Interleukin-1 Alpha Polymorphisms Are Associated With Body Mass Index in Male But Not in Female Adolescents

The Interleukin (IL)-1 family of cytokines plays a key role in the inflammatory response. Genes coding for IL-1α, IL-1β, and IL-1Ra are located together as a block gene known as the IL-1 cluster. This genomic region shows wide nucleotide variability, and some polymorphisms have been widely studied and associated with features related to the metabolic syndrome.

Eight polymorphisms within three genes of the IL-1 cluster, including IL1A (rs3783553, rs17561, and rs1800587), IL1B (rs1143634, rs1143627, and rs16944) and IL1RN (rs419598 and rs2234663) were genotyped in 460 Mexican adolescents. Genotype and haplotype frequencies are reported, as well as the linkage disequilibrium analysis. Genetic associations with some anthropometric and metabolic traits were evaluated.

Allele frequencies were similar to those found in other populations, and genotype proportions were according to the Hardy-Weinberg equilibrium. Seven haplotypes were observed at frequencies ≥5%. Of the entire cluster, only the rs17561-rs1800587 and rs1143627-rs16944 pairs showed highest and significant linkage disequilibrium values. An haplotype of IL1A, rs17561T-rs1800587T, was significantly associated with increase in body mass index in males (p <0.008), whereas IL1B and IL1RN variants showed associations with insulin, and hs-CRP (p <0.05).

Some MetS parameters seem to be influenced by variations in the IL-1 gene cluster in Mexican adolescents. These variations may confer risk for metabolic alterations from early ages, and and these risks may be different when variables such as sex are considered. Strategies leading to generate protective behaviors could be designed to take into account specific variations in the IL-1 gene cluster and biological conditions such as sex.