APLN and acanthosis nigricans: When APLN T-1860C and APLNR G212A were used as a dependent variable, the results showed no significant associations of these two polymorphisms with apelin concentration and anthropometric-cardiometabolic parameters (P > 0.05) after adjusting for potential covariates including age, sex and acanthosis nigricans (see Supplementary file; Table S2).