Unexplained anaemia may be due to a blunted erythropoietic response in the context of iron inadequacy, higher circulating levels of proinflammatory cytokines (e.g. interleukin-6, which may reduce erythropoietin levels), diminished androgen levels, and reduced proliferative and regenerative capacity of bone marrow stem cells [44]. The gene discussed is EPO; the disease is anemia (phenotype).