AGTR1 (angiotensin II receptor type 1), A1166C polymorphism

The AGTR1 A1166C genotype assay (also referred to as the AT1R A1166C SNP or 3′UTR variant) identifies the A/A, A/C, and C/C genotypes to appraise genetic predisposition to arterial hypertension. The C allele impairs microRNA‑155–mediated repression of AGTR1, which can increase receptor expression and has been reported at higher frequency in hypertensive groups than in normotensive controls. Results from AGTR1 A1166C testing provide adjunctive information for hypertension risk assessment and are interpreted in concert with clinical findings and other laboratory data.

Hypertension reflects the combined effects of genetic susceptibility and environmental influences, with the renin–angiotensin system (RAS) as a central pathway. Angiotensin II, generated from angiotensin I by angiotensin‑converting enzyme, produces vasoconstriction and stimulates aldosterone secretion predominantly through the angiotensin II type 1 receptor (AT1R) encoded by AGTR1. The A1166C substitution lies within the AGTR1 3′ untranslated region and modifies binding by microRNA miR‑155. miR‑155 downregulates expression from the A allele, whereas the C allele disrupts this interaction, leading to relatively higher receptor expression. This mechanistic effect is consistent with observations from multiple cohorts in which the C allele and A/C or C/C genotypes are associated with increased hypertension risk. The C‑allele frequency in European populations is approximately 27%. Individuals with the A/A genotype are generally not linked to increased risk, whereas A/C and C/C genotypes have shown higher risk in some studies. Interpretation should incorporate additional genetic data, clinical context, and routine laboratory results.