SAA1 and obesity due to melanocortin 4 receptor deficiency: Although SAA concentration during APR can reach concentrations as high as 1 mg/mL, we show here that at much lower concentrations (1 to 30 μg/mL), similar to those observed in obese patients [17], SAA has already clear-cut effects on adipocytes and could also contribute to the metabolic and endocrine characteristics of obesity.