Recent studies have demonstrated that the FokI polymorphism may be associated with a wide variety of pathological and physiological phenotypes in different populations, such as variations in 1,25(OH)2D3 concentration47, variations in bone mineral density and fractures 48, alterations in insulin secretion and sensitivity to action49, metabolic syndrome50, and increased risk of some cancers51, depression, schizophrenia, bipolar disorder, and seasonal affective disorder. Here, INS is linked to major depressive disorder.