Kim E. Nichols

Familial dyserythropoietic anaemia and thrombocytopenia due to an inherited mutation in GATA1.

Haematopoietic development is regulated by nuclear protein complexes that coordinate lineage-specific patterns of gene expression. Targeted mutagenesis in embryonic stem cells and mice has revealed roles for the X-linked gene Gata1 in erythrocyte and megakaryocyte differentiation. GATA-1 is the founding member of a family of DNA-binding proteins that recognize the motif WGATAR through a conserved multifunctional domain consisting of two C4-type zinc fingers. Here we describe a family with X-linked dyserythropoietic anaemia and thrombocytopenia due to a substitution of methionine for valine at amino acid 205 of GATA-1. This highly conserved valine is necessary for interaction of the amino-terminal zinc finger of GATA-1 with its essential cofactor, FOG-1 (for friend of GATA-1; refs). We show that the V205M mutation abrogates the interaction between Gata-1 and Fog-1, inhibiting the ability of Gata-1 to rescue erythroid differentiation in an erythroid cell line deficient for Gata-1 (G1E). Our findings underscore the importance of FOG-1:Gata-1 associations in both megakaryocyte and erythroid development, and suggest that other X-linked anaemias or thrombocytopenias may be caused by defects in GATA1.

Familial clustering of Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is considered a non‐hereditary disorder. Evaluation of the few familial cases might provide insight into its aetiology and pathogenesis. We conducted a survey to identify familial LCH cases. Data on family history, zygosity assessment in twins, clinical and laboratory features, treatment outcome, and present status were collected. According to variable confidence for twins monozygosity assessment, we termed these pairs ‘presumed monozygotic’ (pMZ). Nine families had more than one affected relative: five with LCH‐concordant twin pairs, four with LCH in siblings or cousins. Three twin pairs not concordant for LCH were also studied. Overall, four of five pMZ twin pairs and one of three dizygotic (DZ) pairs were concordant for LCH. The pMZ twins had simultaneous and early disease onset (mean age 5.4 months); onset was at 21 months in the DZ pair. Clinical features were similar in the pMZ pairs. One pair of DZ twins had disseminated LCH. The three healthy twins (one pMZ, two DZ) remain asymptomatic 0.3, 5.9 and 4.7 years, respectively, after disease onset in their co‐twins. Of the two families with affected non‐twin siblings, one had known parental consanguinity and the other possible consanguinity. Potential consanguinity was also present in one of the two families with affected first cousins. Our data support high LCH concordance rates in pMZ twins and add the finding of LCH concordance in one of three dizygotic pairs studied. Taken together with our identification of LCH in siblings and first cousins from known or possibly consanguineous families, and with prior reports of three affected parent–child pairs, the data support a role for genetic factor(s) in LCH. The work‐up of newly diagnosed patients should include a careful, extensive family history and chromosome studies. When possible, constitutional and/or lesional DNA should be obtained for future study.

2016 Classification Criteria for Macrophage Activation Syndrome Complicating Systemic Juvenile Idiopathic Arthritis

To develop criteria for the classification of macrophage activation syndrome (MAS) in patients with systemic juvenile idiopathic arthritis (JIA). A multistep process, based on a combination of expert consensus and analysis of real patient data, was conducted. A panel of 28 experts was first asked to classify 428 patient profiles as having or not having MAS, based on clinical and laboratory features at the time of disease onset. The 428 profiles comprised 161 patients with systemic JIA—associated MAS and 267 patients with a condition that could potentially be confused with MAS (active systemic JIA without evidence of MAS, or systemic infection). Next, the ability of candidate criteria to classify individual patients as having MAS or not having MAS was assessed by evaluating the agreement between the classification yielded using the criteria and the consensus classification of the experts. The final criteria were selected in a consensus conference. Experts achieved consensus on the classification of 391 of the 428 patient profiles (91.4%). A total of 982 candidate criteria were tested statistically. The 37 best-performing criteria and 8 criteria obtained from the literature were evaluated at the consensus conference. During the conference, 82% consensus among experts was reached on the final MAS classification criteria. In validation analyses, these criteria had a sensitivity of 0.73 and a specificity of 0.99. Agreement between the classification (MAS or not MAS) obtained using the criteria and the original diagnosis made by the treating physician was high (κ=0.76). We have developed a set of classification criteria for MAS complicating systemic JIA and provided preliminary evidence of its validity. Use of these criteria will potentially improve understanding of MAS in systemic JIA and enhance efforts to discover effective therapies, by ensuring appropriate patient enrollment in studies.

Germline ETV6 Mutations Confer Susceptibility to Acute Lymphoblastic Leukemia and Thrombocytopenia

Somatic mutations affecting ETV6 often occur in acute lymphoblastic leukemia (ALL), the most common childhood malignancy. The genetic factors that predispose to ALL remain poorly understood. Here we identify a novel germline ETV6 p. L349P mutation in a kindred affected by thrombocytopenia and ALL. A second ETV6 p. N385fs mutation was identified in an unrelated kindred characterized by thrombocytopenia, ALL and secondary myelodysplasia/acute myeloid leukemia. Leukemic cells from the proband in the second kindred showed deletion of wild type ETV6 with retention of the ETV6 p. N385fs. Enforced expression of the ETV6 mutants revealed normal transcript and protein levels, but impaired nuclear localization. Accordingly, these mutants exhibited significantly reduced ability to regulate the transcription of ETV6 target genes. Our findings highlight a novel role for ETV6 in leukemia predisposition.

Consensus recommendations for the diagnosis and management of hemophagocytic lymphohistiocytosis associated with malignancies.

The hyperinflammatory syndrome hemophagocytic lymphohistiocytosis can occur in the context of malignancies. Malignancy-triggered hemophagocytic lymphohistiocytosis should be regarded seperately from hemophagocytic lymphohistiocytosis during chemotherapeutic treatment, which is frequently associated with an infectious trigger. The substantial overlap between the features of hemophagocytic lymphohistiocytosis with features of neoplasms makes its identification difficult when it occurs in malignant conditions. To facilitate recognition and diagnostic workup, and provide guidance regarding the treatment of malignancy-associated hemophagocytic lymphohistiocytosis, consensus recommendations were developed by the Study Group on Hemophagocytic Lymphohistiocytosis Subtypes of the Histiocyte Society, an interdisciplinary group consisting of pediatric and adult hemato-oncologists and immunologists.

Germline genetic variation in ETV6 and risk of childhood acute lymphoblastic leukaemia: a systematic genetic study

Background Hereditary predisposition is rarely suspected for childhood acute lymphoblastic leukemia (ALL). Recent studies identified germline ETV6 variations associated with marked familial clustering of hematologic malignancies, pointing to this gene as a potentially important genetic determinant for ALL susceptibility. The aims of the current study are to comprehensively identify ALL predisposition variants in ETV6 and to determine the extent to which they contribute to the overall risk of childhood ALL. Methods Whole-exome sequencing of an index family with multiple cases of ALL was performed to identify causal variants for ALL predisposition. Targeted sequencing of ETV6 was done in 4,405 children from the Childrens Oncology Group (COG) and St. Jude Childrens Research Hospital frontline ALL trials. Patients were included in this study on the basis of their enrollment in these clinical trials and the availability of germline DNA. ETV6 variant genotypes were compared with non-ALL controls to define ALL-related germline risk variants. ETV6 variant function was characterized bioinformatically and correlated with clinical and demographic features in 2,021 children with ALL. Findings We identified a novel nonsense ETV6 variant (p.R359X) with a high penetrance of familial ALL. Subsequent targeted sequencing of ETV6 in 4,405 childhood ALL cases discovered 31 exonic variants (4 nonsense, 21 missense, 1 splice site, and 5 frame shift variants) that are potentially related to ALL risk in 35 cases (0.79%). Fifteen (48%) of the 31 ALL-related ETV6 variants clustered in the ETS domain and predicted to be highly deleterious. Children with ALL-related ETV6 variants were significantly older at leukemia diagnosis than others (10.2 years [IQR 5.3-13.8] vs 4.7 years [IQR 3.0-8.7], P=0.017). The hyperdiploid leukemia karyotype was strikingly overrepresented in ALL cases harboring germline ETV6 risk variants compared to the wildtype group (9 of 14 cases [64.3%] vs 538 of 2,007 cases [26.8%]; P=0.0050). Interpretation Our findings indicated germline ETV6 variations as the basis of a novel genetic syndrome associated with predisposition to childhood ALL. Funding This study was supported by the National Institutes of Health and by the American Lebanese Syrian Associated Charities.

Development and initial validation of classification criteria for macrophage activation syndrome complicating systemic juvenile idiopathic arthritis

To develop criteria for the classification of macrophage activation syndrome (MAS) in patients with systemic juvenile idiopathic arthritis (JIA).

Janus kinase inhibition lessens inflammation and ameliorates disease in murine models of hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) comprises an emerging spectrum of inherited and noninherited disorders of the immune system characterized by the excessive production of cytokines, including interferon-γ and interleukins 2, 6, and 10 (IL-2, IL-6, and IL-10). The Janus kinases (JAKs) transduce signals initiated following engagement of specific receptors that bind a broad array of cytokines, including those overproduced in HLH. Based on the central role for cytokines in the pathogenesis of HLH, we sought to examine whether the inhibition of JAK function might lessen inflammation in murine models of the disease. Toward this end, we examined the effects of JAK inhibition using a model of primary (inherited) HLH in which perforin-deficient (Prf1(-∕-)) mice are infected with lymphocytic choriomeningitis virus (LCMV) and secondary (noninherited) HLH in which C57BL/6 mice receive repeated injections of CpG DNA. In both models, treatment with the JAK1/2 inhibitor ruxolitinib significantly lessened the clinical and laboratory manifestations of HLH, including weight loss, organomegaly, anemia, thrombocytopenia, hypercytokinemia, and tissue inflammation. Importantly, ruxolitinib treatment also significantly improved the survival of LCMV-infectedPrf1(-∕-)mice. Mechanistic studies revealed that in vivo exposure to ruxolitinib inhibited signal transducer and activation of transcription 1-dependent gene expression, limited CD8(+)T-cell expansion, and greatly reduced proinflammatory cytokine production, without effecting degranulation and cytotoxic function. Collectively, these findings highlight the JAKs as novel, druggable targets for mitigating the cytokine-driven hyperinflammation that occurs in HLH. These observations also support the incorporation of JAK inhibitors such as ruxolitinib into future clinical trials for patients with these life-threatening disorders.

Malignancy‐associated haemophagocytic lymphohistiocytosis in children and adolescents

Haemophagocytic lymphohistiocytosis (HLH) in the context of malignancy is mainly considered a challenge of adult haematology. While this association is also observed in children, little is known regarding inciting factors, appropriate treatment and prognosis. We retrospectively analysed 29 paediatric and adolescent patients for presenting features, type of neoplasm or preceding chemotherapy, treatment and outcome. Haemophagocytic lymphohistiocytosis was considered triggered by the malignancy (M‐HLH) in 21 patients, most of whom had T‐ (n = 12) or B‐cell neoplasms (n = 7), with Epstein–Barr virus as a co‐trigger in five patients. In eight patients, HLH occurred during chemotherapy (Ch‐HLH) for malignancy, mainly acute leukaemias (n = 7); an infectious trigger was found in seven. In M‐ and Ch‐HLH, median overall survival was 1·2 and 0·9 years, and the 6 month survival rates were 67% and 63%, respectively. Seven of 11 deceased M‐HLH patients exhibited active malignancy and HLH at the time of death, while only two out of five deceased Ch‐HLH patients had evidence of active HLH. To overcome HLH, malignancy‐ and HLH‐directed treatments were administered in the M‐HLH cohort; however, it was not possible to determine superiority of one approach over the other. For Ch‐HLH, treatment ranged from postponement of chemotherapy to the use of etoposide‐containing regimens.

Prevalence of germline truncating mutations in ATM in women with a second breast cancer after radiation therapy for a contralateral tumor.

Patients treated with conservative surgery and radiation therapy for early‐stage breast cancer develop a contralateral breast cancer at a rate of approximately 0.75% per year. Ataxia‐telangiectasia (AT) is an autosomal recessive disease that is characterized by increased sensitivity to ionizing radiation (IR) and cancer susceptibility. Epidemiologic studies have suggested that AT carriers, who comprise 1% of the population, may be at an increased risk for developing breast cancer, particularly after exposure to IR. To test this hypothesis, we analyzed blood samples from 57 patients who developed a contralateral breast cancer at least 6 months after completion of radiation therapy for an initial breast tumor. A cDNA‐based truncation assay in yeast was used to test for heterozygous mutations in the ATM gene, which is responsible for AT. No mutations were detected. Our findings fail to support the hypothesis that AT carriers account for a significant fraction of breast cancer cases arising in women after exposure to radiation. Genes Chromosomes Cancer 27:124–129, 2000.