Successful correction of anaemia in patients with nephrotic syndrome depends on the underlying cause, which may be one of or a combination of the following: urinary losses of erythropoietin (EPO), iron, transcobalamin and transferrin (transferrin saturation and ferritin level are unreliable in CNS); vitamin B12 and/or copper deficiency; and ACE inhibitor toxicity87. The gene discussed is EPO; the disease is nephrotic syndrome.