Influence of genetic variants in FADS2 and ELOVL2 genes on BMI and PUFAs homeostasis in children and adolescents with obesity

Background: Several studies identified genetic variants in FADS and ELOVL2 genes associated with obesity-related conditions, such as alterations in blood lipid parameters and insulin homeostasis. The aim of this cross-sectional study was to determine whether FADS and ELOVL2 genetic variants were associated with obesity and adiposity, besides dyslipidaemia and insulin resistance, in a large sample of obese children and adolescents. Materials and methods: One thousand six hundred and forty-nine obese children underwent physical examination, anthropometry, fasting blood tests measuring plasma glucose, lipid and liver profile. Two genetic variants were genotyped: rs2236212 in ELOVL2 gene and rs1535 in FADS2, for the gene cluster FADS. In a subgroup of obese children (n = 105), erythrocyte fatty acid composition was measured. Generalized linear models were used to assess association between genotypes and variables. Results: A positive association between zBMI and the minor allele of rs2236212 (p = 0.028), the major allele of rs1535 (p = 0.046) and the genetic score (p = 0.008), created by summing up both risk alleles, were found. The estimation of enzymatic activity revealed that minor alleles were associated significantly with a reduction of the enzymatic activity of elongase and desaturase (p = 0.048 and p = 0.0001, respectively). Discussion and conclusions: Common variants in the FADS2 and ELOVL2 genes were associated with BMI in a large population of obese Italian children. These SNPs were associated with alterations in LC-PUFAs homeostasis, not accompanied by modifications of plasma lipids or HOMA-IR. These findings provide additional support to the genetics accounting for BMI interindividual variability and the molecular basis of obesity