CD24 and obesity due to melanocortin 4 receptor deficiency: This hypothesis is confirmed by direct and sialylation-dependent CD24-Siglec E interaction, requirement of CD24 in either the same (cis) or separate cells (trans) in constitutional activation of Siglec E. More importantly, in a Siglec E-dependent manner, CD24Fc effectively suppressed obesity, dyslipidemia, insulin resistance, and NASH in multiple mouse models.