Myeloid proliferation without GATA1 mutations in a fetus with Down syndrome presenting in utero as a pericardial effusion

Acute Megakaryocytic Leukemia

Acute megakaryoblastic leukemia (AMKL) is a rare malignancy affecting megakaryocytes, platelet-producing cells that reside in the bone marrow. Children with Down syndrome (DS) are particularly prone to developing the disease and have a different age of onset, distinct genetic mutations, and better prognosis as compared with individuals without DS who develop the disease. Here, we discuss the contributions of chromosome 21 genes and other genetic mutations to AMKL, the clinical features of the disease, and the differing features of DS- and non-DS-AMKL. Further studies elucidating the role of chromosome 21 genes in this disease may aid our understanding of how they function in other types of leukemia, in which they are frequently mutated or differentially expressed. Although researchers have made many insights into understanding AMKL, much more remains to be learned about its underlying molecular mechanisms.

Fetal/Neonatal Pericardial Effusion in Down's Syndrome: Case Report and Review of Literature

We report a preterm (35 ^4/7 weeks) male neonate with Down's syndrome (DS) diagnosed with isolated pericardial effusion (PE) at 20 weeks of gestation. He was born by precipitous delivery, needed no resuscitation and presented within first 24 hours of life with respiratory distress, anemia due to feto-maternal bleed, hypotension, hepatomegaly, and coagulopathy. Postnatal echocardiography confirmed a 5 mm rim of PE without tamponade, normal cardiac structure, and function. He was stabilized with ventilation, packed red cell, fresh frozen plasma, inotropes (dopamine, dobutamine, and adrenaline), and steroid (hydrocortisone). Subsequent evaluation confirmed hypothyroidism, transient myeloproliferative disorder (TMD), hepatic failure due to fibrosis/cirrhosis with portal hypertension, and steroid sensitive hypotension on two occasions possibly due to adrenal insufficiency. PE completely resolved over 2 weeks. In view of progressively worsening liver failure with ascites and portal hypertension, the family opted for palliation. Literature review has been discussed regarding perinatal onset of PE in DS.

A dysmorphic newborn with petechiae and a 'Big Heart'

A male fetus was noted to have an isolated pericardial effusion. At birth, he had dysmorphic features of Down syndrome and extensive petechiae. He was diagnosed to have transient myeloproliferative disorder. The large pericardial effusion and TMD spontaneously resolved. At 4 years of age, he was diagnosed with acute megakaryoblastic leukaemia, underwent chemotherapy and achieved complete remission.

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

Trisomy 21 alters fetal liver hematopoiesis and, in combination with somatic globin transcription factor 1 (GATA1) mutations, leads to development of transient myeloproliferative disease in newborns. However, little is known about the morphological hematopoietic changes caused by trisomy 21 in the fetus, and to date, the exact onset of GATA1 mutations remains uncertain. Therefore, we analyzed fetal liver hematopoiesis from second trimester pregnancies in trisomy 21 and screened for GATA1 mutations. We examined 57 formalin-fixed and paraffin-embedded fetal liver specimens (49 harboring trisomy 21 and 8 controls) by immunohistochemistry for CD34, CD61, factor VIII, and glycophorin A. GATA1 exon 2 was sequenced in fetal livers and corresponding nonhematologic tissue. Cell counts of megakaryocytes (P = .022), megakaryocytic precursors (P = .021), and erythroid precursors were higher in trisomy 21 cases. CD34-positive hematopoietic blasts showed no statistically significant differences. No mutation was detected by GATA1 exon 2 sequencing in fetal livers from 12 to 25 weeks of gestation. Our results suggest that GATA1 exon 2 mutations occur late in trisomy 21 fetal hematopoiesis. However, trisomy 21 alone provides a proliferative stimulus of fetal megakaryopoiesis and erythropoiesis. CD34-positive precursor cells are not increased in trisomy 21 fetal livers.

Tumorigenesis in Down's syndrome: big lessons from a small chromosome

If assessed by a number of criteria for cancer predisposition, Down's syndrome (DS) should be an overwhelmingly cancer-prone condition. Although childhood leukaemias occur more frequently in DS, paradoxically, individuals with DS have a markedly lower incidence of most solid tumours. Understanding the mechanisms that are capable of overcoming such odds could potentially open new routes for cancer prevention and therapy. In this Opinion article, we discuss recent reports that suggest unique and only partially understood mechanisms behind this paradox, including tumour repression, anti-angiogenic effects and stem cell ageing and availability.