In another unreported example highlighting the diversity of MC mediators and their effects, author LBA identified an MCAS patient also suffering both sickle cell anemia and dialysis-dependent end-stage kidney disease resulting in unusually severe anemia occasioning transfusion dependence despite high-intensity erythropoietin treatment—and in whom treatment with montelukast for chronic mild asthma quickly resolved the excess anemia and the transfusion dependence. This evidence concerns the gene EPO and anemia (phenotype).