Tetrasomy 21 as a sole acquired abnormality without GATA1 gene mutation in pediatric acute megakaryoblastic leukemia: A case report and review of the literature

Analysis 33 patients of non-DS-AMKL with or without acquired trisomy 21 from multiple centers and compared to 118 AML patients

BACKGROUND

Acute megakaryoblastic leukemia (AMKL) without Down syndrome (non-DS-AMKL) usually a worse outcome than DS-AMKL. Acquired trisomy 21(+21) was one of the most common cytogenetic abnormalities in non-DS-AMKL. Knowledge of the difference in the clinical characteristics and prognosis between non-DS-AMKL with +21 and those without +21 is limited.

OBJECTIVE

Verify the clinical characteristics and prognosis of non-DS-AMKL with +21.

METHOD

We retrospectively analyzed 33 non-DS-AMKL pediatric patients and 118 other types of AML, along with their clinical manifestations, laboratory data, and treatment response.

RESULTS

Compared with AMKL without +21, AMKL with +21 has a lower platelet count (44.04 ± 5.01G/L) at onset (P > 0.05). Differences in remission rates between AMKL and other types of AML were not significant. Acquired trisomy 8 in AMKL was negatively correlated with the long-term OS rate (P < 0.05), while +21 may not be an impact factor. Compared with the other types of AML, AMKL has a younger onset age (P < 0.05), with a mean of 22.27 months. Anemia, hemorrhage, lymph node enlargement, lower white blood cell, and complex karyotype were more common in AMKL (P < 0.05). AMKL has a longer time interval between onset to diagnosis (53.61 ± 71.15 days) (P < 0.05), and patients with a diagnosis delay ≥3 months always presented as thrombocytopenia or pancytopenia initially.

CONCLUSIONS

Due to high heterogeneity, high misdiagnosis rate, and myelofibrosis, parts of AMKL may take a long time to be diagnosed, requiring repeated bone marrow punctures. Complex karyotype was common in AMKL. +21 may not be a promising indicator of a poor prognosis.

Clinical genomics and contextualizing genome variation in the diagnostic laboratory

INTRODUCTION

The human genome contains the instructions for the development and biological homeostasis of the human organism and the genetic transmission of traits. Genome variation in human populations is the basis of evolution; individual or personal genomes vary tremendously, making each of us truly unique.

AREAS COVERED

Assaying this individual variation using genomic technologies has many applications in clinical medicine, from elucidating the biology of disease to designing strategies to ameliorate perturbations from homeostasis. Detecting pathogenic rare variation in a genome may provide a molecular diagnosis that can be informative for patient management and family healthcare.

EXPERT OPINION

Despite the increasing clinical use of unbiased genomic testing, including chromosome microarray analysis (CMA) with array comparative genomic hybridization (aCGH) or SNP arrays, clinical exome sequencing (cES), and whole-genome sequencing (WGS), to survey genome-wide for molecular aberrations, clinical acumen paired with an understanding of the limitations of each testing type will be needed to achieve molecular diagnoses. Potential opportunities for improving case solved rates, functionally annotating the majority of genes in the human genome, and further understanding genetic contributions to disease will empower clinical genomics and the precision medicine initiative.

Mosaic Trisomy 21 and Trisomy 14 as Acquired Cytogenetic Abnormalities without GATA1 Mutation in A Pediatric Non-Down Syndrome Acute Megakaryoblastic Leukemia

One case of acute megakaryoblastic leukemia (AMKL) with trisomy 21, trisomy 14 and unmutated GATA1 gene in a phenotypically normal girl was reported. The patient experienced transient myelodysplasia before the onset of AMKL. The bone marrow blasts manifested typical morphology of megakaryoblast both by the May-Giemsa staining and under the electronic microscopy. Leukemic cells were positive for CD13, CD33, CD117, CD56, CD38, CD41 and CD61 in flow cytometry analysis. Cytogenetic study showed karyotype of 48, XX, +14, +21 in 40% metaphases. Known mutations of GATA1 gene in Down syndrome or acquired trisomy 21 were not detected in this case.

Transient myeloproliferative disorder and GATA1 mutation in neonates with and without Down syndrome

OBJECTIVE

To report clinical experiences and cytogenetic findings of transient myeloproliferative disorder (TMD) in neonates with and without Down syndrome (DS).

METHODS

GATA1 gene was screened in DNA samples from neonates presenting with TMD during their leukemic and remission status.

RESULTS

Six neonates (2 phenotypically normal and 4 DS) born in the past 6 years had presented with TMD; all had trisomy 21 during leukemic status. Two DS infants died during early infancy, one of hepatic failure and one of cardiac complication. One non-DS infant evolved into myelodysplastic syndrome (MDS) and acute leukemia since 14 months old. Three other patients have not developed true leukemia after follow-up of 8, 9, and 70 months, respectively. The authors detected mutations within exon 2 of GATA1 gene in 3 DS and 2 non-DS infants. All these mutations disappeared after remission of TMD, but an identical mutation was detected in one non-DS patient when evolving into MDS. Trisomy 21 was confined to leukemic clone in non-DS patients.

CONCLUSIONS

TMD should be considered in case of congenital leukemia with megakaryoblastic features and accompanied by trisomy 21 and GATA1 mutation. Both DS and non-DS patients will possibly develop true leukemia within few years.

A case of childhood acute myeloid leukemia AML (M5) with a neocentric chromosome neo(1)(qter-->q23 approximately 24::q23 approximately 24-->q43-->neo-->q43-->qter) and tetrasomy of chromosomes 8 and 21

Hyperdiploidy is rarely observed in childhood acute myeloid leukemia (AML). Described here is the case of a 2(1/2)-year-old girl with AML-M5 and 51 chromosomes characterized by double tetrasomy of chromosomes 8 and 21 and also a neocentric derivative chromosome neo(1)(qter-->q23 approximately 24::q23 approximately 24-->q43-->neo-->q43-->qter). Little is known about the prognostic significance of these chromosomal abnormalities in childhood AML. In the actual case, complete remission was achieved after chemotherapy, which continued for 7 months. No acquired neocentric chromosome 1 has been described previously, even though neocentromere formation has been reported for other chromosomes in neoplasms.