REN and obesity due to melanocortin 4 receptor deficiency: Besides glomerular hyperfiltration, which has been hypothesized as the main mechanism linking metabolically unhealthy obesity to renal injury [5], studies have shown that in the setting of obesity there is also an excess tubular sodium reabsorption [6], an overactivation of the renin-angiotensin-aldosterone system [7] and an increased activation of the renal sympathetic nervous system, which are also likely to play a role in the disease pathology.