CD55 and Protein-losing enteropathy: CD55 deficiency with hyper-activation of complement, angiopathic thrombosis, and protein-losing enteropathy (CHAPLE) disease is an ultra-rare, potentially fatal condition caused by mutations in the CD55 gene that prevent production of the CD55 protein that helps to regulate the complement system by accelerating the inactivation of the C3 and C5 convertases [1].