LAUSR

Monosomy 7 (−7) occurs in various types of paediatric myeloid disorders and has a poor prognosis. Recent studies have demonstrated that patients with germline gain‐of‐function SAMD9/9L variants and loss‐of‐function GATA2 variants are prone to developing myelodysplastic syndrome (MDS) associated with −7. However, the prevalence of the genetic variants among paediatric haematologic disorders with −7 is unknown. The present study screened germline variants of GATA2 and SAMD9/9L in 25 patients with various types of paediatric haematological disorders associated with −7. The diagnoses of the 25 patients included MDS (n = 10), acute myeloid leukaemia (AML) and myeloid sarcomas (n = 9), juvenile myelomonocytic leukaemia (n = 3) and other disorders (n = 3). Seven patients with a germline pathogenic GATA2 variant were found. For SAMD9/9L screening, next‐generation sequencing was used to detect low‐abundance variants and found four novel germline variants. Functional analysis revealed that three out of the four variants showed growth‐restricting capacity in vitro and thus, were judged to be pathogenic. Cases with GATA2 mutation tended to be older, compared to those with SAMD9/9L mutations. In conclusion, GATA2 and SAMD9/9L were sequenced in 25 patients with paediatric haematologic disorders associated with −7, and 40% of them were found to have some pathogenic germline variants in the three genes.