MPO and Chediak-Higashi syndrome: Among common DEPs shared in this pathway, levels of p22-phox (CYBA), cathepsin G (CTSG), and myeloperoxidase (MPO), were reduced in samples from patients with HPS type 2, whereas those of cathepsin G and ELANE (ELANE) were reduced in patients with CHS relative to controls (Fig. 4F and Fig. 5C).