GYPA and hypothyroidism: Because of TRs’ role in erythropoiesis, in patients, hypothyroidism is frequently associated with mild anemia [31,32,33] and erythroid cultures from hypothyroid patient cells show delayed differentiation of progenitors, high levels of c-kit (expressed on the surface of immature cells) and reduced GpA (glycophorin A, expressed by more mature erythroid cells) [34].