Haploinsufficiency of the hematopoietic transcription factor GATA2 underlies monocytopenia and mycobacterial infections; dendritic cell, monocyte, B, and natural killer (NK) lymphoid deficiency; familial myelodysplastic syndromes (MDS)/acute myeloid leukemia (AML); and Emberger syndrome (primary lymphedema with MDS). A comprehensive examination of the clinical features of GATA2 deficiency is currently lacking. We reviewed the medical records of 57 patients with GATA2 deficiency evaluated at the National Institutes of Health from January 1, 1992, to March 1, 2013, and categorized mutations as missense, null, or regulatory to identify genotype-phenotype associations. We identified a broad spectrum of disease: hematologic (MDS 84%, AML 14%, chronic myelomonocytic leukemia 8%), infectious (severe viral 70%, disseminated mycobacterial 53%, and invasive fungal infections 16%), pulmonary (diffusion 79% and ventilatory defects 63%, pulmonary alveolar proteinosis 18%, pulmonary arterial hypertension 9%), dermatologic (warts 53%, panniculitis 30%), neoplastic (human papillomavirus+ tumors 35%, Epstein-Barr virus+ tumors 4%), vascular/lymphatic (venous thrombosis 25%, lymphedema 11%), sensorineural hearing loss 76%, miscarriage 33%, and hypothyroidism 14%. Viral infections and lymphedema were more common in individuals with null mutations (P = .038 and P = .006, respectively). Monocytopenia, B, NK, and CD4 lymphocytopenia correlated with the presence of disease (P < .001). GATA2 deficiency unites susceptibility to MDS/AML, immunodeficiency, pulmonary disease, and vascular/lymphatic dysfunction. Early genetic diagnosis is critical to direct clinical management, preventive care, and family screening.

• Germline gain-of-function mutations in STAT3 lead to lymphoproliferation and autoimmunity with prominent cytopenias.• Mutations in STAT3 cause altered regulatory T cells and cytokine signaling.Germline loss-of-function mutations in the transcription factor signal transducer and activator of transcription 3 (STAT3) cause immunodeficiency, whereas somatic gain-offunction mutations in STAT3 are associated with large granular lymphocytic leukemic, myelodysplastic syndrome, and aplastic anemia. Recently, germline mutations in STAT3 have also been associated with autoimmune disease. Here, we report on 13 individuals from 10 families with lymphoproliferation and early-onset solid-organ autoimmunity associated with 9 different germline heterozygous mutations in STAT3. Patients exhibited a variety of clinical features, with most having lymphadenopathy, autoimmune cytopenias, multiorgan autoimmunity (lung, gastrointestinal, hepatic, and/or endocrine dysfunction), infections, and short stature. Functional analyses demonstrate that these mutations confer a gain-of-function in STAT3 leading to secondary defects in STAT5 and STAT1 phosphorylation and the regulatory T-cell compartment. Treatment targeting a cytokine pathway that signals through STAT3 led to clinical improvement in 1 patient, suggesting a potential therapeutic option for such patients. These results suggest that there is a broad range of autoimmunity caused by germline STAT3 gain-of-function mutations, and that hematologic autoimmunity is a major component of this newly described disorder. Some patients for this study were enrolled in a trial registered at www.clinicaltrials.gov as #NCT00001350. (Blood. 2015;125(4):591-599)

Super-resolution imaging provides a new look at how the lytic granules in natural killer cells penetrate the filamentous actin network of the immunological synapse.

SUMMARY Besides circadian rhythms, oscillations cycling with a 12h period exist. However, the prevalence, origin, regulation and function of mammalian 12h rhythms remain elusive. Utilizing an unbiased mathematical approach identifying all superimposed oscillations, we uncovered prevalent 12h gene expression and metabolic rhythms in mouse liver, coupled with a physiological 12h unfolded protein response oscillation. The mammalian 12h rhythm is cell-autonomous, driven by a dedicated 12h pacemaker distinct from the circadian clock and can be entrained in vitro by metabolic and ER stress cues. Mechanistically, we identified XBP1s as a transcriptional regulator of the mammalian 12h-clock. Down-regulation of the 12h gene expression strongly correlates with human hepatic steatosis and steatohepatitis, implying its importance in maintaining metabolic homeostasis. The mammalian 12h rhythm of gene expression also is conserved in nematodes and crustaceans, indicating an ancient origin of the 12h-clock. Our work sheds new light on how perturbed biological rhythms contribute to human disease.

Background Primary immunodeficiency diseases (PIDDs) are clinically and genetically heterogeneous disorders thus far associated with mutations in more than 300 genes. The clinical phenotypes derived from distinct genotypes may overlap. Genetic etiology can be a prognostic indicator of disease severity and can influence treatment decisions. Objective To investigate the ability of whole-exome screening methods to detect disease-causing variants in individuals with PIDDs. Methods Individuals with PIDDs from 278 families from 22 countries were investigated using whole-exome sequencing (WES). Computational CNV prediction pipelines and an exome-tiling chromosomal microarray were also applied to identify intragenic copy number variants (CNVs). Analytic approaches initially focused on 475 known or candidate PIDD genes, but were non-exclusive and were further tailored based upon clinical data, family history and immunophenotyping. Results A likely molecular diagnosis was achieved in 110 (40%) unrelated probands. Clinical diagnosis was revised in about half (60/110) and management was directly altered in nearly a quarter (26/110) of families based on the molecular findings. Twelve PIDD-causing CNVs were detected, including seven smaller than 30 Kb that would not have been detected with conventional diagnostic CNV arrays. Conclusion This high-throughput genomic approach enabled detection of disease-related variants in unexpected genes, permitted detection of low-grade constitutional, somatic and revertant mosaicism, and provided evidence of a mutational burden in mixed PIDD immunophenotypes.

Key Points Mutations in GATA2 are a cause of human NK cell deficiency. GATA2 is required for human NK cell maturation, specifically maintenance of the CD56bright subset.

Natural killer (NK) cell-mediated cytotoxicity is governed by the formation of a lytic immune synapse in discrete regulated steps, which give rise to an extensive array of cellular checkpoints in accessing NK cell-mediated cytolytic defense. Appropriate progression through these cell biological steps is critical for the directed secretion of specialized secretory lysosomes and subsequent target cell death. Here we highlight recent discoveries in the formation of the NK cell cytolytic synapse as well as the molecular steps and cell biological checkpoints required for this essential host defense process.

SummaryNatural killer (NK) cells are innate immune effectors that lyse virally infected and tumorigenic cells through the formation of an immunological synapse. Actin remodeling at the lytic immunological synapse is a critical requirement for multiple facets of cytotoxic function. Activating receptor and integrin signaling leads to the regulated turnover and remodeling of actin, which is required for adhesion, sustained receptor signaling, and ultimately exocytosis. NK cells undergo lytic granule exocytosis in hypodense regions of a pervasive actin network. Although these requirements have been well demonstrated, neither the dynamic regulation of synaptic actin nor its specific function, however, has been determined at a nanoscale level. Here, live-cell super-resolution microscopy demonstrates nanoscale filamentous actin dynamism in NK cell lytic granule secretion. Following cell spreading, the overall content of the branched actin network at an immune synapse is stable over time and contains branched actin fibers and discrete actin foci. Similar actin architecture is generated in cytolytic T cells, although the timescale differs from that of NK cells. Individual filament displacement leads to stochastic clearance formation and disappearance, which are independent of lytic granule positioning. Actin dynamism is dependent upon branched network formation mediated by Arp2/3 and contractility generated by myosin IIA. Importantly, the use of small-molecule inhibitors demonstrates that actin dynamism is ultimately needed for granule secretion. Thus, we describe a requirement for nanoscale actin fiber rearrangement in generating the complex actin architecture that enables lytic granule secretion.