BDNF and congenital dyserythropoietic anemia: Low serpin E1/PAI-1 (P = 0.002), myeloperoxidase/MPO (P = 0.007), and BDNF (P = 0.016) but high IL-7 (P = 0.007) and ROBO4 (P = 0.006) levels were associated with severe CDA in FCCM patients, as determined by the Mann-Whitney U test (Fig. 4a–e).