A leucine(7)-to-proline(7) polymorphism in the signal peptide of neuropeptide Y was not identified in the Japanese population

Objective: A Leu(7)-to-Pro(7) polymorphism exists in the signal peptide par t of prepro-neuropeptide Y (NPY) and this polymorphism is associated with h igh 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 stu dy was designed to test whether Japanese people had the Leu(7)-to-Pro(7) po lymorphism 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 cha in 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 cap illary electrophoresis sequencer. Results: All 102 young healthy Japanese subjects showed Leu(7)/Leu(7) but n ot Leu(7)/Pro(7) or Pro(7)/Fro(7) in the NPY signal peptide. Conclusions: The incidence of the Leu(7)-to-Pro(7) polymorphism in the sign al peptide of NPY was extremely low in Japanese people, suggesting that the polymorphism producing Pro(7) is not one of the genetic determinant factor s affecting serum cholesterol levels in Japanese people.