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Key Points• Germline GATA2 mutations account for 15% of advanced and 7% of all primary pediatric MDS and do not influence overall survival. • The majority (72%) of adolescents with MDS and monosomy 7 carry an underlying GATA2 deficiency.Germline GATA2 mutations cause cellular deficiencies with high propensity for myeloid disease. We investigated 426 children and adolescents with primary myelodysplastic syndrome (MDS) and 82 cases with secondary MDS enrolled in 2 consecutive prospective studies of the European Working Group of MDS in Childhood (EWOG-MDS) conducted in Germany over a period of 15 years. Germline GATA2 mutations accounted for 15% of advanced and 7% of all primary MDS cases, but were absent in children with MDS secondary to therapy or acquired aplastic anemia. Mutation carriers were older at diagnosis and more likely to present with monosomy 7 and advanced disease compared with wild-type cases. For stratified analysis according to karyotype, 108 additional primary MDS patients registered with EWOG-MDS were studied. Overall, we identified 57 MDS patients with germline GATA2 mutations. GATA2 mutations were highly prevalent among patients with monosomy 7 (37%, all ages) reaching its peak in adolescence (72% of adolescents with monosomy 7). Unexpectedly, monocytosis was more frequent in GATA2-mutated patients. However, when adjusted for the selection bias from monosomy 7, mutational status had no effect on the hematologic phenotype. Finally, overall survival and outcome of hematopoietic stem cell transplantation (HSCT) were not influenced by mutational status. This study identifies GATA2 mutations as the most common germline defect predisposing to pediatric MDS with a very high prevalence in adolescents with monosomy 7. GATA2 mutations do not confer poor prognosis in childhood MDS. However, the high risk for progression to advanced disease must guide decision-making toward timely

Diagnosis, treatment, response monitoring, and outcome of pediatric acute myeloid leukemia (AML) have made enormous progress during the past decades. Because AML is a rare type of childhood cancer, with an incidence of approximately seven occurrences per 1 million children annually, national and international collaborative efforts have evolved. This overview describes these efforts and includes a summary of the history and contributions of each of the main collaborative pediatric AML groups worldwide. The focus is on translational and clinical research, which includes past, current, and future clinical trials. Separate sections concern acute promyelocytic leukemia, myeloid leukemia of Down syndrome, and relapsed AML. A plethora of novel antileukemic agents that have emerged, including new classes of drugs, are summarized as well. Finally, an important aspect of the treatment of pediatric AML--supportive care--and late effects are discussed. The future is bright, with a wide range of emerging innovative therapies and with more and more international collaboration that ultimately aim to cure all children with AML, with fewer adverse effects and without late effects.

Natural killer (NK) cells are circulating cytotoxic lymphocytes that exert potent and nonredundant antiviral activity and antitumoral activity in the mouse; however, their function in host defense in humans remains unclear. Here, we investigated 6 related patients with autosomal recessive growth retardation, adrenal insufficiency, and a selective NK cell deficiency characterized by a lack of the CD56 dim NK subset. Using linkage analysis and fine mapping, we identified the disease-causing gene, MCM4, which encodes a component of the MCM2-7 helicase complex required for DNA replication. A splice-site mutation in the patients produced a frameshift, but the mutation was hypomorphic due to the creation of two new translation initiation methionine codons downstream of the premature termination codon. The patients' fibroblasts exhibited genomic instability, which was rescued by expression of WT MCM4. These data indicate that the patients' growth retardation and adrenal insufficiency likely reflect the ubiquitous but heterogeneous impact of the MCM4 mutation in various tissues. In addition, the specific loss of the NK CD56 dim subset in patients was associated with a lower rate of NK CD56 bright cell proliferation, and the maturation of NK CD56 bright cells toward an NK CD56 dim phenotype was tightly dependent on MCM4-dependent cell division. Thus, partial MCM4 deficiency results in a genetic syndrome of growth retardation with adrenal insufficiency and selective NK deficiency.