PDX models retain NB-specific molecular features, including cellular differentiation status, protein marker expression (synaptophysin, chromogranin A, NCAM/CD56), chromosomal copy number changes (including 1p loss, MYCN amplification, 17q gain), mutational profiles, and DNA methylation status (32, 34, 37–41). The gene discussed is MYCN; the disease is neuroblastoma.