Neuropeptide Y Y1 receptor polymorphism as a prognostic predictor in Japanese patients with IgA nephropathy.

BACKGROUND: Neuropeptide Y exhibits a vasoconstricting action and regulates systemic blood pressure as well as noradrenalin. There are 5 types of NPY receptors, Y1 - Y5, which were introduced by pharmacological differences. Recently, a single point mutation in the first intron of the NPY Y1 receptor (NPYY1R) was reported. SUBJECTS AND METHODS: In this study, we investigated the relationship between NPYY1R gene polymorphism and clinical characteristics in patients with IgA nephropathy using polymerase chain reaction and restriction fragment length polymorphism analysis. RESULTS: Distribution of the NPYY1R genotypes which were defined as YY, Yy and yy genotypes, did not differ between 60 normal control subjects and 68 patients with IgA nephropathy (15 : 36 : 9 versus 21 : 40 : 7, respectively). In IgA nephropathy patients, the incidence of hypertension and the rate of urinary protein excretion were slightly higher in the non-YY genotype than in the YY genotype group (23% versus 5% and 1.1 +/- 1.2 versus 0.6 +/- 0.4 g/24 h, p = 0.09 and p = 0.05, respectively). The reciprocal of the serum creatinine level was estimated to determine the deterioration in renal function during follow-up after the renal biopsy. The level was lower in the non-YY genotype than in the YY genotype group (-0.002 +/- 0.064 vs 0.033 +/- 0.053/month, respectively, p < 0.01). Multiple regression analysis for the reciprocal of the serum creatinine level revealed that the NPYY1R genotype was an effective variable (p < 0.01). CONCLUSION: In conclusion, we propose that the NPYY1R gene polymorphism may be a novel prognostic predictor in patients with IgA nephropathy.