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

Abstract

Aim: To investigate the relationship between gallbladder stone disease (GSD) and single nucleotide polymorphisms of cholesterol 7alpha-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 automatic 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.

Figure 1

Genotypes of CYP7A, apolipoproteins B, E and LDL receptor gene. A: CYP7A gene, M: DNA Marker: 1000, 750, 500, 300, 150 bp (Cat. G3161, Promega, Medison, WI, USA); lanes 1, 2: AA type; lanes 3-5: AC type; lane 6: CC type; lanes 7, 8: PCR products, B: Apolipoprotein B gene, M: DNA Marker: 1543, 994, 695, 515, 377, 237 bp (Cat. MG0781, SABC, Shanghai, China), lane 1, 3, 5, 6: X+/- type: 2, 4, 7: X-/- type. C: Apo E gene, M: pGEM 7zf(+)/Hae III DNA Marker (Cat. MG0861, SABC, Shanghai, China), from lanes 1-9: ε3/3, ε2/2, ε3/4, ε2/4, ε2/3, ε4/4, ε3/4, ε2/2, ε3/3 types. D: LDL receptor gene, M: pGEM 7zf (+)/Hae III DNA Marker, from lanes 1-6: CC, BC, AA, AC, BC and AB types.