Characterization and genotype-phenotype correlation of patients with Fanconi anemia in a multi-ethnic population

Fanconi anemia (FA), an inherited bone marrow failure (BMF) syndrome, caused by mutations in DNA repair genes, is characterized by congenital anomalies, aplastic anemia, high risk of malignancies and extreme sensitivity to alkylating agents. We aimed to study the clinical presentation, molecular diagnosis and genotype-phenotype correlation among patients with FA from the Israeli inherited BMF registry. Overall, 111 patients of Arab (57%) and Jewish (43%) descent were followed for a median of 15 years (range: 0.1-49); 63% were offspring of consanguineous parents. One-hundred patients (90%) had at least one congenital anomaly; over 80% of the patients developed bone marrow failure; 53% underwent hematopoietic stem-cell transplantation; 33% of the patients developed cancer; no significant association was found between hematopoietic stem-cell transplant and solid tumor development. Nearly 95% of the patients tested had confirmed mutations in the Fanconi genes FANCA (67%), FANCC (13%), FANCG (14%), FANCJ (3%) and FANCD1 (2%), including twenty novel mutations. Patients with FANCA mutations developed cancer at a significantly older age compared to patients with mutations in other Fanconi genes (mean 18.5 and 5.2 years, respectively, P=0.001); however, the overall survival did not depend on the causative gene. We hereby describe a large national cohort of patients with FA, the vast majority genetically diagnosed. Our results suggest an older age for cancer development in patients with FANCA mutations and no increased incidence of solid tumors following hematopoietic stem-cell transplant. Further studies are needed to guide individual treatment and follow-up programs

Syndromes predisposing to leukemia are a major cause of inherited cytopenias in children

Prolonged cytopenias are a non-specific sign with a wide differential diagnosis. Among inherited disorders, cytopenias predisposing to leukemia require a timely and accurate diagnosis to ensure appropriate medical management, including adequate monitoring and stem cell transplantation prior to the development of leukemia. We aimed to define the types and prevalences of the genetic causes leading to persistent cytopenias in children. The study comprises children with persistent cytopenias, myelodysplastic syndrome, aplastic anemia, or suspected inherited bone marrow failure syndromes, who were referred for genetic evaluation from all pediatric hematology centers in Israel during 2016-2019. For variant detection, we used Sanger sequencing of commonly mutated genes and a custom-made targeted next-generation sequencing panel covering 226 genes known to be mutated in inherited cytopenias; the minority subsequently underwent whole exome sequencing. In total, 189 children with persistent cytopenias underwent a genetic evaluation. Pathogenic and likely pathogenic variants were identified in 59 patients (31.2%), including 47 with leukemia predisposing syndromes. Most of the latter (32, 68.1%) had inherited bone marrow failure syndromes, nine (19.1%) had inherited thrombocytopenia predisposing to leukemia, and three each (6.4%) had predisposition to myelodysplastic syndrome or congenital neutropenia. Twelve patients had cytopenias with no known leukemia predisposition, including nine children with inherited thrombocytopenia and three with congenital neutropenia. In summary, almost one third of 189 children referred with persistent cytopenias had an underlying inherited disorder; 79.7% of whom had a germline predisposition to leukemia. Precise diagnosis of children with cytopenias should direct follow-up and management programs and may positively impact disease outcome

Mycoplasma pneumonia Infection: A Possible Trigger for Immune Thrombocytopenia

Mycoplasma pneumonia (M. pneumonia) is usually not considered among the several pathogens that induce immune thrombocytopenia (ITP). We report a child with a clinical diagnosis of severe ITP that was associated with M. pneumonia pneumonia, and review the few cases described in the English literature. We suggest that thrombocytopenia associated with M. pneumonia infection may constitute a subset of ITP, although unlike ITP it occurs concomitantly with the infection and tends to be more severe than “classic” ITP. We recommend that prompt specific antibiotic and immune modulating treatment should be initiated in appropriate clinical settings

Sinus Vein Thrombosis in Pediatric Patients After Acute Mastoiditis

BACKGROUND: Acute mastoiditis (AM), a complication of acute otitis media, remains a concern despite medical advancements and often leads to severe complications such as cerebral sinus vein thrombosis (CSVT). This study aimed to characterize the clinical, microbiological, and hematological aspects of CSVT secondary to AM in children while assessing the necessity of thrombophilia evaluation in these patients. METHODS: A retrospective analysis was conducted on pediatric patients with CSVT secondary to AM between January 2015 and December 2022. This study examined clinical data, laboratory and microbiological results, imaging studies, treatment approaches, and patient outcomes. RESULTS: Seventeen pediatric patients with a mean age of 3 years were included in this study. Most patients were female (76.5%) and of Jewish ethnicity (82.4%). Group A Streptococcus is the primary pathogen responsible for this condition. The treatment plan involved the administration of intravenous antibiotics and surgical intervention, including cortical mastoidectomy and ventilation tube insertion. Additionally, anticoagulation therapy with Clexane® was initiated and continued for at least 3 months post event. Follow-up imaging revealed recanalization in most cases within an average of 3 months. Hematologic follow-up revealed no recurrent thrombotic events and low thrombophilia incidence. CONCLUSION: Cerebral sinus vein thrombosis following AM is a provoked thrombotic event effectively managed with Clexane®. Thrombophilia evaluation may be reserved for patients with a high suspicion of underlying hematological conditions. Follow-up imaging within 3 months post event may be premature

Activating Mutation of STAT3 Protects Lymphocytes from Apoptosis and Leads to a Clinical Phenotype Resembling the Autoimmune Lymphoproliferative Syndrome

Abstract (PS and UF contributed equally to this work.) Introduction: The Autoimmune Lymphoproliferative Syndrome (ALPS) is caused by inefficient clearing of T lymphocytes. Patients are thus characterized by lymphadenopathy, hepatosplenomegaly, autoimmune cytopenias and an elevated number of double negative T cells (CD3+, TCRα/β+, CD4-, CD8-). Patients suffering from ALPS typically harbor germline or somatic mutations in genes involved in the apoptotic FAS death receptor signaling pathway (FAS, FASLG or CASP10). For 20-30% of patients, however, the genetic cause is still unknown. Methods: The objective of this study was to identify novel gene candidates underlying ALPS of unknown genetic cause. To this end, 25 patients with clinical ALPS symptoms, but without classical mutations were analyzed by whole-exome sequencing. The list of potential candidates was narrowed down using an in-house developed bioinformatic analysis pipeline for patient-based gene prioritization based on protein-protein interaction networks. Resulting candidates were validated by Sanger sequencing and their impact on Fas signaling was studied. Results We identified a de novo germline mutation of the Signal Transducer And Activator Of Transcription 3 (STAT3, c.833G&gt;A, p.R278H) in one of the analyzed patients. The patient presented at the age of nine with Coombs positive hemolytic anemia, thrombocytopenia, generalized progressive, non-infectious, non-malignant lymphadenopathy and splenomegaly. Immunophenotyping revealed increased numbers of double negative T cells (20% in peripheral blood) and over time the patient developed panhypogammaglobulinemia. We performed immunoblot analyses and could demonstrate that the level of phosphorylated STAT3 (pSTAT3-Tyr705) was elevated in the patient's lymphocytes. This finding indicated that the mutation leads to constitutive activation of STAT3. Consistently, we detected an increased expression of STAT3 target genes (including SOCS3, MMP7 and the anti-apoptotic factors BCL2 and BCL2L1) compared to wild-type controls using quantitative real-time PCR. We could also show a decreased expression of the pro-apoptotic genes BAK1 and BAX that is in accordance with the known negative regulation by STAT3. Thus, in the analyzed patient we found that the balance of pro- and anti-apoptotic factors inside the cell was skewed towards apoptosis resistance. Consistently, we could induce apoptosis in vitro applying recombinant Fas ligand, IL21 or staurosporine efficiently in cells derived from healthy controls, but only to a significantly lesser extent in cells from the patient. Moreover, in healthy cells we observed a concurrent downregulation of anti-apoptotic BCL2/BCL2L1 and an upregulation of pro-apoptotic BAX/BAK1 expression upon treatment that was completely absent in the patient's cells. Next, we tried to rescue the effect of constitutively activated STAT3 by application of a STAT3 specific inhibitor: S3I-201. When we treated the patient's lymphocytes with S3I-201 the expression levels of pro- and anti-apoptotic genes were similar to healthy controls and the sensitivity to apoptosis was restored. Conclusion: We report here a novel germline dominant STAT3 gain-of-function mutation that caused a clinical phenotype mimicking ALPS. Recent studies indicated that dominant germline STAT3 gain-of-function mutations lead to autoimmunity, hypogammaglobulinemia, and lymphoproliferation. STAT3 gain-of-function patients therefore share some clinical characteristics with ALPS patients. The clinical presentation of the patient described here differed from the phenotypes previously reported and thus extends the spectrum of STAT3 -associated diseases. The mechanism underlying the clinical symptoms of STAT3 gain-of-function patients has not yet been determined. Here, we demonstrate increased activation of STAT3 and STAT3 target genes, leading to a skewed balance of pro- and anti-apoptotic factors and apoptosis evasion as a cause for lymphocyte accumulation and resulting autoimmunity in a STAT3 gain-of-function patient. Similar to ALPS patients, diminished responsiveness of lymphocytes to apoptosis seems to be a major characteristic. The clinical phenotype may differ because mutations in STAT3 or Fas signaling genes, respectively, affect overlapping, but also distinct signaling pathways. Disclosures No relevant conflicts of interest to declare. </jats:sec