for carcinoma of the gallbladder (GBC). In the present study, the association between the XbaI polymorphism of the apo B gene was examined in patients with GBC and GS and in normal controls in a north Indian population. DNA samples from patients with GBC (n=153), GS (n=117) and healthy subjects (n=137) were analysed for the apoB- XbaI polymorphism by polymerase chain reaction followed by restriction fragment length polymorphism. The genotype X+/- was less frequent in patients with GBC (39.2%) than in those with GS (68.3%) and in normal subjects (66.4%; P<0.00001). In contrast, there was an increase in the homozygous X-/- genotype in patients with GBC (54.9%) as compared with those with GS (23.9%) and normal subjects (25.5%; P<0.00001). The frequency of the X- allele was found to be significantly increased in GBC patients with or without GS (odds ratio=2.3 and 1.7, respectively). We suggest that the apoB-XbaI gene polymorphism confers susceptibility to carcinoma of the gallbladder under specific environmental conditions.

Genetic background of cholesterol gallstone disease

Cholesterol gallstone formation is a multifactorial process involving a multitude of metabolic pathways. The primary pathogenic factor is hypersecretion of free cholesterol into bile. For people living in the Western Hemisphere, this is almost a normal condition, certainly in the elderly, which explains the very high incidence of gallstone disease. It is probably because the multifactorial background genes responsible for the high incidence have not yet been identified, despite the fact that genetic factors clearly play a role. Analysis of the many pathways involved in biliary cholesterol secretion reveals many potential candidates and considering the progress in unraveling the regulatory mechanisms of the responsible genes, identification of the primary gallstone genes will be successful in the near future.

Chromosomal organization of candidate genes involved in cholesterol gallstone formation: a murine gallstone map

Epidemiologic and family studies indicate that cholesterol gallstone formation is in part genetically determined. The major contribution to our current understanding of gallstone genes derives from animal studies, particularly cross-breeding experiments in inbred mouse strains that differ in genetic susceptibility to cholesterol gallstone formation (quantitative trait loci mapping). In this review we summarize how the combined use of genomic strategies and phenotypic studies in inbred mice has proven to be a powerful means of dissecting the complex pathophysiology of this common disease. We present a "gallstone map" for the mouse, consisting of all genetic loci that have been identified to confer gallstone susceptibility as well as putative candidate genes. Translation of the genetic loci and genes between mouse and human predicts chromosomal regions in the human genome that are likely to harbor gallstone genes. Both the number and the precise understanding of gallstone genes are expected to further increase with rapid progress of the genome projects, and multiple new targets for early diagnosis and prevention of gallstone disease should become possible.