Background: TP53 mutations are associated with poor prognosis in myelodysplastic neoplasm (MDS) and AML. The updated 5th WHO classification and International Consensus Classification (ICC) categorize TP53-mutated MDS and AML as unique entities. We conducted a multicenter study in Korea to investigate the characteristics of TP53-mutated MDS and AML, focusing on diagnostic aspects based on updated classifications. Methods: This study included patients aged ≥ 18 yrs who were diagnosed as having MDS(N = 1,244) or AML (N = 2,115) at six institutions. The results of bone marrow examination, cytogenetic studies, and targeted next-generation sequencing, including TP53, were collected and analyzed. Results: TP53 mutations were detected in 9.3% and 9.2% of patients with MDS and AML, respectively. Missense mutation was the most common, with hotspot codons R248/ R273/G245/Y220/R175/C238 accounting for 25.4% of TP53 mutations. Ten percent of patients had multiple TP53 mutations, and 78.4% had a complex karyotype. The median variant allele frequency (VAF) of TP53 mutations was 41.5%, with a notable difference according to the presence of a complex karyotype. According to the 5th WHO classification and ICC, the multi-hit TP53 mutation criteria were met in 58.6% and 75% of MDS patients, respectively, and the primary determinants were a TP53 VAF > 50% for the 5th WHO classification and the presence of a complex karyotype for the ICC. Conclusions Collectively, we elucidated the molecular genetic characteristics of patients with TP53-mutated MDS and AML, highlighting key factors in applying TP53 mutation-related criteria in updated classifications, which will aid in establishing diagnostic strategies.

Non-Down syndrome pediatric acute megakaryoblastic leukemia (AMKL) may be classified according to the presence of recurrent genetic abnormalities with prognostic relevance. In this case study, we report on a girl with AMKL, 32 months old at the time of diagnosis, in whom we confirmed the presence of the cryptic, poor prognosis NUP98::KDM5A fusion. The patient achieved complete remission (CR) with the first course of chemotherapy, underwent haploidentical family donor hematopoietic stem cell transplantation (HSCT) without event, but relapsed 5 months after HSCT. Through this case report, we emphasize the good initial response to chemotherapy, and the early relapse despite undergoing HSCT in first CR. We review the limited literature on NUP98::KDM5A (+) pediatric AML, and underscore the need for further study to improve the outcome of patients with this rare AML subtype.

Non-Down syndrome pediatric acute megakaryoblastic leukemia (AMKL) may be classified according to the presence of recurrent genetic abnormalities with prognostic relevance. In this case study, we report on a girl with AMKL, 32 months old at the time of diagnosis, in whom we confirmed the presence of the cryptic, poor prognosis NUP98::KDM5A fusion. The patient achieved complete remission (CR) with the first course of chemotherapy, underwent haploidentical family donor hematopoietic stem cell transplantation (HSCT) without event, but relapsed 5 months after HSCT. Through this case report, we emphasize the good initial response to chemotherapy, and the early relapse despite undergoing HSCT in first CR. We review the limited literature on NUP98::KDM5A (+) pediatric AML, and underscore the need for further study to improve the outcome of patients with this rare AML subtype.

Non-Down syndrome pediatric acute megakaryoblastic leukemia (AMKL) may be classified according to the presence of recurrent genetic abnormalities with prognostic relevance. In this case study, we report on a girl with AMKL, 32 months old at the time of diagnosis, in whom we confirmed the presence of the cryptic, poor prognosis NUP98::KDM5A fusion. The patient achieved complete remission (CR) with the first course of chemotherapy, underwent haploidentical family donor hematopoietic stem cell transplantation (HSCT) without event, but relapsed 5 months after HSCT. Through this case report, we emphasize the good initial response to chemotherapy, and the early relapse despite undergoing HSCT in first CR. We review the limited literature on NUP98::KDM5A (+) pediatric AML, and underscore the need for further study to improve the outcome of patients with this rare AML subtype.

Non-Down syndrome pediatric acute megakaryoblastic leukemia (AMKL) may be classified according to the presence of recurrent genetic abnormalities with prognostic relevance. In this case study, we report on a girl with AMKL, 32 months old at the time of diagnosis, in whom we confirmed the presence of the cryptic, poor prognosis NUP98::KDM5A fusion. The patient achieved complete remission (CR) with the first course of chemotherapy, underwent haploidentical family donor hematopoietic stem cell transplantation (HSCT) without event, but relapsed 5 months after HSCT. Through this case report, we emphasize the good initial response to chemotherapy, and the early relapse despite undergoing HSCT in first CR. We review the limited literature on NUP98::KDM5A (+) pediatric AML, and underscore the need for further study to improve the outcome of patients with this rare AML subtype.

We report a patient diagnosed with a germ-cell tumor presenting with spinal muscular atrophy with lower limb predominance (SMA-LED) caused by a DYNC1H1 genetic variant. His clinical and electrophysiologic phenotype was compatible with SMA-LED. We identified a heterozygous missense variant (c.1793G>T) of DYNC1H1. This report expands the clinical spectrum of DYNC1H1-related disorders, and reinforces the importance of DYNC1H1 in both central and peripheral neuronal functions. We suggest that germ-cell tumors should be considered as a possible phenotype of DYNC1H1-related disorders.