Interaction of functional NPC1 gene Polymorphism with smoking on coronary heart disease

Background: The protein of Niemann-pick type C1 gene (NPC1) is known to facilitate the egress of cholesterol and other lipids from late endosomes and lysosomes to other cellular compartments. This study aims to investigate whether the genetic variation in NPC1 is associated with risk of coronary heart disease (CHD) and to detect whether NPC1 might interact with smoking on the risk of CHD. Methods: We performed a case-control study, including 873 patients with coronary heart disease (CHD) and 864 subjects without CHD as control. Polymorphisms of NPC1 gene were genotyped by polymerase chain reaction (PCR) -restriction fragment length polymorphism (RFLP). Results: A tag-SNP rs1805081 (+644A > G) in NPC1 was identified. The G allele of the +644 locus showed reduced risk of CHD than wild-type genotype in Chinese population (recessive model GG vs. AG+AA: odds ratio [OR] 0.647, 95% CI 0.428 to 0.980, P = 0.039; additive model GG vs. AG vs. AA: OR 0.847, 95% CI 0.718 to 0.998, P = 0.0471). Moreover in smokers, the G-allele carriers had reduced risk of CHD compared with A-allele carries (OR 0.552, 95% CI 0.311 to 0.979, P = 0.0421). Conclusions: The results of the present study suggest that NPC1 variants seem to be contributors to coronary heart disease occurrence in Chinese population. Moreover, in smokers, NPC1 variants seem to confer protection to coronary heart disease.