Aim: Ezetimibe is known to target Niemann-Pick Type C1 Like1 (NPC1L1), a key protein in intestinal cholesterol absorption, and thus to decrease serum LDL-cholesterol (LDL-C) levels. The response of serum LDL-C levels to ezetimibe was reported to differe among NPC1L1 haplotypes.We analyzed NPC1L1 genotypes in Japanese and investigated differences in markers of cholesterol synthesis/absorption among the genotypes.
Methods: Blood samples were collected from 42 adult volunteers to measure markers of cholesterol synthesis (lathosterol) and absorption (sitosterol and campesterol) by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Based on a study by Hegele RA et al. in Canada, we selected three SNPs (1735 C>G, 25342 A>C and 27677 T>C (numbers relative to the transcription start site)) and analyzed them using PCR-RFLP.
Results: The frequencies of genotypes were as follows: 1735 C/G (46%)>C/C (35%)>G/G (19%), 25342 A/A (97%)>A/C (3%)>C/C (0%) and 27677 T/T (97%)>T/C (3%)>C/C (0%). Serum campesterol levels were significantly higher in the 1735 G/G group than 1735 C/G+C/C group, but lathosterol levels showed no significant differences between the genotypes.
Conclusion: Our results revealed differences in the frequency of the NPC1L1 polymorphism between Japanese and Canadians. In Japanese, the 1735 G/G group showed enhanced cholesterol absorption from the intestine, as compared to the 1735 C/G+C/C group.