Association of MFSD3 promoter methylation level and weight regain after gastric bypass: Assessment for 3 y after surgery

•Major facilitator superfamily domain 3 (MFSD3) has been recently associated with nutrient intake and adipose tissue homeostasis.•Weight regain after bariatric surgery was positively correlated with cg00010266 MFSD3 preoperative methylation levels. Genetic predisposition and epigenetic signatures could explain why some individuals regain the weight lost after different obesity treatments. Major facilitator superfamily domain 3 (MFSD3) is a family of membrane-bound solute carriers whose expression has been recently associated with nutrient intake and adipose tissue homeostasis. This study aimed to evaluate a possible association between MFSD3 preoperative methylation pattern and weight regain after bariatric surgery. This is a longitudinal study comprising 24 obese (body mass index > 35 m/kg2) women submitted to gastric bypass. Anthropometric measurements were evaluated at preoperative time and 1, 2, and 3 y after surgery, and then weight regain was calculated. Genomic DNA was extracted from leukocytes and was bisulfite modified by specific kits, according manufacturer's instructions. Methylation analysis was performed with the Infinium Human Methylation 450 K bead chip technology, and methylation level was expressed as a β value ranging from 0 (unmethylated) to 1 (fully methylated). Shapiro-Wilk, repeated-means analysis of variance, Spearman correlation, Mann-Whitney, and independent t tests were used in statistical analysis (P < 0.05). A total of 25% of patients regained significant weight. Weight regain after bariatric surgery was positively correlated with cg00010266 MFSD3 preoperative methylation levels (r = 0.6804, P = 0.0126). Moreover, cg00010266 MFSD3 baseline methylation levels were significantly higher in regainer patients than non-regainers (6.2 ± 1.5 versus 3.9 ± 1.2%, P = 0.026). Patients allocated in the higher cg00010266 MFSD3 preoperative methylation group had higher weight regain (4.1 ± 1.8 versus 6.7 ± 2.2 kg, P = 0.037). Preoperative hypermethylation of MFSD3 gene is significantly associated with weight regain and a worse response to gastric bypass.