While no direct data are available for HFDM, recent data have shown that plasma renin activity was higher and negatively correlated to muscle mass (i.e. appendicular skeletal muscle mass index) in patients with HFDM but not HF, suggesting a role for the renin–angiotensin system56 that could act downstream via ROS‐dependent signalling to induce wasting (Figure2). The gene discussed is REN; the disease is hydrops fetalis.