Moreover, we cannot readily explain the seemingly contradictory expression patterns in different cohorts reported here or in the literature, where PRRX1 and COL6A3 were downregulated in obesity as well as upregulated after fat loss in some cohorts, while being upregulated in insulin resistant relative to insulin sensitive subjects in others. This evidence concerns the gene COL6A3 and obesity due to melanocortin 4 receptor deficiency.