Morphologic and GATA1 sequencing analysis of hematopoiesis in fetuses with trisomy 21

Prenatal diagnosis of Down syndrome combined with transient abnormal myelopoiesis in foetuses with a GATA1 gene variant: two case reports

BACKGROUND

Down syndrome myeloid hyperplasia includes transient abnormal myelopoiesis (TAM) and the myeloid leukemia associated with Down syndrome (ML-DS). The mutation of GATA1 gene is essential in the development of Down syndrome combined with TAM or ML-DS. Some patients with TAM are asymptomatic and may also present with severe manifestations such as hepatosplenomegaly and hydrops.

CASE PRESENTATION

We report two cases of prenatally diagnosed TAM. One case was a rare placental low percentage 21 trisomy mosiacism, resulting in the occurrence of a false negative NIPT. The final diagnosis was made at 36 weeks of gestation when ultrasound revealed significant enlargement of the foetal liver and spleen and an enlarged heart; the foetus eventually died in utero. We detected a placenta with a low percentage (5-8%) of trisomy 21 mosiacism by Copy Number Variation Sequencing (CNV-seq) and Fluorescence in situ hybridization (FISH). In another case, foetal oedema was detected by ultrasound at 31 weeks of gestation. Two foetuses were diagnosed with Down syndrome by chromosomal microarray analysis via umbilical vein puncture and had significantly elevated cord blood leucocyte counts with large numbers of blasts. The GATA1 Sanger sequencing results suggested the presence of a [NM_002049.4(GATA1):c.220G > A (p. Val74Ile)] hemizygous variant and a [NM_002049.4(GATA1):c.49dupC(p. Gln17ProfsTer23)] hemizygous variant of the GATA1 gene in two cases.

CONCLUSION

It seems highly likely that these two identified mutations are the genetic cause of prenatal TAM in foetuses with Down syndrome.

Hematologic Neoplasms Associated with Down Syndrome: Cellular and Molecular Heterogeneity of the Diseases

The molecular basis of Down syndrome (DS) predisposition to leukemia is not fully understood but involves various factors such as chromosomal abnormalities, oncogenic mutations, epigenetic alterations, and changes in selection dynamics. Myeloid leukemia associated with DS (ML-DS) is preceded by a preleukemic phase called transient abnormal myelopoiesis driven by GATA1 gene mutations and progresses to ML-DS via additional mutations in cohesin genes, CTCF, RAS, or JAK/STAT pathway genes. DS-related ALL (ALL-DS) differs from non-DS ALL in terms of cytogenetic subgroups and genetic driver events, and the aberrant expression of CRLF2, JAK2 mutations, and RAS pathway-activating mutations are frequent in ALL-DS. Recent advancements in single-cell multi-omics technologies have provided unprecedented insights into the cellular and molecular heterogeneity of DS-associated hematologic neoplasms. Single-cell RNA sequencing and digital spatial profiling enable the identification of rare cell subpopulations, characterization of clonal evolution dynamics, and exploration of the tumor microenvironment's role. These approaches may help identify new druggable targets and tailor therapeutic interventions based on distinct molecular profiles, ultimately improving patient outcomes with the potential to guide personalized medicine approaches and the development of targeted therapies.

Mapping the cellular origin and early evolution of leukemia in Down syndrome

Children with Down syndrome have a 150-fold increased risk of developing myeloid leukemia, but the mechanism of predisposition is unclear. Because Down syndrome leukemogenesis initiates during fetal development, we characterized the cellular and developmental context of preleukemic initiation and leukemic progression using gene editing in human disomic and trisomic fetal hematopoietic cells and xenotransplantation. GATA binding protein 1 (GATA1) mutations caused transient preleukemia when introduced into trisomy 21 long-term hematopoietic stem cells, where a subset of chromosome 21 microRNAs affected predisposition to preleukemia. By contrast, progression to leukemia was independent of trisomy 21 and originated in various stem and progenitor cells through additional mutations in cohesin genes. CD117+/KIT proto-oncogene (KIT) cells mediated the propagation of preleukemia and leukemia, and KIT inhibition targeted preleukemic stem cells.

Transient Myeloproliferative Disorder: An Update for Neonatal Nurses

Down syndrome (DS) is a well-known genetic disorder that affects 700-1,000 infants per year. One particular comorbidity of DS is transient myeloproliferative disorder (TMD), a disease characterized by leukocytosis with elevated blast counts. Approximately 10 percent of DS infants develop TMD, which usually manifests during the first week of life and can lead to an extended hospitalization in a NICU. In addition to hallmark hematologic findings, other manifestations include jaundice, conjugated hyperbilirubinemia, hepatomegaly, and pericardial or pleural effusions. TMD generally resolves spontaneously in the first three months of life with the provision of timely medical management; however, survivors are at increased risk of developing acute myeloid leukemia (AML). Neonatal nurses need to have knowledge of this disorder to facilitate screening of DS infants and optimize family education and coordination of care.

GATA family transcriptional factors: emerging suspects in hematologic disorders

GATA transcription factors are zinc finger DNA binding proteins that regulate transcription during development and cell differentiation. The three important GATA transcription factors GATA1, GATA2 and GATA3 play essential roles in the development and maintenance of hematopoietic systems. GATA1 is required for the erythroid and megakaryocytic commitment during hematopoiesis. GATA2 is crucial for the proliferation and survival of early hematopoietic cells, and is also involved in lineage specific transcriptional regulation as the dynamic partner of GATA1. GATA3 plays an essential role in T lymphoid cell development and immune regulation. As a result, mutations in genes encoding the GATA transcription factors or alteration in the protein expression level or their function have been linked to a variety of human hematologic disorders. In this review, we summarized the current knowledge regarding the disrupted biologic function of GATA in various hematologic disorders.

The secret life of a megakaryocyte: emerging roles in bone marrow homeostasis control

Megakaryocytes are rare cells found in the bone marrow, responsible for the everyday production and release of millions of platelets into the bloodstream. Since the discovery and cloning, in 1994, of their principal humoral factor, thrombopoietin, and its receptor c-Mpl, many efforts have been directed to define the mechanisms underlying an efficient platelet production. However, more recently different studies have pointed out new roles for megakaryocytes as regulators of bone marrow homeostasis and physiology. In this review we discuss the interaction and the reciprocal regulation of megakaryocytes with the different cellular and extracellular components of the bone marrow environment. Finally, we provide evidence that these processes may concur to the reconstitution of the bone marrow environment after injury and their deregulation may lead to the development of a series of inherited or acquired pathologies.

Congenital GATA1-mutated myeloproliferative disorder in trisomy 21 complicated by placental fetal thrombotic vasculopathy

Congenital myeloproliferative disorders and transient leukemic disorders have been described in the perinatal period in infants with trisomy 21 (Down syndrome). We report a novel case of a neonate with trisomy 21 with GATA1-mutated congenital myeloproliferative disorder complicated by placental fetal thrombotic vasculopathy featuring chorionic vessel leukemic thrombi, fetal circulation vascular injuries, and large aggregates of avascular villi. These thrombotic and vasculopathic changes within the placenta are likely a reflection of the hypercoagulable state caused by the myeloproliferative disorder. Placental fetal thrombotic vasculopathy is associated with adverse outcomes for the infant, and should be documented during formal pathological examination of the placenta.