Mcph1, mutated in primary microcephaly, is also crucial for erythropoiesis.

Microcephaly is a common feature in inherited bone marrow failure syndromes, prompting investigations into shared pathways between neurogenesis and hematopoiesis. To understand this association, we studied the role of the microcephaly gene Mcph1 in hematological development. Our research revealed that Mcph1-knockout mice exhibited congenital macrocytic anemia due to impaired terminal erythroid differentiation during fetal development. Anemia's cause is a failure to complete cell division, evident from tetraploid erythroid progenitors with DNA content exceeding 4n. Gene expression profiling demonstrated activation of the p53 pathway in Mcph1-deficient erythroid precursors, leading to overexpression of Cdkn1a/p21, a major mediator of p53-dependent cell cycle arrest. Surprisingly, fetal brain analysis revealed hypertrophied binucleated neuroprogenitors overexpressing p21 in Mcph1-knockout mice, indicating a shared pathophysiological mechanism underlying both erythroid and neurological defects. However, inactivating p53 in Mcph1-/- mice failed to reverse anemia and microcephaly, suggesting that p53 activation in Mcph1-deficient cells resulted from their proliferation defect rather than causing it. These findings shed new light on Mcph1's function in fetal hematopoietic development, emphasizing the impact of disrupted cell division on neurogenesis and erythropoiesis - a common limiting pathway.

Thirteen-month-old girl with hyporegenerative macrocytic anemia due to Brown-Vialetto-Van Laere syndrome 2.

We diagnosed a 13-month-old girl with severe neurological deficits and hyporegenerative macrocytic anemiawith Brown-Vialetto-Van Laere syndrome type 2 (BVVL 2), a rare disorder of the riboflavin transporter, caused by variants in the SLC52A2 gene. Bone marrow aspiration revealed hypoplastic erythropoiesis and vacuolization of myelocytes, proerythroblasts, and micromegakaryocytes. We suggest BVVL 2 as an important differential diagnosis in hyporegenerative macrocytic anemia as rapid diagnosis and initiation of therapy are crucial for the remedy of hematological and neurological impairment.

Clonal cytopenia of undetermined significance and atypical Behçet's: the importance of zinc.

Atypical Behçet's is recognised in myelodysplastic syndrome (MDS) cases and is associated with trisomy 8. Clonal cytopenia of undetermined significance (CCUS) is recognised as a precursor to MDS. Our case describes the presentation of atypical Behçet's, in association with CCUS, post a Streptococcal infection. A mutation of a zinc finger RNA spliceosome, ZRSR2, is also described. Our patient initially presented with macrocytic anaemia, together with neutropenia and lymphocytopenia on routine monitoring. Later gastrointestinal symptoms together with oral and anal ulcerations developed. He was treated with oral zinc therapy and had resolution of recurrent oral ulcerations and significant reduction in severity of anal ulcerations. The functional impact of ZRSR2 mutation on spliceosome assembly is yet to be defined, but has been previously reported in CCUS with a clinical phenotype of macrocytic anaemia.

5q11.2 deletion syndrome revisited-Further narrowing of the smallest region of overlap for the main clinical characteristics of the syndrome.

Microdeletions at 5q11.2 are rare. Subjects show a phenotypic spectrum that overlaps CHARGE syndrome and 22q11.2 deletion syndrome. A growing number of subjects present with learning difficulty and/or intellectual disability, immune deficiency, congenital heart malformation, and dysmorphism. DHX29 and IL6ST have been proposed as candidate genes for the development of the major clinical manifestations. We present a new case and narrow down the shortest region of overlap to evaluate possible candidate genes. Our case does not present developmental delay or immune deficiency indicating a reduced penetrance for some of the main clinical manifestations. The shortest region of overlap between subjects with deletions at 5q11.2 is approximately 450 kb (position 54.3-54.7 Mb). The narrowed region comprises 10 protein coding genes, including DHX29. DHX29 is a strong candidate gene for the main features of 5q11.2-microdeletion syndrome; however, our findings suggest a joined impact of several genes as the cause of the syndrome.

Stathmin 1 deficiency induces erythro-megakaryocytic defects leading to macrocytic anemia and thrombocythemia in Stathmin 1 knock out mice.

Stathmin 1 (STMN1) is a cytosolic phosphoprotein that was discovered as a result of its high level of expression in leukemic cells. It plays an important role in the regulation of mitosis by promoting depolymerization of the microtubules that make up the mitotic spindle and, aging has been shown to impair STMN1 levels and change microtubule stability. We have previously demonstrated that a high level of STMN1 expression during early megakaryopoiesis is necessary for proliferation of megakaryocyte progenitors and that down-regulation of STMN1 expression during late megakaryopoiesis is important for megakaryocyte maturation and platelet production. In this report, we examined the effects of STMN1 deficiency on erythroid and megakaryocytic lineages in the mouse. Our studies show that STMN1 deficiency results in mild thrombocytopenia in young animals which converts into profound thrombocythemia as the mice age. STMN1 deficiency also lead to macrocytic changes in both erythrocytes and megakaryocytes that persisted throughout the life of STMN1 knock-out mice. Furthermore, STMN1 knock-out mice displayed a lower number of erythroid and megakaryocytic progenitor cells and had delayed recovery of their blood counts after chemotherapy. These studies show an important role for STMN1 in normal erythro-megakaryopoietic development and suggests potential implications for disorders affecting these hematopoietic lineages.

Bcor deficiency perturbs erythro-megakaryopoiesis and cooperates with Dnmt3a loss in acute erythroid leukemia onset in mice.

Recurrent loss-of-function mutations of BCL6 co-repressor (BCOR) gene are found in about 4% of AML patients with normal karyotype and are associated with DNMT3a mutations and poor prognosis. Therefore, new anti-leukemia treatments and mouse models are needed for this combinatorial AML genotype. For this purpose, we first generated a Bcor-/- knockout mouse model characterized by impaired erythroid development (macrocytosis and anemia) and enhanced thrombopoiesis, which are both features of myelodysplasia/myeloproliferative neoplasms. We then created and characterized double Bcor-/-/Dnmt3a-/- knockout mice. Interestingly, these animals developed a fully penetrant acute erythroid leukemia (AEL) characterized by leukocytosis secondary to the expansion of blasts expressing c-Kit+ and the erythroid marker Ter119, macrocytic anemia and progressive reduction of the thrombocytosis associated with loss of Bcor alone. Transcriptomic analysis of double knockout bone marrow progenitors revealed that aberrant erythroid skewing was induced by epigenetic changes affecting specific transcriptional factors (GATA1-2) and cell-cycle regulators (Mdm2, Tp53). These findings prompted us to investigate the efficacy of demethylating agents in AEL, with significant impact on progressive leukemic burden and mice overall survival. Information gained from our model expands the knowledge on the biology of AEL and may help designing new rational treatments for patients suffering from this high-risk leukemia.

Hematologic presentation and the role of untargeted metabolomics analysis in monitoring treatment for riboflavin transporter deficiency.

Riboflavin transporter deficiency (RTD) (MIM #614707) is a neurogenetic disorder with its most common manifestations including sensorineural hearing loss, peripheral neuropathy, respiratory insufficiency, and bulbar palsy. Here, we present a 2-year-old boy whose initial presentation was severe macrocytic anemia necessitating multiple blood transfusions and intermittent neutropenia; he subsequently developed ataxia and dysarthria. Trio-exome sequencing detected compound heterozygous variants in SLC52A2 that were classified as pathogenic and a variant of uncertain significance. Bone marrow evaluation demonstrated megaloblastic changes. Notably, his anemia and neutropenia resolved after treatment with oral riboflavin, thus expanding the clinical phenotype of this disorder. We reiterate the importance of starting riboflavin supplementation in a young child who presents with macrocytic anemia and neurological features while awaiting biochemical and genetic work up. We detected multiple biochemical abnormalities with the help of untargeted metabolomics analysis associated with abnormal flavin adenine nucleotide function which normalized after treatment, emphasizing the reversible pathomechanisms involved in this disorder. The utility of untargeted metabolomics analysis to monitor the effects of riboflavin supplementation in RTD has not been previously reported.

Transitory response of a myelodysplastic syndrome with deletion of chromosome 5q to thalidomide. Report of one case

ABSTRACT Myelodysplastic syndrome with deletion of chromosome 5q (5q-syndrome) has a favorable prognosis and a low risk of transformation to acute myeloid leukemia, when treated with lenalidomide. Azacitidine leads to complete remission even as second-line therapy and in patients with clonal evolution. We report a 70 years old female without previous exposure to myelotoxic drugs, presenting with three weeks with fatigue and dyspnea. She had anemia with normal white blood cell and platelet count. Bone marrow biopsy showed 50% cellularity and the karyotype analysis revealed a (5) (q33q34) deletion in 22% of the metaphases. A diagnosis of 5q-syndrome with low risk calculated using the Revised International Prognostic Scoring System (IPSS-R), was made. Since lenalidomide was not affordable, thalidomide 100 mg/day was initiated, achieving transfusion independence for three years. Afterwards, she developed pancytopenia and a bone marrow biopsy showed erythroid and megakaryocyte dysplasia with a complex karyotype, which worsened prognosis (IPSS-R of five points). Therefore, azacitidine (by donation) was administered. She achieved complete remission with a normal karyotype and completed 12 cycles of treatment. Thereafter, she relapsed and received only supportive care for a year. She suffered an ischemic stroke and died two weeks later.

El síndrome mielodisplásico con deleción del cromosoma 5q (síndrome 5q) tiene un pronóstico favorable y riesgo bajo de transformación a leucemia aguda en pacientes que son tratados con lenalidomida (tratamiento estándar). El uso Azactidina tiene respuestas completas incluso como segunda línea de tratamiento en pacientes con evolución clonal. Presentamos una mujer de 71 años, sin exposición a mielotóxicos que debutó con un síndrome anémico. Se realizó biopsia de medula ósea que mostró celularidad del 50% y en el análisis citogenético se detectó una deleción del cromosoma 5 en 22% de las metafases analizadas, lo que llevó al diagnóstico de Síndrome 5q- de riesgo bajo de acuerdo con el puntaje IPSS-R (Revised International Prognostic Scoring System). Ya que no se pudo costear lenalidomida, se trató con talidomida (100 mg/día). Permaneció tres años sin requerir soporte transfusional. Posteriormente, presentó pancitopenia y en el nuevo aspirado de médula ósea se observó displasia de la serie roja y megacariocitos, con cariotipo complejo y peor pronóstico (IPSS-R 5 puntos). Se trató con 12 ciclos de azacitidina con lo que logró respuesta completa. Recayó 12 meses después y continuó manejo de soporte por un año. Finalmente falleció debido a un accidente vascular cerebral.

Prenatal diagnosis of concomitant distal 5q duplication and terminal 10q deletion in a fetus with intrauterine growth restriction, congenital diaphragmatic hernia and congenital heart defects.

OBJECTIVE: We present prenatal diagnosis of concomitant distal 5q duplication and terminal 10q deletion in a fetus with intrauterine growth restriction (IUGR), congenital diaphragmatic hernia (CDH) and congenital heart defects (CHD). CASE REPORT: A 34-year-old, gravida 4, para 2, woman was referred for amniocentesis at 21 weeks of gestation because of advanced maternal age and IUGR. There was no congenital malformation in the family. Amniocentesis revealed a derivative chromosome 10 with an additional maternal on the terminal region of 10q. Array comparative genomic hybridization (aCGH) analysis on the DNA extracted from the cultured amniocytes revealed a result of arr 5q31.3q35.5 (142, 548, 354-180,696,806) × 3.0, arr 10q26.3 (132, 932, 808-135,434,178) × 1.0 [GRCh37 (hg19)] with a 2.50-Mb deletion of 10q26.3 encompassing 19 [Online Mendelian Inheritance in Man (OMIM)] genes and a 38.15-Mb duplication of 5q31.3-q35.5 encompassing 195 OMIM genes including four CDH candidate genes of NDST1, ADAM19, NSD1 and MAML1. The mother was found to have a karyotype of 46,XX,t(5; 10) (q31.3; q26.3). Therefore, the fetal karyotype was 46,XX,der(10)t(5; 10)(q31.3; q26.3)mat. Prenatal ultrasound showed IUGR, right CDH, transposition of great artery, double outlet of right ventricle and right atrial isomerism. The pregnancy was terminated, and a malformed fetus was delivered with facial dysmorphism. CONCLUSION: Fetuses with concomitant distal 5q duplication and terminal 10q deletion may present IUGR, CDH and CHD on prenatal ultrasound.

Transitory response of a myelodysplastic syndrome with deletion of chromosome 5q to thalidomide. Report of one case.

Myelodysplastic syndrome with deletion of chromosome 5q (5q-syndrome) has a favorable prognosis and a low risk of transformation to acute myeloid leukemia, when treated with lenalidomide. Azacitidine leads to complete remission even as second-line therapy and in patients with clonal evolution. We report a 70 years old female without previous exposure to myelotoxic drugs, presenting with three weeks with fatigue and dyspnea. She had anemia with normal white blood cell and platelet count. Bone marrow biopsy showed 50% cellularity and the karyotype analysis revealed a (5) (q33q34) deletion in 22% of the metaphases. A diagnosis of 5q-syndrome with low risk calculated using the Revised International Prognostic Scoring System (IPSS-R), was made. Since lenalidomide was not affordable, thalidomide 100 mg/day was initiated, achieving transfusion independence for three years. Afterwards, she developed pancytopenia and a bone marrow biopsy showed erythroid and megakaryocyte dysplasia with a complex karyotype, which worsened prognosis (IPSS-R of five points). Therefore, azacitidine (by donation) was administered. She achieved complete remission with a normal karyotype and completed 12 cycles of treatment. Thereafter, she relapsed and received only supportive care for a year. She suffered an ischemic stroke and died two weeks later.

Deficiency and haploinsufficiency of histone macroH2A1.1 in mice recapitulate hematopoietic defects of human myelodysplastic syndrome.

BACKGROUND: Epigenetic regulation is important in hematopoiesis, but the involvement of histone variants is poorly understood. Myelodysplastic syndromes (MDS) are heterogeneous clonal hematopoietic stem cell (HSC) disorders characterized by ineffective hematopoiesis. MacroH2A1.1 is a histone H2A variant that negatively correlates with the self-renewal capacity of embryonic, adult, and cancer stem cells. MacroH2A1.1 is a target of the frequent U2AF1 S34F mutation in MDS. The role of macroH2A1.1 in hematopoiesis is unclear. RESULTS: MacroH2A1.1 mRNA levels are significantly decreased in patients with low-risk MDS presenting with chromosomal 5q deletion and myeloid cytopenias and tend to be decreased in MDS patients carrying the U2AF1 S34F mutation. Using an innovative mouse allele lacking the macroH2A1.1 alternatively spliced exon, we investigated whether macroH2A1.1 regulates HSC homeostasis and differentiation. The lack of macroH2A1.1 decreased while macroH2A1.1 haploinsufficiency increased HSC frequency upon irradiation. Moreover, bone marrow transplantation experiments showed that both deficiency and haploinsufficiency of macroH2A1.1 resulted in enhanced HSC differentiation along the myeloid lineage. Finally, RNA-sequencing analysis implicated macroH2A1.1-mediated regulation of ribosomal gene expression in HSC homeostasis. CONCLUSIONS: Together, our findings suggest a new epigenetic process contributing to hematopoiesis regulation. By combining clinical data with a discrete mutant mouse model and in vitro studies of human and mouse cells, we identify macroH2A1.1 as a key player in the cellular and molecular features of MDS. These data justify the exploration of macroH2A1.1 and associated proteins as therapeutic targets in hematological malignancies.

ZRSR2 mutation in a child with refractory macrocytic anemia and Down Syndrome.

Here we report a case of refractory macrocytic anemia with a spliceosomal point mutation involving the ZRSR2 gene in a child with Down syndrome (DS). Such mutations have been shown to cause refractory macrocytic anemia and myelodysplastic syndrome (MDS) in elderly individuals. We report the hematological indices of a child with DS and a ZRSR2 spliceosomal mutation. DS is known to produce macrocytic anemia but does not lead to transfusion dependence. In this case, the ZRSR2 mutation was the likely implicating factor for severe transfusion-dependent anemia in a child with DS. The clinical implication of a ZRSR2 mutation in a child with DS has not been previously described and warrants close surveillance to detect potential insidious transformation to MDS.

TASP1 mutation in a female with craniofacial anomalies, anterior segment dysgenesis, congenital immunodeficiency and macrocytic anemia.

BACKGROUND: Threonine Aspartase 1 (Taspase 1) is a highly conserved site-specific protease whose substrates are broad-acting nuclear transcription factors that govern diverse biological programs, such as organogenesis, oncogenesis, and tumor progression. To date, no single base pair mutations in Taspase 1 have been implicated in human disease. METHODS: A female infant with a new pattern of diagnostic abnormalities was identified, including severe craniofacial anomalies, anterior and posterior segment dysgenesis, immunodeficiency, and macrocytic anemia. Trio-based whole exome sequencing was performed to identify disease-causing variants. RESULTS: Whole exome sequencing revealed a normal female karyotype (46,XX) without increased regions of homozygosity. The proband was heterozygous for a de novo missense variant, c.1027G>A predicting p.(Val343Met), in the TASP1 gene (NM_017714.2). This variant has not been observed in population databases and is predicted to be deleterious. CONCLUSION: One human patient has been reported previously with a large TASP1 deletion and substantial evidence exists regarding the role of several known Taspase 1 substrates in human craniofacial and hematopoietic disorders. Moreover, Taspase 1 deficiency in mice results in craniofacial, ophthalmological and structural brain defects. Taken together, there exists substantial evidence to conclude that the TASP1 variant, p.(Val343Met), is pathogenic in this patient.

MDS with 5q deletion and rare cKIT positive mastocytosis: a diagnostic and therapeutic challenge.

A patient with a diagnosis of myelodysplastic syndrome (MDS) with isolated 5q deletion underwent repeat bone marrow biopsy to assess haematological response after 6 months of initial lenalidomide therapy. Subsequent bone marrow biopsies revealed persistent MDS with del(5q) in addition to a small atypical mast cell population with >25% of mast cells with spindle-shaped morphology and immunohistochemistry characteristics consistent with mastocytosis. Molecular testing on the bone marrow was positive for cKIT D816V and the patient was diagnosed with systemic mastocytosis (SM) with an associated haematological neoplasm. MDS with SM is well known to be associated; however, to the best of our knowledge, only one prior case report identifies MDS with del(5q) and associated cKIT D816V positive mastocytosis. While the exact clonal origin of both chromosomal aberrations is unclear, this case illustrates the therapeutic efficacy of lenalidomide in a patient with MDS with del(5q) and rarely associated cKIT positive SM.

Routes of Clonal Evolution into Complex Karyotypes in Myelodysplastic Syndrome Patients with 5q Deletion.

Myelodysplastic syndrome (MDS) can easily transform into acute myeloid leukemia (AML), a process which is often associated with clonal evolution and development of complex karyotypes. Deletion of 5q (del(5q)) is the most frequent aberration in complex karyotypes. This prompted us to analyze clonal evolution in MDS patients with del(5q). There were 1684 patients with low and intermediate-risk MDS and del(5q) with or without one additional cytogenetic abnormality, who were investigated cytogenetically in our department, involving standard karyotyping, fluorescence in situ hybridization (FISH) and multicolor FISH. We identified 134 patients (8%) with aspects of clonal evolution. There are two main routes of cytogenetic clonal evolution: a stepwise accumulation of cytogenetic events over time and a catastrophic event, which we defined as the occurrence of two or more aberrations present at the same time, leading to a sudden development of highly complex clones. Of the 134 patients, 61% underwent a stepwise accumulation of events whereas 39% displayed a catastrophic event. Patients with isolated del(5q) showed significantly more often a stepwise accumulation of events rather than a catastrophic event. The most frequent aberrations in the group of stepwise accumulation were trisomy 8 and trisomy 21 which were significantly more frequent in this group compared to the catastrophic event group. In the group with catastrophic events, del(7q)/-7 and del(17p)/-17 were the most common aberrations. A loss of 17p, containing the tumor suppressor gene TP53, was found significantly more frequent in this group compared to the group of stepwise accumulation. This leads to the assumption that the loss of TP53 is the driving force in patients with del(5q) who undergo a sudden catastrophic event and evolve into complex karyotypes.

KIBRA (WWC1) Is a Metastasis Suppressor Gene Affected by Chromosome 5q Loss in Triple-Negative Breast Cancer.

Triple-negative breast cancers (TNBCs) display a complex spectrum of mutations and chromosomal aberrations. Chromosome 5q (5q) loss is detected in up to 70% of TNBCs, but little is known regarding the genetic drivers associated with this event. Here, we show somatic deletion of a region syntenic with human 5q33.2-35.3 in a mouse model of TNBC. Mechanistically, we identify KIBRA as a major factor contributing to the effects of 5q loss on tumor growth and metastatic progression. Re-expression of KIBRA impairs metastasis in vivo and inhibits tumorsphere formation by TNBC cells in vitro. KIBRA functions co-operatively with the protein tyrosine phosphatase PTPN14 to trigger mechanotransduction-regulated signals that inhibit the nuclear localization of oncogenic transcriptional co-activators YAP/TAZ. Our results argue that the selective advantage produced by 5q loss involves reduced dosage of KIBRA, promoting oncogenic functioning of YAP/TAZ in TNBC.

Refractory macrocytic anemias in patients with clonal hematopoietic disorders and isolated mutations of the spliceosome gene ZRSR2.

Although mutations in RNA splicing genes occur frequently in patients with clonal cytopenias of unknown significance (CCUS) and myelodysplastic syndromes (MDS), very often additional common myeloid gene driver mutations are present at diagnosis. Thus, the clinical significance of isolated mutations in the most commonly mutated RNA splicing genes remains unknown. Here we report five unusual patients with an isolated mutation causing a loss of function of ZRSR2, a protein required for recognition of a functional 3' splice site. Two of the patients had a diagnosis of CCUS and three patients had an MDS disorder characterized by low risk features and absence of complex cytogenetic abnor-malities. Notably, all five cases were characterized predominantly by macrocytic anemia. In addition, one CCUS patient followed for more than 15 years with a transfusion dependent macrocytic anemia was found to have an inactivating ZRSR2 mutation with an allele frequency of >60%. We conclude that the common clinical features of patients with an isolated mutation of ZRSR2 are a macrocytic anemia without leukopenia, thrombocytopenia or an increase in marrow blast percentage. At least in some cases, the presence of an isolated ZRSR2 mutation can accompany a dominant hematopoietic clone with a low risk for transformation to frank dysplasia or acute leukemia.