In the relapse biopsy samples from both patients, we identified new homozygous loss-of-function mutations in the kinases associated with the interferon-receptor pathway, with a Q503* nonsense mutation in the gene encoding Janus kinase 1 (JAK1) in Patient 1 (Fig. 2A and 2B) and a F547 splice-site mutation in the gene encoding Janus kinase 2 (JAK2) in Patient 2 (Fig. S4 in the Supplementary Appendix).