Anti-PF4/P antibodies have not been described in association with anemia, but we observed an inverse correlation in patients with UM between anti-PF4/P and HgB (Rs = –0.225, P = 0.015) and packed cell volume (PCV) (Rs = –0.200, P = 0.029) (Supplemental Table 1). This evidence concerns the gene PF4 and anemia (phenotype).