[Current Status and Perspective of Medical Setting for Pediatric Cancers in Japan].

In accordance with the Basic Plan to Promote Cancer Control Programs, a medical setting for providing patients with pediatric cancers sufficient medical treatments and supports has been assigned as one of the central issues in Japan. The Japanese Ministry of Health, Labour and Welfare designated 15 Pediatric Cancer Core Hospitals, and National Center for Child Health and Development as a central center in February 2013. A medical setting for pediatric cancers has been progressed to achieve the consolidation of patients who need specialized therapies and equalization of patients who need standard therapies for cure. Pediatric cancers are typical rare cancers in terms of the disease frequency. Therefore, there is a limitation to conduct systemic clinical studies in a few centers. To overcome this situation, JCCG(Japanese Children's Cancer Group)and JPLSG(Japanese Pediatric Leukemia/Lymphoma Study Group)were organized to conduct more than 30 clinical studies nationwide in each disease of pediatric solid tumors and hematological malignancies, respectively. They contributed to better outcome achieving more than 80% overall survival rates. While clinical trials to reduce therapeutic intensity in patients with better prognosis, molecular targeted therapies based on comprehensive genetic analysis and CAR-T therapy have been provided as effective therapeutic options in patients with refractory diseases. However, we still have limitations to provide patients such new therapeutic agents without delay covered by health insurance. Comprehensive supportive care for the patients and their family members by multi-disciplinary medical stuffs are required for their better quality of life. Long-term follow-ups for cancer survivors, learning supporting system for high school students, cares for their siblings, supports for the generation of adolescent and young adults (AYA) and fertility preservation have been provided in each hospital. In this paper, I summarized these current status and future perspective for medical settings of pediatric cancers in Japan.

Stage M Infantile Neuroblastoma With Involvement of Falx Cerebri: Case Report and Literature Review.

Neuroblastoma is the most common extracranial solid tumor in children. When metastasis to the falx cerebri is present, it is classified as stage M; however, its behavior has not been well characterized. Here we present a case of stage M infantile neuroblastoma (NB) with involvement of the falx cerebri, and also summarize the clinical profiles of previously reported cases. Notably, all of the tumors resolved with low-dose chemotherapy alone. Although further study is needed to distinguish NBs presenting at these different intracranial locations, NB with metastasis to the falx cerebri may be categorized as MS when diagnosed at less than 18 months of age.

Factors associated with employment status among mothers of survivors of childhood cancer: a cross-sectional study.

PURPOSE: To identify the factors associated with employment status among mothers of childhood cancer survivors (CCSs). METHODS: We conducted a questionnaire survey on mothers of survivors of childhood cancer to clarify practical factors such as care demands, psychological factors such as motivation to work, and support. After calculating descriptive statistics for all variables, binary logistic regression analysis was performed. RESULTS: Of 171 mothers, 129 (75.4%) were employed. The most common form of employment was non-regular (n = 83; 48.5%), including part-time, dispatched, and fixed-term workers. At the time of the survey, compared with nonworking mothers, working mothers tended to be more motivated to work and have lower scores for "Long-term Uncertainty" on the Parent Experience of Child Illness Scale. The results of the binary logistic regression analysis indicated that employment was related to higher motivation to work, the continuation of employment during treatment, more outpatient visits, and a higher amount of support. CONCLUSION: As employment of CCSs' mothers is associated with psychological factors such as motivation to work and long-term uncertainty, psychological support for CCSs' mothers might promote employment. In addition, because the continuation of employment during treatment affects the employment of mothers after the end of cancer treatment, a leave system that covers the treatment period for childhood cancer needs to be established.

Novel POLE mutations identified in patients with IMAGE-I syndrome cause aberrant subcellular localisation and protein degradation in the nucleus.

BACKGROUND: DNA replisome is a molecular complex that plays indispensable roles in normal DNA replication. IMAGE-I syndrome is a DNA replisome-associated genetic disease caused by biallelic mutations in the gene encoding DNA polymerase epsilon catalytic subunit 1 (POLE). However, the underlying molecular mechanisms remain largely unresolved. METHODS: The clinical manifestations in two patients with IMAGE-I syndrome were characterised. Whole-exome sequencing was performed and altered mRNA splicing and protein levels of POLE were determined. Subcellular localisation, cell cycle analysis and DNA replication stress were assessed using fibroblasts and peripheral blood from the patients and transfected cell lines to determine the functional significance of POLE mutations. RESULTS: Both patients presented with growth retardation, adrenal insufficiency, immunodeficiency and complicated diffuse large B-cell lymphoma. We identified three novel POLE mutations: namely, a deep intronic mutation, c.1226+234G>A, common in both patients, and missense (c.2593T>G) and in-frame deletion (c.711_713del) mutations in each patient. The unique deep intronic mutation produced aberrantly spliced mRNAs. All mutants showed significantly reduced, but not null, protein levels. Notably, the mutants showed severely diminished nuclear localisation, which was rescued by proteasome inhibitor treatment. Functional analysis revealed impairment of cell cycle progression and increase in the expression of phospho-H2A histone family member X in both patients. CONCLUSION: These findings provide new insights regarding the mechanism via which POLE mutants are highly susceptible to proteasome-dependent degradation in the nucleus, resulting in impaired DNA replication and cell cycle progression, a characteristic of DNA replisome-associated diseases.

Impairment of cytokine production following immunological synapse formation in patients with Wiskott-Aldrich syndrome and leukocyte adhesion deficiency type 1.

T cells following immunological synapse (IS) formation with antigen-presenting cells produce multiple cytokines through T cell receptor, integrin, and costimulatory signaling. Here, we investigated the cytokine profiles following IS formation in response to staphylococcal superantigen exposure in three adolescent patients with classical Wiskott-Aldrich syndrome (WAS) and in one patient with leukocyte adhesion deficiency (LAD) type 1. All WAS patients showed lower Th1 and Th2-skewed cytokine production; similar results were observed in the flow cytometric analysis of IFNγ- and IL-4-producing T cells. The patient with LAD type 1 with somatic mosaicism in 2% of CD8+ T cells showed lower Th1 and Th2 cytokine production than healthy controls. The patients with WAS were susceptible to infections and atopic manifestations, and the patients with LAD type 1 showed cold abscess on their skin, our findings using patient samples provide clinical insights into the mechanisms underlying immunodeficiency related to the symptoms of each disease.

The incidence of symptomatic osteonecrosis is similar between Japanese children and children in Western countries with acute lymphoblastic leukaemia treated with a Berlin-Frankfurt-Münster (BFM)95-based protocol.

In this study, we performed a retrospective analysis of a cohort of Japanese paediatric patients with B-cell precursor (BCP)-acute lymphoblastic leukaemia (ALL) treated with a Berlin-Frankfurt-Münster (BFM)95-based protocol, to clarify the incidence, clinical characteristics, and risk factors of osteonecrosis (ON) in comparison to the ALL-02 protocol. We identified a high frequency of ON with the BFM95-based protocol compared to the ALL-02 protocol. The incidence of symptomatic ON with the BFM95-based protocol is comparable to previous studies in Western countries. We believe that the type of treatment regimen has more impact on the incidence of symptomatic ON in paediatric ALL than ethnicity.

Hematopoietic Cell Transplantation for Inborn Errors of Immunity Other than Severe Combined Immunodeficiency in Japan: Retrospective Analysis for 1985-2016.

PURPOSE: Hematopoietic cell transplantation (HCT) is a curative therapy for most patients with inborn errors of immunity (IEI). We conducted a nationwide study on HCT for patients with IEI other than severe combined immunodeficiency (non-SCID) in Japan. METHODS: Data from the Japanese national database (Transplant Registry Unified Management Program, TRUMP) for 566 patients with non-SCID IEI, who underwent their first HCT between 1985 and 2016, were retrospectively analyzed. RESULTS: The 10-year overall survival (OS) and event-free survival (EFS) were 74% and 64%, respectively. The 10-year OS for HCT from unrelated bone marrow (URBM), accounting for 39% of HCTs, was comparable to that for HCT from matched sibling donor (MSD), 79% and 81%, respectively. HCT from unrelated cord blood (URCB), accounting for 28% of HCTs, was also common, with a 10-year OS of 69% but less robust engraftment. The intensity of conditioning was not associated with OS or neutrophil recovery; however, myeloablative conditioning was more frequently associated with infection-related death. Patients who received myeloablative irradiation showed poor OS. Multivariate analyses revealed that HCT in 1985-1995 (hazard ratio [HR], 2.0; P = 0.03), URCB (HR, 2.0; P = 0.01), and related donor other than MSD (ORD) (HR, 2.9; P < 0.001) were associated with poor OS, and URCB (HR, 3.6; P < 0.001) and ORD (HR, 2.7; P = 0.02) showed a higher incidence of retransplantation. CONCLUSIONS: We present the 1985-2016 status of HCT for non-SCID IEI in Japan with sufficient statistical power, highlighting the potential of URBM as an alternative donor and the feasibility of reduced intensity conditioning.

Registry data analysis of hematopoietic stem cell transplantation on systemic chronic active Epstein-Barr virus infection patients in Japan.

The effects of allogeneic hematopoietic stem cell transplantation (allo-HSCT) on systemic chronic active Epstein-Barr virus infection (sCAEBV) are yet to be analyzed in a large number of patients. Using the Japanese registry database, Transplant Registry Unification Management Program, we investigated the outcomes of 102 sCAEBV patients who underwent allo-HSCT. The median age at HSCT was 21 years, and the three-year overall survival (3-year OS) rate was 72.5%. Of the 90 patients whose viral load after allo-HSCT was evaluated, 56 (62.2%) achieved a virological complete response, defined by the complete resolution of disease activity with a significant decrease in EBV-DNA in peripheral blood. The multivariate Cox proportional hazard model indicated that advanced age, in adolescents and young adults (AYA) (age, 15-39) and adults (age, ≥40 years) was a risk factor of poor OS. The hazard ratios (HRs) of the AYA and adult groups were 10.87 (95% confidence interval [CI]: 1.98-59.56, p = .006) and 15.93 (95% CI: 2.45-103.8, p = .004), respectively. Disease activity (HR 5.74), elevated soluble IL-2 receptor (sIL-2R) (≥ median, 691 U/mL) at HSCT (HR 6.93), and conditioning without radiotherapy (HR 3.53) were also independently associated with poor survival. Notably, 79% of radiotherapy doses were less than 6 Gy. Regardless of the presence of hemophagocytic lymphohistiocytosis, the group with a high sIL-2R level (≥2000 U/mL) showed a poorer prognosis. Although allo-HSCT is the only curative therapy for sCAEBV, treatment strategies need to be improved for high-risk patients, especially those with high levels of sIL-2R.

Outcome of children with relapsed high-risk neuroblastoma in Japan and analysis of the role of allogeneic hematopoietic stem cell transplantation.

BACKGROUND: In Japan, allogeneic hematopoietic stem cell transplantation is widely performed for recurrent neuroblastomas. This retrospective study aimed to investigate the prognosis of recurrent neuroblastoma in Japan and explore the effectiveness of allogeneic hematopoietic stem cell transplantation. METHODS: Clinical characteristics and data on the treatment of patients with high-risk neuroblastoma who experienced first progression between 2003 and 2010 after attaining complete remission or partial remission were collected from hospitals participating in the Japanese Neuroblastoma Research Group. RESULTS: Data from 61 patients who fulfilled these criteria were collected. The median interval from disease onset to first progression was 19 months (range, 7-65 months), whereas the median observation time of the surviving patients was 18 months (range, 1-69 months). All patients were treated with chemotherapy, where 22 and 3 patients received allogeneic and autologous hematopoietic stem cell transplantation, respectively. Seven patients were alive in second complete remission, and 39 died, including two in complete remission. The 3-year progression-free survival and overall survival rates were 15.3% (SE: 6.1%) and 16.9% (SE: 6.5%), respectively. For patients with allogeneic hematopoietic stem cell transplantation, the 3-year progression-free survival and overall survival were 28.3% (standard error, 12.0%) and 24.3% (standard error, 11.5%), respectively, and for patients without allogeneic hematopoietic stem cell transplantation, the 3-year progression-free survival and overall survival were 6.0% (standard error 5.5%) and 12.0% (standard error 7.6%), respectively. The duration of initial remission (≥ 18 months) and implementation of allogeneic hematopoietic stem cell transplantation were independently predictive of progression-free survival (P = 0.002 and P = 0.017), whereas for overall survival, only allogeneic hematopoietic stem cell transplantation was predictive (P = 0.012). CONCLUSION: Although allogeneic hematopoietic stem cell transplantation contributed to some improvement in prognosis, it was insufficient.

Detailed analysis of Japanese patients with adenosine deaminase 2 deficiency reveals characteristic elevation of type II interferon signature and STAT1 hyperactivation.

BACKGROUND: Deficiency of adenosine deaminase 2 (DADA2) is an autosomal recessive inflammatory disease caused by loss-of-function mutations in both alleles of the ADA2 gene. Most patients with DADA2 exhibit systemic vasculopathy consistent with polyarteritis nodosa, but large phenotypic variability has been reported, and the pathogenesis of DADA2 remains unclear. OBJECTIVES: This study sought to assess the clinical and genetic characteristics of Japanese patients with DADA2 and to gain insight into the pathogenesis of DADA2 by multi-omics analysis. METHODS: Clinical and genetic data were collected from 8 Japanese patients with DADA2 diagnosed between 2016 and 2019. ADA2 variants in this cohort were functionally analyzed by in vitro overexpression analysis. PBMCs from 4 patients with DADA2 were subjected to transcriptome and proteome analyses. Patient samples were collected before and after introduction of anti- TNF-α therapies. Transcriptome data were compared with those of normal controls and patients with other autoinflammatory diseases. RESULTS: Five novel ADA2 variants were identified in these 8 patients and were confirmed pathogenic by in vitro analysis. Anti-TNF-α therapy controlled inflammation in all 8 patients. Transcriptome and proteome analyses showed that upregulation of type II interferon signaling was characteristic of DADA2. Network analysis identified STAT1 as a key regulator and a hub molecule in DADA2 pathogenesis, a finding supported by the hyperactivation of STAT1 in patients' monocytes and B cells after IFN-γ stimulation. CONCLUSIONS: Type II interferon signaling and STAT1 are associated with the pathogenesis of DADA2.

Hematopoietic Cell Transplantation for Severe Combined Immunodeficiency Patients: a Japanese Retrospective Study.

PURPOSE: Hematopoietic cell transplantation (HCT) is a curative therapy for patients with severe combined immunodeficiency (SCID). Here, we conducted a nationwide study to assess the outcome of SCID patients after HCT in Japan. METHODS: A cohort of 181 SCID patients undergoing their first allogeneic HCT in 1974-2016 was studied by using the Japanese national database (Transplant Registry Unified Management Program, TRUMP). RESULTS: The 10-year overall survival (OS) of the patients who received HCT in 2006-2016 was 67%. Umbilical cord blood (UCB) transplantation was performed in 81 patients (45%). The outcomes of HCT from HLA-matched UCB (n = 21) and matched sibling donors (n = 22) were comparable, including 10-year OS (91% vs. 91%), neutrophil recovery (cumulative incidence at 30 days, 89% vs. 100%), and platelet recovery (cumulative incidence at 60 days, 89% vs. 100%). Multivariate analysis of the patients who received HCT in 2006-2016 demonstrated that the following factors were associated with poor OS: bacterial or fungal infection at HCT (hazard ratio (HR): 3.8, P = 0.006), cytomegalovirus infection prior to HCT (HR: 9.4, P = 0.03), ≥ 4 months of age at HCT (HR: 25.5, P = 0.009), and mismatched UCB (HR: 19.8, P = 0.01). CONCLUSION: We showed the potential of HLA-matched UCB as a donor source with higher priority for SCID patients. We also demonstrated that early age at HCT without active infection is critical for a better prognosis, highlighting the importance of newborn screening for SCID.

[Congenital thrombocytopenia].

Congenital thrombocytopenia is a group of heterogeneous disorders caused by mutations in the responsible genes that play crucial roles in normal megakaryopoiesis and subsequent platelet production. The diagnosis of congenital thrombocytopenia is clinically necessary to distinguish it from immune thrombocytopenia and select the appropriate therapeutic modalities. The number of responsible genes reported so far is up to 56, and data on their targeted sequencing and subsequent exome sequencing analysis are available in Japan. Here, we report the disease outlines, disease classification based on platelet sizes (small, normal, large, and giant platelets), disease descriptions, consultation system, list of responsible genes, therapeutic options, and follow-up system for congenital thrombocytopenia.

Correction to: the IL1RN Mutation Creating the Most-Upstream Premature Stop Codon Is Hypomorphic because of a Reinitiation of Translation.

The original version of our manuscript, entitled, " The IL1RN mutation creating the most-upstream premature stop codon is hypomorphic because of a reinitiation of translation" unfortunately contained mistakes in Fig. 1a and d legends. The text should read as follows.

Improvement of native pulmonary alveolar proteinosis after contralateral single living-donor lobar lung transplantation: A case report.

PAP is a rare disease characterized by the accumulation of surfactant materials in the alveolar spaces due to the imbalance of surfactant homeostasis (production and clearance). We herein report a case of an 8-year-old girl who developed PAP after BMT from her mother for the treatment of DBA. The anemia was improved by BMT; however, respiratory dysfunction due to graft-versus-host disease gradually progressed. She eventually underwent right single LDLLT from her mother when she was 14 years old. A pathological examination of the excised lung confirmed the finding of diffuse bronchiolitis obliterans and unexpectedly revealed widespread alveolar proteinosis. Interestingly, the GGO of her native left lung on chest X-ray was improved after LDLLT. We present the very unique clinical course of this patient and discuss the mechanisms underlying the development of PAP after BMT and its improvement after LDLLT from the same donor.

Comprehensive Targeted Sequencing Identifies Monogenic Disorders in Patients With Early-onset Refractory Diarrhea.

OBJECTIVES: Causes of early-onset refractory diarrhea include exudative diarrhea associated with very early-onset inflammatory bowel diseases, osmotic or secretory diarrhea, and protein-losing enteropathy. Monogenic disorders are included in these diseases, yet a comprehensive genetic analysis has not been fully established. METHODS: We established targeted gene panels covering all responsible genes for early-onset diarrhea. In total, 108 patients from 15 institutions were enrolled in this study. We collected clinical data from all patients. Seventy-three patients with exudative diarrhea, 4 with osmotic or secretory diarrhea and 8 with protein-losing enteropathy were subjected to genetic analysis. RESULTS: A total of 15 out of the 108 enrolled patients (13.9%) were identified as monogenic. We identified 1 patient with RELA, 2 with TNFAIP3, 1 with CTLA4, 1 with SLCO2A1, 4 with XIAP, 3 with IL10RA, 1 with HPS1, 1 with FOXP3, and 1 with CYBB gene mutations. We also identified 1 patient with NFKB2 and 1 with TERT mutations from the gene panel for primary immunodeficiency syndromes. The patient with refractory diarrhea caused by heterozygous truncated RelA protein expression is the first case identified worldwide, and functional analysis revealed that the mutation affected nuclear factor kappa B signaling. Genotypes were significantly associated with the clinical and pathological findings in each patient. CONCLUSIONS: We identified variable monogenic diseases in the patients and found that genes responsible for primary immunodeficiency diseases were frequently involved in molecular pathogenesis. Comprehensive genetic analysis was useful for accurate molecular diagnosis, understanding of underlying pathogenesis, and selecting the optimal treatment for patients with early-onset refractory diarrhea.An infographic for this article is available at: http://links.lww.com/MPG/B853.

Infantile-onset inflammatory bowel disease in a patient with Hermansky-Pudlak syndrome: a case report.

BACKGROUND: Hermansky-Pudlak syndrome (HPS) is a rare, genetically heterogeneous disorder that manifests oculocutaneous albinism together with bleeding diatheses that reflect a platelet storage pool deficiency. Ten genetic subtypes of this autosomal recessive condition have been described to date. Some patients with Hermansky-Pudlak syndrome type 1, 4, or 6 develop Crohn's-like inflammatory bowel disease at any age including early childhood, but most often in adolescence or young adulthood. Here we report infantile-onset of inflammatory bowel disease in a patient with Hermansky-Pudlak syndrome type 1 who responded to infliximab. CASE PRESENTATION: A Japanese boy, the second child of non-consanguineous healthy parents, was born with chalky white skin, silvery-white hair, and gray eyes, representing oculocutaneous albinism. He developed frequent diarrhea and fever accompanied by weight loss at 6 months, and was diagnosed with Crohn's-like inflammatory bowel disease based on the endoscopic finding of longitudinal ulcerations in the colon and the histopathologic finding of nonspecific chronic inflammation without granulomas at the age of 11 months. Treatment with an elemental diet, salazosulfapyridine, and corticosteroids failed to improve clinical or laboratory abnormalities, and the diarrhea became bloody. At 13 months he began treatment with infliximab, which produced marked improvement followed by clinical remission. Endoscopy at 20 months demonstrated healing of the colonic mucosa. At 22 months he is in sustained clinical remission receiving only infliximab. Because albinism with inflammatory bowel disease suggested Hermansky-Pudlak syndrome, we performed genetic screening using next-generation sequencing in a targeted gene panel analysis for primary immunodeficiency disease and/or inflammatory bowel disease. The patient proved to have a compound heterozygous mutation of the HPS1 gene resulting in Hermansky-Pudlak syndrome type 1. CONCLUSIONS: We consider this report to be the first account of type 1 Hermansky-Pudlak syndrome with infantile-onset of inflammatory bowel disease. Early administration of infliximab was effective. We recommend next-generation sequencing for patients with very early-onset inflammatory bowel disease suspected to be monogenic.

Mechanisms of genotype-phenotype correlation in autosomal dominant anhidrotic ectodermal dysplasia with immune deficiency.

BACKGROUND: Autosomal dominant anhidrotic ectodermal dysplasia with immune deficiency (AD EDA-ID) is caused by heterozygous point mutations at or close to serine 32 and serine 36 or N-terminal truncations in IκBα that impair its phosphorylation and degradation and thus activation of the canonical nuclear factor κ light chain enhancer of activated B cells (NF-κB) pathway. The outcome of hematopoietic stem cell transplantation is poor in patients with AD EDA-ID despite achievement of chimerism. Mice heterozygous for the serine 32I mutation in IκBα have impaired noncanonical NF-κB activity and defective lymphorganogenesis. OBJECTIVE: We sought to establish genotype-phenotype correlation in patients with AD EDA-ID. METHODS: A disease severity scoring system was devised. Stability of IκBα mutants was examined in transfected cells. Immunologic, biochemical, and gene expression analyses were performed to evaluate canonical and noncanonical NF-κB signaling in skin-derived fibroblasts. RESULTS: Disease severity was greater in patients with IκBα point mutations than in those with truncation mutations. IκBα point mutants were expressed at significantly higher levels in transfectants compared with truncation mutants. Canonical NF-κB-dependent IL-6 secretion and upregulation of the NF-κB subunit 2/p100 and RELB proto-oncogene, NF-κB subunit (RelB) components of the noncanonical NF-κB pathway were diminished significantly more in patients with point mutations compared with those with truncations. Noncanonical NF-κB-driven generation of the transcriptionally active p100 cleavage product p52 and upregulation of CCL20, intercellular adhesion molecule 1 (ICAM1), and vascular cell adhesion molecule 1 (VCAM1), which are important for lymphorganogenesis, were diminished significantly more in LPS plus α-lymphotoxin ß receptor-stimulated fibroblasts from patients with point mutations compared with those with truncations. CONCLUSIONS: IκBα point mutants accumulate at higher levels compared with truncation mutants and are associated with more severe disease and greater impairment of canonical and noncanonical NF-κB activity in patients with AD EDA-ID.

Mutations in MECOM, Encoding Oncoprotein EVI1, Cause Radioulnar Synostosis with Amegakaryocytic Thrombocytopenia.

Radioulnar synostosis with amegakaryocytic thrombocytopenia (RUSAT) is an inherited bone marrow failure syndrome, characterized by thrombocytopenia and congenital fusion of the radius and ulna. A heterozygous HOXA11 mutation has been identified in two unrelated families as a cause of RUSAT. However, HOXA11 mutations are absent in a number of individuals with RUSAT, which suggests that other genetic loci contribute to RUSAT. In the current study, we performed whole exome sequencing in an individual with RUSAT and her healthy parents and identified a de novo missense mutation in MECOM, encoding EVI1, in the individual with RUSAT. Subsequent analysis of MECOM in two other individuals with RUSAT revealed two additional missense mutations. These three mutations were clustered within the 8(th) zinc finger motif of the C-terminal zinc finger domain of EVI1. Chromatin immunoprecipitation and qPCR assays of the regions harboring the ETS-like motif that is known as an EVI1 binding site showed a reduction in immunoprecipitated DNA for two EVI1 mutants compared with wild-type EVI1. Furthermore, reporter assays showed that MECOM mutations led to alterations in both AP-1- and TGF-ß-mediated transcriptional responses. These functional assays suggest that transcriptional dysregulation by mutant EVI1 could be associated with the development of RUSAT. We report missense mutations in MECOM resulting in a Mendelian disorder that provide compelling evidence for the critical role of EVI1 in normal hematopoiesis and in the development of forelimbs and fingers in humans.