Haploinsufficiency in PTPN2 leads to early-onset systemic autoimmunity from Evans syndrome to lupus.

An exome sequencing strategy employed to identify pathogenic variants in patients with pediatric-onset systemic lupus or Evans syndrome resulted in the discovery of six novel monoallelic mutations in PTPN2. PTPN2 is a phosphatase that acts as an essential negative regulator of the JAK/STAT pathways. All mutations led to a loss of PTPN2 regulatory function as evidenced by in vitro assays and by hyperproliferation of patients' T cells. Furthermore, patients exhibited high serum levels of inflammatory cytokines, mimicking the profile observed in individuals with gain-of-function mutations in STAT factors. Flow cytometry analysis of patients' blood cells revealed typical alterations associated with autoimmunity and all patients presented with autoantibodies. These findings further supported the notion that a loss of function in negative regulators of cytokine pathways can lead to a broad spectrum of autoimmune manifestations and that PTPN2 along with SOCS1 haploinsufficiency constitute a new group of monogenic autoimmune diseases that can benefit from targeted therapy.

Predicting survival in patients with myelodysplastic/myeloproliferative neoplasms with SF3B1 mutation and thrombocytosis.

We investigated data from 180 consecutive patients with myelodysplastic/myeloproliferative neoplasms with SF3B1 mutation and thrombocytosis (MDS/MPN-SF3B1-T) who were diagnosed according to the 2022 World Health Organization (WHO) classification of myeloid neoplasms to identify covariates associated with survival. At a median follow-up of 48 months (95% confidence interval [CI] 35-61 months), the median survival was 69 months (95% CI 59-79 months). Patients with bone marrow ring sideroblasts (RS) < 15% had shorter median overall survival (OS) than did those with bone marrow RS ≥ 15% (41 months [95% CI 32-50 months] versus 76 months [95% CI 59-93 months]; P < 0.001). According to the univariable analyses of OS, age ≥ 65 years (P < 0.001), hemoglobin concentration (Hb) < 80 g/L (P = 0.090), platelet count (PLT) ≥ 800 × 10E + 9/L (P = 0.087), bone marrow RS < 15% (P < 0.001), the Revised International Prognostic Scoring System (IPSS-R) cytogenetic category intermediate/poor/very poor (P = 0.005), SETBP1 mutation (P = 0.061) and SRSF2 mutation (P < 0.001) were associated with poor survival. Based on variables selected from univariable analyses, two separate survival prediction models, a clinical survival model, and a clinical-molecular survival model, were developed using multivariable analyses with the minimum value of the Akaike information criterion (AIC) to specifically predict outcomes in patients with MDS/MPN-SF3B1-T according to the 2022 WHO classification.

Idiopathic Thrombocytosis in Alpha Thalassemia Trait Patient.

Platelet count increases are typically a reactionary response to one of a variety of pathophysiological events. We present here a case of microcytic hypochromic red blood cells and thrombocytosis in an adolescent female that we have monitored for three years. The patient was positive for alpha thalassemia trait; negative for mutation in Janus kinase 2, calreticulin, or myeloproliferative leukemia virus oncogene; and negative for reactive causes of thrombocytosis. Noticeably, a variant in atypical chemokine receptor 1 (ACKR1) (c.-67T>C, rs2814778) was found to be homozygous. Accordingly, the case was diagnosed as idiopathic thrombocytosis, and treatment was given to restore platelet levels to normal. Our findings highlight the possibility of an unknown association between alpha thalassemia trait and idiopathic thrombocytosis in the presence of ACKR1 mutation, which could be implicated in disease pathogenesis.

Relative impact of THPO mutation causing hereditary thrombocythemia.

Germline mutations of THPO were reported as causes of hereditary thrombocythemia. Six previously reported distinct sites of the mutation were clustered at the 5`-untranslated region or the exon 3 splicing donor site of the THPO gene. Each mutation was identified in an independent pedigree, and the differences between the mutations were not compared. We cloned six distinct THPO mutations (THPO c.-47delG, THPO c.-31G>T, THPO c.13G>A, THPO c.13+1G>A, THPO c.13+2T>C, and THPO c.13+5G>A) and compared the molecular mechanisms that underlie the increased production of THPO protein. At the transcript level, all of the mutations except THPO c.-47delG showed an exon 3 skipping transcript, including two mutations (THPO c.-31G>T and THPO c.13+5G>A) that were distant from the splicing donor site. THPO c.-47delG showed the same full-length transcript as that of the wild-type transcript. At the protein level, all mutations resulted in a higher level of production of thrombopoietin (THPO) protein compared with wild-type THPO. There are only two distinct patterns of mechanisms for increased production of THPO: exon 3 skipping that deleted upstream suppressive open reading frame (ORF)7 and one base deletion that shifted ORF7 to connect to the initial codon of THPO in-frame. The common mechanisms of hereditary thrombocytosis due to THPO mutations are unleashed THPO translations, which are usually suppressed by upstream out-of-frame ORF7.

Aleukemic Chronic Myeloid Leukemia Without Neutrophilia and Thrombocytosis: A Report From the BCR::ABL1 Pathology Group.

Chronic myeloid leukemia (CML) is characterized by leukocytosis with left-shifted neutrophilia, basophilia, eosinophilia, and variable thrombocytosis. However, extremely rare cases of patients with CML without significant leukocytosis and thrombocytosis (aleukemic phase [ALP] CML, or CML-ALP) have been reported. Due to its rarity and limited awareness, there remains a significant knowledge gap concerning the pathologic diagnosis, disease progression, and optimal patient management and outcomes. In this multi-institutional study, we investigated 31 patients with CML-ALP. Over half (54.8%) of patients had a history of or concurrent hematopoietic or nonhematopoietic malignancies. At time of diagnosis of CML-ALP, approximately 26.7% of patients exhibited neutrophilia, 56.7% had basophilia, and 13.3% showed eosinophilia. The median number of metaphases positive for t(9;22)(q34;q11.2) was 15, with a median of 38.5% of interphase nuclei positive for BCR::ABL1 by fluorescence in situ hybridization. The median BCR::ABL1 level was 26.14%. Remarkably, 14 (45.2%) patients were initially misdiagnosed or not diagnosed before karyotype or fluorescence in situ hybridization information for BCR::ABL1 became available. Twenty-five patients received tyrosine kinase inhibitors (TKIs). One patient developed blast crisis while on TKI treatment 8 months after initial diagnosis. With a median follow-up time of 46.1 months, 20 of 22 patients who received TKI therapy and had detailed follow-up information achieved complete cytogenetic remission or deeper, 15 achieved major molecular remission or deeper, and 10 achieved molecularly undetectable leukemia. In conclusion, given the frequent occurrence of prior or concurrent malignancies, aleukemic presentation, and low level of t(9;22)(q34;q11.2)/BCR::ABL1, misdiagnosis or delayed diagnosis is common among these patients. While these patients generally respond well to TKIs, rare patients may develop blastic transformation. It is therefore important for pathologists and hematologists to be aware of this highly unusual presentation of CML to ensure timely diagnosis and appropriate management.

Valoración de la mutación V617F del gen JAK2 en síndromes mieloproliferativos crónicos con cromosoma Filadelfia negativo / Evaluation of V617F mutation of JAK2 in negative chromosome Philadelphia chronic myeloproliferative disorders

Fundamento y objetivo: La mutación V617F en el gen de la tirosincinasa JAK2 está implicada en la génesis de algunos síndromes mieloproliferativos crónicos (SMP) como la policitemia vera (PV), la trombocitemia esencial (TE) y la mielofibrosis (MF) idiopática. Se ha valorado el papel diagnóstico de esta mutación en los SMP y se ha comparado con la formación espontánea de colonias eritroides (BFU-E-ESP). Pacientes y método: Se incluyó a 146 pacientes, de los que 81 presentaban SMP (27 PV, 28 TE, 11 MF y 15 leucemia mieloide crónica), 28 con eritrocitosis secundaria o trombocitosis reactiva, 8 SMP/síndromes mielodisplásicos y 29 con otras hemopatías. En 54 casos se valoró también la BFU-E-ESP. La fuente de las células hemopoyéticas para obtener ADN fue la sangre periférica en 122 pacientes, la médula ósea en 33, las unidades formadoras de colonias eritroides con estimulación con eritropoyetina en 14 y las BFU-E-ESP en 24. La mutación V617F se efectuó usando una reacción en cadena de la polimerasa específica de alelo. Resultados: El 96% de las PV, el 59% de las TE y el 63,6% de las MF presentaron dicha mutación. La concordancia diagnóstica entre BFU-E-ESP y la mutación fue excelente (índice kappa = 0,93; acuerdo en lo positivo del 97% y acuerdo en lo negativo del 95%). Se pudo valorar la mutación en 119 de los 122 pacientes en que se usó sangre periférica, en los 33 en que se usó médula ósea y en la mitad de aquellos en que se utilizaron las colonias eritroides como fuentes de ADN. Conclusiones: La mutación V617F del gen JAK2 está presente en casi todas las PV y en la mitad de las TE y de las MF. Hay una excelente concordancia entre la presencia de esta mutación y BFU-E-ESP. Finalmente, se puede usar diferentes fuentes celulares en la obtención de ADN para el estudio de esta mutación

Background and objective: Polycythemia vera (PV) and essential thrombocytemia (ET) are chronic myeloproliferative diseases (MPD) characterized by overactive hemopoiesis. A single point mutation of JAK2 (Val617Phe) has been detected in PV, ET and myelofibrosis (MF). The aim of this work was to investigate the JAK2 mutation in patients with MPD and to compare the results to those of the endogenous formation of BFU-E erythroid colonies (EEC). Finally, different sources of hematopoietic cells to obtain DNA were evaluated. Patients and method: In this work 146 patents were studied (81 MPD: 27 PV, 28 ET, 11 MF and 15 with myeloid chronic leukemia). Moreover, 28 patients showed secondary polycythemias or reactive thrombocytosis, 8 MPD/myelodysplastic syndromes and 29 other disorders. In 54 patients, EEC were also evaluated. Peripheral blood cells were used as source of DNA in 122 patients, bone marrow in 33, cells from BFU-E in 14 and cells from EEC in 24 patients. Their DNA samples were analyzed using an allele-specific polimerase chain reaction methodology. Results: The JAK2 mutation was present in 96% of PV patients, 59% of ET and 63.6% of MF. None of the remaining patients showed this mutation. Diagnostic agreement was excellent between EEC and the mutation (kappa index = 0.93; 97% positive agreement and 95% negative agreement). DNA was obtained in 119 out of 122 samples from peripheral blood, in all patients with bone marrow, and in 50% of patients with BFU-E or EEC. In 7 cases, samples from different cell sources were studied. Their results were identical. Conclusions: The V617F mutation of JAK2 is present in most of PV patients and half of those with MF or ET. There is an excellent concordance with the EEC results