Efforts to treat PD with replacement of prolidase activity included blood transfusions, gene therapy with an adenoviral vector and enzyme replacement with liposome-coated prolidase.3 5 All those approaches were of limited efficacy.3 Allogenic hematopoietic stem cell transplantation (HSCT) has been tried in a single patient, who despite reconstitution of prolidase activity died 3 months after HSCT of an invasive fungal infection.14 In this case, steroids, diverse csDMARDs and high-dose intravenous immunologlobulin treatment were unsuccessful in treating PD and associated immune dysregulation. Here, PEPD is linked to fungal infectious disease.