A novel GATA2 distal enhancer mutation results in MonoMAC syndrome in 2 second cousins.

Mutations in the transcription factor GATA2 can cause MonoMAC syndrome, a GATA2 deficiency disease characterized by several findings, including disseminated nontuberculous mycobacterial infections, severe deficiencies of monocytes, natural killer cells, and B lymphocytes, and myelodysplastic syndrome. GATA2 mutations are found in âˆ¼90% of patients with a GATA2 deficiency phenotype and are largely missense mutations in the conserved second zinc-finger domain. Mutations in an intron 5 regulatory enhancer element are also well described in GATA2 deficiency. Here, we present a multigeneration kindred with the clinical features of GATA2 deficiency but lacking an apparent GATA2 mutation. Whole genome sequencing revealed a unique adenine-to-thymine variant in the GATA2 -110 enhancer 116,855 bp upstream of the GATA2 ATG start site. The mutation creates a new E-box consensus in position with an existing GATA-box to generate a new hematopoietic regulatory composite element. The mutation segregates with the disease in several generations of the family. Cell type-specific allelic imbalance of GATA2 expression was observed in the bone marrow of a patient with higher expression from the mutant-linked allele. Allele-specific overexpression of GATA2 was observed in CRISPR/Cas9-modified HL-60 cells and in luciferase assays with the enhancer mutation. This study demonstrates overexpression of GATA2 resulting from a single nucleotide change in an upstream enhancer element in patients with MonoMAC syndrome. Patients in this study were enrolled in the National Institute of Allergy and Infectious Diseases clinical trial and the National Cancer Institute clinical trial (both trials were registered at www.clinicaltrials.gov as #NCT01905826 and #NCT01861106, respectively).

Donor source and post-transplantation cyclophosphamide influence outcome in allogeneic stem cell transplantation for GATA2 deficiency.

GATA2 deficiency was described in 2011, and shortly thereafter allogeneic hematopoietic stem cell transplantation (HSCT) was shown to reverse the hematologic disease phenotype. However, there remain major unanswered questions regarding the type of conditioning regimen, type of donors, and graft-versus-host disease (GVHD) prophylaxis. We report 59 patients with GATA2 mutations undergoing HSCT at National Institutes of Health between 2013 and 2020. Primary endpoints were engraftment, reverse of the clinical phenotype, secondary endpoints were overall survival (OS), event-free survival (EFS), and the incidence of acute and chronic GVHD. The OS and EFS at 4 years were 85·1% and 82·1% respectively. Ninety-six percent of surviving patients had reversal of the hematologic disease phenotype by one-year post-transplant. Incidence of grade III-IV aGVHD in matched related donor (MRD) and matched unrelated donor recipients (URD) patients receiving Tacrolimus/Methotrexate for GVHD prophylaxis was 32%. In contrast, in the MRD and URD who received post-transplant cyclophosphamide (PT/Cy), no patient developed grade III-IV aGVHD. Six percent of haploidentical related donor (HRD) recipients developed grade III-IV aGVHD. In summary, a busulfan-based HSCT regimen in GATA2 deficiency reverses the hematologic disease phenotype, and the use of PT/Cy reduced the risk of both aGVHD and cGVHD.

ASXL1 and STAG2 are common mutations in GATA2 deficiency patients with bone marrow disease and myelodysplastic syndrome.

Patients with GATA2 deficiencyharbor de novo or inherited germline mutations in the GATA2 transcription factor gene, predisposing them to myeloid malignancies. There is considerable variation in disease progression, even among family members with the same mutation in GATA2. We investigated somatic mutations in 106 patients with GATA2 deficiency to identify acquired mutations that are associated with myeloid malignancies. Myelodysplastic syndrome (MDS) was the most common diagnosis (∼44%), followed by GATA2 bone marrow immunodeficiency disorder (G2BMID; ∼37%). Thirteen percent of the cohort had GATA2 mutations but displayed no disease manifestations. There were no correlations between age or sex with disease progression or survival. Cytogenetic analyses showed a high incidence of abnormalities (∼43%), notably trisomy 8 (∼23%) and monosomy 7 (∼12%), but the changes did not correlate with lower survival. Somatic mutations in ASXL1 and STAG2 were detected in ∼25% of patients, although the mutations were rarely concomitant. Mutations in DNMT3A were found in ∼10% of patients. These somatic mutations were found similarly in G2BMID and MDS, suggesting clonal hematopoiesis in early stages of disease, before the onset of MDS. ASXL1 mutations conferred a lower survival probability and were more prevalent in female patients. STAG2 mutations also conferred a lower survival probability, but did not show a statistically significant sex bias. There was a conspicuous absence of many commonly mutated genes associated with myeloid malignancies, including TET2, IDH1/2, and the splicing factor genes. Notably, somatic mutations in chromatin-related genes and cohesin genes characterized disease progression in GATA2 deficiency.

Venetoclax/decitabine for a pediatric patient with chronic myelomonocytic leukemia.

Chronic myelomonocytic leukemia (CMML) is a myelodysplastic syndrome (MDS)/myeloproliferative disorder most commonly seen in the elderly. We describe an adolescent with monosomy 7 CMML presenting as central diabetes insipidus (DI), who was treated with venetoclax and decitabine as a bridge to hematopoietic stem cell transplantation (HSCT). Central DI is a rare manifestation of monosomy 7-associated MDS including CMML, itself a rare manifestation of GATA2 deficiency, particularly in children. Venetoclax/decitabine was effective for treatment of CMML as a bridge to HSCT.

Rapid progression to AML in a patient with germline GATA2 mutation and acquired NRAS Q61K mutation.

GATA2 deficiency syndrome is caused by autosomal dominant, heterozygous germline mutations with widespread effects on immune, pulmonary and vascular systems. Patients commonly develop hematological abnormalities including bone marrow failure, myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). We present a patient with GATA2 mutation and MDS who progressed to AML over four months. Whole exome and targeted deep sequencing identified a new p.Q61K NRAS mutation in the bone marrow at the time of AML development. Rapid development of AML is possible in the setting of germline GATA2 mutation despite stable MDS, supporting close monitoring and consideration of early allogeneic transplantation.

MDS-associated mutations in germline GATA2 mutated patients with hematologic manifestations.

Germline mutation in GATA2 can lead to GATA2 deficiency characterized by a complex multi-system disorder that can present with many manifestations including variable cytopenias, bone marrow failure, myelodysplastic syndrome/acute myeloid leukemia (MDS/AML), and severe immunodeficiency. Penetrance and expressivity within families is often variable. There is a spectrum of bone marrow disease in symptomatic cytopenic patients ranging from hypocellular marrows without overt dysplasia to those with definitive MDS, AML, or chronic myelomonocytic leukemia. Relatives of probands with the same mutations may demonstrate minimal disease manifestations and normal marrows. A comprehensive clinical, hematological and genetic assessment of 25 patients with germline GATA2 mutation was performed. MDS-associated mutations were identified in symptomatic GATA2 patients both with overt MDS and in those with hypocellular/aplastic bone marrows without definitive dysplasia. Healthy relatives of probands harboring the same germline GATA2 mutations had essentially normal marrows that were overall devoid of MDS-associated mutations. The findings suggest that abnormal clonal hematopoiesis is a common event in symptomatic germline mutated GATA2 patients with MDS and also in those with hypocellular marrows without overt morphologic evidence of dysplasia, possibly indicating a pre-MDS stage warranting close monitoring for disease progression.

Expression of KRASG12V in Zebrafish Gills Induces Hyperplasia and CXCL8-Associated Inflammation.

The zebrafish (Danio rerio) represents an important animal model for analyzing genetic contributors to carcinogenesis. To assess the role for mutationally activated Ras in ovarian cancer, we developed a transgenic zebrafish model using the putative promoter for zebrafish insulin-like growth factor 3 (igf3) to drive expression of the human oncogene KRAS(G12V) fused to EGFP. A member of the IGF family, igf3 is unique to teleosts and reportedly exhibits gonad-specific expression in fish species. In contrast to previous studies, we observed igf3 expression in wild-type zebrafish gills in addition to gonads, indicating that igf3 expression is not necessarily gonad specific. In transgenic zebrafish, expression of EGFP-KRAS(G12V) driven by the igf3 promoter occurred only in the gills and resulted in proliferation of a putative progenitor cell population, chondroid hyperplasia, and localized inflammation. KRAS(G12V)-transformed cells in transgenic zebrafish showed activation of the ERK-MAP kinase pathway and expressed the zebrafish homologue for human CXCL8, a cytokine produced by mammalian Ras-transformed cells in tumor-associated inflammatory lesions. These findings indicate that KRAS(G12V)-transformed cells in zebrafish recruit inflammatory cells, but may require additional mutational events for neoplastic transformation. The conserved role for mutationally activated KRAS in leukocyte recruitment indicates that zebrafish can provide a valuable comparative model for Ras-associated inflammation.

BRCA2 and TP53 collaborate in tumorigenesis in zebrafish.

Germline mutations in the tumor suppressor genes BRCA2 and TP53 significantly influence human cancer risk, and cancers from humans who inherit one mutant allele for BRCA2 or TP53 often display loss of the wildtype allele. In addition, BRCA2-associated cancers often exhibit mutations in TP53. To determine the relationship between germline heterozygous mutation (haploinsufficiency) and somatic loss of heterozygosity (LOH) for BRCA2 and TP53 in carcinogenesis, we analyzed zebrafish with heritable mutations in these two genes. Tumor-bearing zebrafish were examined by histology, and normal and neoplastic tissues were collected by laser-capture microdissection for LOH analyses. Zebrafish on a heterozygous tp53(M214K) background had a high incidence of malignant tumors. The brca2(Q658X) mutation status determined both the incidence of LOH and the malignant tumor phenotype. LOH for tp53 occurred in the majority of malignant tumors from brca2 wildtype and heterozygous mutant zebrafish, and most of these were malignant peripheral nerve sheath tumors. Malignant tumors in zebrafish with heterozygous mutations in both brca2 and tp53 frequently displayed LOH for both genes. In contrast, LOH for tp53 was uncommon in malignant tumors from brca2 homozygotes, and these tumors were primarily undifferentiated sarcomas. Thus, carcinogenesis in zebrafish with combined mutations in tp53 and brca2 typically requires biallelic mutation or loss of at least one of these genes, and the specific combination of inherited mutations influences the development of LOH and the tumor phenotype. These results provide insight into cancer development associated with heritable BRCA2 and TP53 mutations.

Acquired ASXL1 mutations are common in patients with inherited GATA2 mutations and correlate with myeloid transformation.

Inherited or sporadic heterozygous mutations in the transcription factor GATA2 lead to a clinical syndrome characterized by non-tuberculous mycobacterial and other opportunistic infections, a severe deficiency in monocytes, B cells and natural killer cells, and progression from a hypocellular myelodysplastic syndrome to myeloid leukemias. To identify acquired somatic mutations associated with myeloid transformation in patients with GATA2 mutations, we sequenced the region of the ASXL1 gene previously associated with transformation from myelodysplasia to myeloid leukemia. Somatic, heterozygous ASXL1 mutations were identified in 14/48 (29%) of patients with GATA2 deficiency, including four out of five patients who developed a proliferative chronic myelomonocytic leukemia. Although patients with GATA2 mutations had a similarly high incidence of myeloid transformation when compared to previously described patients with ASXL1 mutations, GATA2 deficiency patients with acquired ASXL1 mutation were considerably younger, almost exclusively female, and had a high incidence of transformation to a proliferative chronic myelomonocytic leukemia. These patients may benefit from allogeneic hematopoietic stem cell transplantation before the development of acute myeloid leukemia or chronic myelomonocytic leukemia. (ClinicalTrials.gov identifier NCT00018044, NCT00404560, NCT00001467, NCT00923364.).

Long-term follow-up of foamy viral vector-mediated gene therapy for canine leukocyte adhesion deficiency.

The development of leukemia following gammaretroviral vector-mediated gene therapy for X-linked severe combined immunodeficiency disease and chronic granulomatous disease (CGD) has emphasized the need for long-term follow-up in animals treated with hematopoietic stem cell gene therapy. In this study, we report the long-term follow-up (4-7 years) of four dogs with canine leukocyte adhesion deficiency (CLAD) treated with foamy viral (FV) vector-mediated gene therapy. All four CLAD dogs previously received nonmyeloablative conditioning with 200 cGy total body irradiation followed by infusion of autologous, CD34(+) hematopoietic stem cells transduced by a FV vector expressing canine CD18 from an internal Murine Stem Cell Virus (MSCV) promoter. CD18(+) leukocyte levels were >2% following infusion of vector-transduced cells leading to ongoing reversal of the CLAD phenotype for >4 years. There was no clinical development of lymphoid or myeloid leukemia in any of the four dogs and integration site analysis did not reveal insertional oncogenesis. These results showing disease correction/amelioration of disease in CLAD without significant adverse events provide support for the use of a FV vector to treat children with leukocyte adhesion deficiency type 1 (LAD-1) in a human gene therapy clinical trial.

Rehabilitation after myocardial infarction trial (RAMIT): multi-centre randomised controlled trial of comprehensive cardiac rehabilitation in patients following acute myocardial infarction.

BACKGROUND: It is widely believed that cardiac rehabilitation following acute myocardial infarction (MI) reduces mortality by approximately 20%. This belief is based on systematic reviews and meta-analyses of mostly small trials undertaken many years ago. Clinical management has been transformed in the past 30-40 years and the findings of historical trials may have little relevance now. OBJECTIVES: The principal objective was to determine the effect of cardiac rehabilitation, as currently provided, on mortality, morbidity and health-related quality of life in patients following MI. The secondary objectives included seeking programmes that may be more effective and characteristics of patients who may benefit more. DESIGN, SETTING, PATIENTS, OUTCOME MEASURES: A multi-centre randomised controlled trial in representative hospitals in England and Wales compared 1813 patients referred to comprehensive cardiac rehabilitation programmes or discharged to 'usual care' (without referral to rehabilitation). The primary outcome measure was all-cause mortality at 2 years. The secondary measures were morbidity, health service use, health-related quality of life, psychological general well-being and lifestyle cardiovascular risk factors at 1 year. Patient entry ran from 1997 to 2000, follow-up of secondary outcomes to 2001 and of vital status to 2006. A parallel study compared 331 patients in matched 'elective' rehabilitation and 'elective' usual care (without rehabilitation) hospitals. RESULTS: There were no significant differences between patients referred to rehabilitation and controls in mortality at 2 years (RR 0.98, 95% CI 0.74 to 1.30) or after 7-9 years (0.99, 95% CI 0.85 to 1.15), cardiac events, seven of eight domains of the health-related quality of life scale ('Short Form 36', SF36) or the psychological general well-being scale. Rehabilitation patients reported slightly less physical activity. No differences between groups were reported in perceived overall quality of cardiac aftercare. Data from the 'elective' hospitals comparison concurred with these findings. CONCLUSION: In this trial, comprehensive rehabilitation following MI had no important effect on mortality, cardiac or psychological morbidity, risk factors, health-related quality of life or activity. This finding is consistent with systematic reviews of all trials reported since 1983. The value of cardiac rehabilitation as practised in the UK is open to question.

brca2 in zebrafish ovarian development, spermatogenesis, and tumorigenesis.

Humans with inherited mutations in BRCA2 are at increased risk for developing breast and ovarian cancer; however, the relationship between BRCA2 mutation and these cancers is not understood. Studies of Brca2 mutation by gene targeting in mice are limited, given that homozygous Brca2 mutation typically leads to early embryonic lethality. We established a zebrafish line with a nonsense mutation in brca2 exon 11 (brca2(Q658X)), a mutation similar in location and type to BRCA2 mutations found in humans with hereditary breast and ovarian cancer. brca2(Q658X) homozygous zebrafish are viable and survive to adulthood; however, juvenile homozygotes fail to develop ovaries during sexual differentiation. Instead, brca2(Q658X) homozygotes develop as infertile males with meiotic arrest in spermatocytes. Germ cell migration to the embryonic gonadal ridge is unimpaired in brca2(Q658X) homozygotes; thus, failure of ovarian development is not due to defects in early establishment of the embryonic gonad. Homozygous tp53 mutation rescues ovarian development in brca2(Q658X) homozygous zebrafish, reflecting the importance of germ cell apoptosis in gonad morphogenesis. Adult brca2(Q658X) homozygous zebrafish are predisposed to testicular neoplasias. In addition, tumorigenesis in multiple tissues is significantly accelerated in combination with homozygous tp53 mutation in both brca2(Q658X) homozygous and brca2(Q658X) heterozygous zebrafish. These studies reveal critical roles for brca2 in ovarian development and tumorigenesis in reproductive tissues.

A WHIM-sical zebrafish.

In this issue of Blood, Walters and colleagues describe an elegant model of WHIM syndrome in the zebrafish embryo. By allowing the movement of WHIM neutrophils to be observed in live animals, this model dramatically illustrates the dynamics of the interaction between the neutrophil chemokine receptor CXCR4 and its receptor ligand (stromal-derived factor-1 [SDF-1], also known as CXCL12) in th hallmark of WHIM-excessive neutrophil adhesion to the marrow stroma.

Kinesin-8 from fission yeast: a heterodimeric, plus-end-directed motor that can couple microtubule depolymerization to cargo movement.

Fission yeast expresses two kinesin-8s, previously identified and characterized as products of the klp5(+) and klp6(+) genes. These polypeptides colocalize throughout the vegetative cell cycle as they bind cytoplasmic microtubules during interphase, spindle microtubules, and/or kinetochores during early mitosis, and the interpolar spindle as it elongates in anaphase B. Here, we describe in vitro properties of these motor proteins and some truncated versions expressed in either bacteria or Sf9 cells. The motor-plus-neck domain of Klp6p formed soluble dimers that cross-linked microtubules and showed both microtubule-activated ATPase and plus-end-directed motor activities. Full-length Klp5p and Klp6p, coexpressed in Sf9 cells, formed soluble heterodimers with the same activities. The latter recombinant protein could also couple microbeads to the ends of shortening microtubules and use energy from tubulin depolymerization to pull a load in the minus end direction. These results, together with the spindle localizations of these proteins in vivo and their requirement for cell viability in the absence of the Dam1/DASH kinetochore complex, support the hypothesis that fission yeast kinesin-8 contributes both to chromosome congression to the metaphase plate and to the coupling of spindle microtubules to kinetochores during anaphase A.

Novel interactions of fission yeast kinesin 8 revealed through in vivo expression of truncation alleles.

Fission yeast expresses two kinesin 8s, klp5+ and klp6+, which are important for diverse cellular functions: mitosis, meiosis, and the maintenance of normal cell morphology. During vegetative growth these motors display complex localization patterns, moving from the cytoplasm during interphase to the kinetochores in early mitosis, the interpolar spindle in anaphase B, and then back into the cytoplasm. We have expressed GFP-tagged alleles of domains from these motors, seeking the signals required for their localizations. The tail of Klp5p localized to the interphase nucleus, more specifically to telomeres. Addition of the neck re-directed this fragment to microtubules in the cytoplasm. Klp6-tail and the neck-tail domains of both motors localized at microtubule ends. Klp6-neck-tail localized to the spindle in early mitosis but to the pole-proximal ends of the spindle in anaphase B. The Klp5-motor and motor-neck localized to microtubules, often causing them to bundle. Over-expression of Klp6-motor or motor-neck resulted in shorter microtubules. These localization patterns were no different when constructs were expressed in strains lacking either or both of the endogenous, full-length proteins. Our results indicate that the localization signals for these kinesins are not derived from simple amino acid sequences but from complex interactions among multiple domains of each motor.

Arrhythmogenic mutation-linked defects in ryanodine receptor autoregulation reveal a novel mechanism of Ca2+ release channel dysfunction.

Arrhythmogenic cardiac ryanodine receptor (RyR2) mutations are associated with stress-induced malignant tachycardia, frequently leading to sudden cardiac death (SCD). The causative mechanisms of RyR2 Ca2+ release dysregulation are complex and remain controversial. We investigated the functional impact of clinically-severe RyR2 mutations occurring in the central domain, and the C-terminal I domain, a key locus of RyR2 autoregulation, on interdomain interactions and Ca2+ release in living cells. Using high-resolution confocal microscopy and fluorescence resonance energy transfer (FRET) analysis of interaction between fusion proteins corresponding to amino- (N-) and carboxyl- (C-) terminal RyR2 domains, we determined that in resting cells, RyR2 interdomain interaction remained unaltered after introduction of SCD-linked mutations and normal Ca2+ regulation was maintained. In contrast, after channel activation, the abnormal Ca2+ release via mutant RyR2 was intrinsically linked to altered interdomain interaction that was equivalent with all mutations and exhibited threshold characteristics (caffeine >2.5 mmol/L; Ca2+ >150 nmol/L). Noise analysis revealed that I domain mutations introduced a distinct pattern of conformational instability in Ca2+ handling and interdomain interaction after channel activation that was absent in signals obtained from the central domain mutation. I domain-linked channel instability also occurred in intact RyR2 expressed in CHO cells and in HL-1 cardiomyocytes. These new insights highlight a critical role for mutation-linked defects in channel autoregulation, and may contribute to a molecular explanation for the augmented Ca2+ release following RyR2 channel activation. Our findings also suggest that the mutational locus may be an important mechanistic determinant of Ca2+ release channel dysfunction in arrhythmia and SCD.

Low utilization and wide interhospital variation in investigation of patients after acute myocardial infarction: inadequate resources or insufficient evidence?

BACKGROUND: Guidelines for the management of patients with acute myocardial infarction are available, but implementation may be difficult when resources are limited. OBJECTIVE: The aim of this study was to investigate whether resources, manpower or access to specialist facilities affect care following myocardial infarction. PATIENTS AND METHODS: A representative sample of 1595 patients in all 19 district general hospitals in Wales was analysed for differences in use of investigations and prescription of secondary prevention and how these factors were related to provision of cardiologists and coronary care beds and distance from specialist cardiac services. RESULTS: Inpatient investigation rates were low and there were wide interhospital variations for exercise testing [mean 42%; interquartile range (IQR) 27-59%] and echocardiography (mean 46%; IQR 33-66%). In comparison, prescription of secondary prevention was similar to European standards and showed less interhospital variation (beta blockers mean 48%; IQR 44-54%; angiotensin-converting enzyme inhibitors mean 59%; IQR 43-63%). There was little association between investigation or secondary prevention rates and cardiac services, but overall rates and provision were low. CONCLUSION: Delivery of care after acute myocardial infarction for stratifying risk and preventing recurrence was unrelated to relative provision or distance from specialist centres. Low use of investigations and high interhospital variability could imply limited access to resources such as echocardiography. Higher rates of prescription of drugs, with less variation between hospitals, argues against low utilization because of insufficient evidence.