DNA methylation levels in the CpG sites annotated to FADS2 and FADS1 were analyzed from liver samples of 95 obese participants of the Kuopio Obesity Surgery Study (34 men and 61 women, age 49.5 ± 7.7 years, BMI 43.0 ± 5.7 kg/m2) using the Infinium HumanMethylation450 BeadChip (Illumina). The gene discussed is FADS1; the disease is obesity due to melanocortin 4 receptor deficiency.