No effect of a Taql polymorphism in DNA at the endothelin I (EDN1) locus on normal blood pressure level or variability

Endothelin is a peptide reported to be one of the most potent vasoconstrictors known. Presumably, endothelin could play a role in the physiological regulation of blood pressure in healthy or hypertensive people. We have studied a normal restriction fragment length polymorphism (RFLP) at the endothelin-I (EDN1) locus detected with the restriction enzyme TaqI. In three different series comprising 166, 120 and 207 unrelated individuals, we found no evidence for association between genotype in this polymorphism and level of systolic or diastolic blood pressure. In two series of 156 and 117 monozygotic (MZ) twin pairs, respectively, there was no difference between genotypes in within-pair variation in systolic or diastolic blood pressure. Thus neither "level gene" nor "variability gene" effects of normal genes at the EDN1 locus could be detected with the polymorphism analyzed, in healthy population samples.