PRPS1 and severe combined immunodeficiency: Our work may also help explain observations regarding genetic disorders of the immune compartment such as severe combined immunodeficiency (SCID)53, Arts syndrome54, Charcot-Marie-Tooth disease-5 (CMTX5)55, DFN242 and lupus erythematosus56 some of which are X-linked disorders arising from mutations in PRPS1 or PRPS2.