Inherited platelet disorders (IPDs) are a heterogeneous group of rare entities caused by molecular divergence in genes relevant for platelet formation and function. A rational diagnostic approach is necessary to counsel and treat patients with IPDs. With the introduction of high-throughput sequencing at the beginning of this millennium, a more accurate diagnosis of IPDs has become available. We discuss advantages and limitations of genetic testing, technical issues, and ethical aspects. Additionally, we provide information on the clinical significance of different classes of variants and how they are correctly reported.Angeborene Thrombozytenstörungen (IPDs) sind eine heterogene Gruppe seltener Krankheiten, die durch molekulare Divergenz in Genen verursacht werden, die für die Bildung und Funktion von Blutplättchen relevant sind. Ein rationaler diagnostischer Ansatz ist notwendig, um Patienten mit IPDs zu beraten und zu behandeln. Mit der Einführung der Hochdurchsatz-Sequenzierung zu Beginn dieses Jahrtausends ist eine präzisere Diagnose von IPDs möglich geworden. Wir diskutieren Vorteile und Einschränkungen von genetischen Tests, technische Probleme und ethische Aspekte. Zusätzlich bieten wir Informationen über die klinische Bedeutung verschiedener Klassen von Varianten und wie sie korrekt gemeldet werden.
Erythrocytes undergo a well-defined switch from fetal to postnatal circulation, which is mainly reflected by the stage-specific expression of hemoglobin chains. Perinatal alterations in thrombopoiesis are poorly understood. We assessed the ontogenesis of platelet phenotype and function from early prematurity to adulthood. We recruited 64 subjects comprising 7 extremely preterm (27-31 weeks gestational age), 25 moderately preterm (32-36 weeks), 10 term neonates, 8 infants (<2 years), 5 children (2-13 years), and 9 adults (>13 years). Blood was withdrawn at up to 3 different time points in neonates (t1: 0-2, t2: 3-7, and t3: 8-14 days after birth). We found that the expression levels of the major surface receptors for fibrinogen, collagen, vWF, fibronectin, and laminin were reduced but correlated with decreased platelet size, indicating a normal surface density. Although CD62P and CD63 surface exposure upon stimulation with TRAP-6, ADP, or U46619 was unaltered or only slightly reduced in neonates, GPIIb/IIIa inside-out and outside-in activation was blunted but showed a continuous increase until adulthood, correlating with the expression of the GPIIb/IIIa regulating tetraspanin CD151. Platelet subpopulation analysis using automated clustering revealed that neonates presented with a CD63+/PAC-1- pattern, followed by a continuous increase in CD63+/PAC-1+ platelets until adulthood. Our findings revealed that the number of platelet-monocyte and platelet-neutrophil aggregates, but not platelet-lymphocyte aggregates, is increased in neonates and that neonatal aggregate formation depends in part on CD62P activation. Our PLatelets In Neonatal Infants Study (PLINIUS) provides several lines of evidence that the platelet phenotype and function evolve continuously from neonates to adulthood.
Introduction Total body irradiation (TBI) prior to hematopoietic stem cell transplantation (HSCT) is often the last therapeutic option for hemato-oncological diseases. Complications include bleeding due to prolonged thrombocytopenia but also thrombosis, such as veno-occlusive disease. The role of platelets in HSCT-related complications is yet ill defined.
Abstract During megakaryopoiesis, megakaryocytes (MKs) undergo cellular morphological changes with strong modification of membrane composition and lipid signaling. Here, we adopt a lipid-centric multiomics approach to create a quantitative map of the MK lipidome during maturation and proplatelet formation. Data reveal that MK differentiation is driven by an increased fatty acyl import and de novo lipid synthesis, resulting in an anionic membrane phenotype. Pharmacological perturbation of fatty acid import and phospholipid synthesis blocked membrane remodeling and directly reduced MK polyploidization and proplatelet formation, resulting in thrombocytopenia. The anionic lipid shift during megakaryopoiesis was paralleled by lipid-dependent relocalization of the scaffold protein CKIP-1 and recruitment of the kinase CK2α to the plasma membrane, which seems to be essential for sufficient platelet biogenesis. Overall, this study provides a framework to understand how the MK lipidome is altered during maturation and the effect of MK membrane lipid remodeling on MK kinase signaling involved in thrombopoiesis.
Thrombocytopenia absent radius (TAR) syndrome is a rare form of hereditary thrombocytopenia associated with a bilateral radial aplasia. TAR syndrome is genetically defined by the combination of a microdeletion on chromosome 1 which includes the gene RBM8A, and a single nucleotide polymorphism (SNP) in the second RBM8A allele. While most patients with TAR syndrome harbor a SNP in either the 5' UTR region or in intron 1 of RBM8A, further SNPs associated with TAR syndrome are still being identified. Here, we report on the current understanding of the genetic basis, diagnosis, and therapy of TAR syndrome and discuss patient self-empowerment by enabling networking and exchange between affected individuals and families.
