RPA3, although less than half the size of RPA2 (121 amino acids, 14kDa) had 8 unique germline heterozygous variants (n = 4 ultra-rare, n = 3 novel) in 10 cases of pediatric cancers, including 6 hematologic (B-ALL n = 3, T-ALL n = 1, AML n = 1, Hodgkin’s lymphoma n = 1), 3 solid tumors (Wilms tumor n = 2, sarcoma n = 1) and 1 CNS (medulloblastoma) cancers (Figure 1E; Tables 1–3). The gene discussed is RPA3; the disease is medulloblastoma.