SLC22A3 and hyperkeratosis lenticularis perstans: Thus, this study aims to (i) explore the connection of the SYTL3 (rs9364496, rs6455600, rs2129209, and rs9456350) and SLC22A3 (rs446809 and rs539298) SNPs and serum lipid profiles between the Maonan and Han ethnicities; (ii) assess the correlation of their haplotypes with HLP morbidity between both ethnic groups; (iii) detect the potential gene–gene (G × G) and gene–environment (G × E) interactions that may impact the clinical HLP manifestations in the two ethnic groups.