The sensitivity of serum NRG1 as a predictor for different levels of depression pre- and post-LSG has been estimated to be 92.45% and 52.94% respectively while its is 69.09% and 79.73% respectively at cut-off values of ≤3.5 and ≤2.5 ng/ml. This evidence concerns the gene NRG1 and major depressive disorder.