A polymorphism in the gene for the atrial natriuretic peptide and diabetic nephropathy. Diabetic Nephropathy Study Group.

Atrial natriuretic peptide is involved in blood pressure regulation via its vasodilating and natriuretic actions. Since diabetic nephropathy and hypertension are closely related, ANP is a reasonable candidate gene for diabetic nephropathy (DN). We genotyped 410 patients with type I diabetes (without DN n = 307; with DN n = 103) and 658 patients with type II diabetes (without DN n = 464; with DN n = 194). In the patients the duration of diabetes was at least 10 years. Diabetic nephropathy was defined as urinary albumin excretion of > or = 30 mg/24 h. The HpaII polymorphism in intron 2 of the ANP gene was determined using PCR amplification followed by restriction digest. Alleles were separated on agarose gels stained with ethidium bromide. We compared genotype distribution and allele frequencies between patients with and without nephropathy. No significant difference was observed either in type I (allele frequency without DN H1, 0.02/H2, 0.98 vs with DN H1, 0.05/H2, 0.95; P = 0.132) or in type II diabetes (allele frequency without DN H1, 0.04/H2, 0.96 vs with DN H1, 0.05/H2, 0.95; P = 0.551). The polymorphism in the gene for the atrial natriuretic peptide does not seem to play a major role in the development of diabetic nephropathy in either type I or in type II diabetes.