Objective: A Leu(7)-to-Pro(7) polymorphism exists in the signal peptide part of prepro-neuropeptide Y (NPY) and this polymorphism is associated with high serum cholesterol and LDL cholesterol levels in both Finnish and Dutch people. There was a significant difference in the allelic frequencies among populations with different genetic backgrounds. Therefore, the present study was designed to test whether Japanese people had the Leu(7)-to-Pro(7) polymorphism in the NPY signal peptide.
Methods: A total of 102 healthy Japanese volunteers supplied blood samples, from which leucocyte DNA was isolated. Primer pairs for the polymerase chain reaction (PCR) were made according to Karvonen et al. Direct sequencing of the PCR product was carried out by the dye terminator method using a capillary electrophoresis sequencer.
Results: All 102 young healthy Japanese subjects showed Leu(7)/Leu(7) but not Leu(7)/Pro(7) or Pro(7)/Pro(7) in the NPY signal peptide.
Conclusion: The incidence of the Leu(7)-to-Pro(7) polymorphism in the signal peptide of NPY was extremely low in Japanese people, suggesting that the polymorphism producing Pro(7) is not one of the genetic determinant factors affecting serum cholesterol levels in Japanese people.