The involvement of leptin in the increased platelet activation in human obesity is not universally accepted, since recent studies provided conflicting results about platelet responsiveness to leptin in overweight and obesity [246, 247]; actually, in one study the effect of leptin on ADP-induced platelet aggregation is attenuated in obese individuals due to the receptor desensitization [245], whereas different results have been provided in another report [247]. This evidence concerns the gene LEP and obesity due to melanocortin 4 receptor deficiency.