Inherited thrombocytopenias: an approach to diagnosis and management

The genomics of inherited bone marrow failure: from mechanism to the clinic

The inherited bone marrow failure syndromes (IBMFS) typically present with significant cytopenias in at least one haematopoietic cell lineage that may progress to pancytopenia, and are associated with increased risk of cancer. Although the clinical features of the IBMFS are often diagnostic, variable disease penetrance and expressivity may result in diagnostic dilemmas. The discovery of the genetic aetiology of the IBMFS has been greatly facilitated by next-generation sequencing methods. This has advanced understanding of the underlying biology of the IBMFS and been essential in improving clinical management and genetic counselling for affected patients. Herein we review the clinical features, underlying biology, and new genomic discoveries in the IBMFS, including Fanconi anaemia, dyskeratosis congenita, Diamond Blackfan anaemia, Shwachman Diamond syndrome and some disorders of the myeloid and megakaryocytic lineages.

Severe Clinical Course in a Patient with Congenital Amegakaryocytic Thrombocytopenia Due to a Missense Mutation of the c-MPL Gene

Congenital amegakaryocytic thrombocytopenia (CAMT) generally begins at birth with severe thrombocytopenia and progresses to pancytopenia. It is caused by mutations in the thrombopoietin receptor gene, the myeloproliferative leukemia virus oncogene (c-MPL). The association between CAMT and c-MPL mutation type has been reported in the literature. Patients with CAMT have been categorized according to their clinical symptoms caused by different mutations. Missense mutations of c-MPL have been classified as type II and these patients have delayed onset of bone marrow failure compared to type I patients. Here we present a girl with severe clinical course of CAMT II having a missense mutation in exon 4 of the c-MPL gene who was admitted to our hospital with intracranial hemorrhage during the newborn period.

Assessment of Platelet Function in Whole Blood by Flow Cytometry

Evaluation of platelet function is important for understanding the physiology of hemostasis and thrombosis and is utilized in clinical practice to diagnose inherited and acquired platelet bleeding disorders. Flow cytometry is a powerful tool for rapid evaluation of multiple functional properties of large number of platelets in whole blood and offers many advantages over other traditional methods. Attention to pre-analytical factors is required to ensure biologically valid and robust results.

Quantitation of bleeding symptoms in a national registry of patients with inherited platelet disorders

BACKGROUND

Inherited platelet deficiency and/or dysfunction may be more common in the general population than has previously been appreciated. In 2013 the Israeli Inherited Platelet Disorder (IPD) Registry was established.

METHODS

Clinical and laboratory data were collected to pre-specified registration forms. The study protocol was approved by the local hospital ethics committees.

RESULTS

To date we have included in the registry 89 patients (male 52%) from 79 families. Most patients (74%) have a not-yet specified inherited thrombocytopenia (n=39) or non-specific platelet function disorder (n=27). Full clinical data were available for 81 (91%) patients. The median (range) age at presentation and time of follow-up were 1.8years (1day-17.8years) and 4.7 (0-26) years, respectively. The Pediatric Bleeding Questionnaire was available for 78patients; abnormal bleeding score (≥2) was recorded in 47 (52.8%, 95% CI 42%-63.5%) patients and was less frequent in patients followed for isolated thrombocytopenia. Abnormal score was associated with a longer time of follow-up, OR 1.19 (95% CI 1.04-1.36).

CONCLUSION

Long term follow-up of patients with IPDs is important as bleeding risks may increase with time. We expect that clinical and laboratory information of patients/families with IPDs gathered in a systemic format will allow for better diagnosis and treatment of these patients.

Toxicological implications and laxative potential of ethanol root extract of Morella serrata in loperamide-induced constipated Wistar rats

CONTEXT

Morella serrata L. (Myricaceae) is commonly used in South Africa to treat several diseases including constipation.

OBJECTIVES

This study investigated toxicological implications and laxative potential of the ethanol root extract of the plant.

MATERIALS AND METHODS

While normal control animals were placed on sterile placebo, the loperamide-constipated rats were treated with the extract at 75, 150 and 300 mg/kg doses for 7 days, and their feeding patterns and faecal properties were monitored. Gastrointestinal transit ratio and the toxicity profile of the tested doses were thereafter evaluated.

RESULTS

The significantly increased faecal volume (192.08%), feed (63.63%), water intake (55.97%) and improved intestinal motility (95.05%) in the constipated rats following treatment with the extract (at 300 mg/kg) suggested laxative potential of the extract. The 1.5-2.0-fold normalization of the platelets, erythrocytes and leukocytes counts in the extract-treated constipated rats suggests its non-haematotoxic tendency. Furthermore, the extract (at the highest investigated dose) reversed the attenuation in the concentrations of the electrolytes (0.5-2-fold), total protein (62.12%) and albumin (55.88%) in the constipated animals as well as attenuated activities of hepatic enzymes (0.5-3.0-fold) and levels of urea (126.67%), creatinine (40.32%), cholesterol (3-fold) and triglycerides (9-fold). These further support its non-toxic and therapeutic attributes against constipation.

CONCLUSION

Overall, the effect exhibited by M. serrata in this study competed well with Senokot (standard drug) and proved that it may be relatively safe and with excellent laxative potential, thus, supporting its pharmacological applications in South Africa.

Acute and Subacute Toxicological Evaluation of the Aerial Extract of Monsonia angustifolia E. Mey. ex. A. Rich in Wistar Rats

The acute and subacute toxicity profile of the aerial extract of Monsonia angustifolia in Wistar rats was evaluated. The Organization for Economic Cooperation and Development (OECD) 420 guideline was adopted in the acute toxicity testing with a single oral dose of 5000 mg/kg (b.w.). For the 28-day daily oral dosing, the extract was administered at 75, 150, and 300 mg/kg b.w.; 1% ethanol in sterile distilled water was used as control. Clinical toxicity signs were subsequently evaluated. At a single dose of 5000 mg/kg b.w. the extract elicited no treatment-related signs of toxicity in the animals during the 14 days of experimental period. In the subacute toxicity, there was no significant difference in hematological, renal, and liver function indices. However, dose-dependent significant increases were observed on the plasma concentrations of white blood cell and platelet counts of the treated animals compared to the control group. While cage observations revealed no treatment-facilitated signs of toxicity, histopathological examinations of the kidneys and liver also showed no obvious lesions and morphological changes. These results suggest that the extract may be labelled and classified as safe and practically nontoxic within the doses and period of investigation in this study.

Toxicological evaluations of Stigma maydis (corn silk) aqueous extract on hematological and lipid parameters in Wistar rats

Despite the acclaimed phytotherapeutic attributes of Stigma maydis in folkloric medicine, there is paucity of information on its toxicity profile on hematological and lipid parameters. The toxicological effect of aqueous extract of corn silk at 100, 200 and 400 mg/kg body weight on hematological indices in Wistar rats were evaluated progressively at 24 h after 1, 7, 14, 21 and 28 days. Lipid parameters were also analyzed at the end of the experimental period. We observed that the extract did not exhibit any significant (p > 0.05) effect on red blood cells, hematocrit, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and mean platelet volume at all the tested doses. The study however showed a significant increase in the serum levels of white blood cell, platelet, lymphocytes, high-density lipoprotein cholesterol; as well as feeding pattern in the animals, while the concentrations of total cholesterol, low-density lipoprotein cholesterol, and artherogenic index value were significantly lowered. These findings are suggestive of non-hematotoxic potential of the extract. Overall, the effect exhibited by corn silk extract in this study proved that, it is unlikely to be hematotoxic and could be a good candidature in the management of coronary heart diseases if consumed at the doses investigated.

Sp1/Sp3 transcription factors regulate hallmarks of megakaryocyte maturation and platelet formation and function

Sp1 and Sp3 belong to the specificity proteins (Sp)/Krüppel-like transcription factor family. They are closely related, ubiquitously expressed, and recognize G-rich DNA motifs. They are thought to regulate generic processes such as cell-cycle and growth control, metabolic pathways, and apoptosis. Ablation of Sp1 or Sp3 in mice is lethal, and combined haploinsufficiency results in hematopoietic defects during the fetal stages. Here, we show that in adult mice, conditional pan-hematopoietic (Mx1-Cre) ablation of either Sp1 or Sp3 has minimal impact on hematopoiesis, whereas the simultaneous loss of Sp1 and Sp3 results in severe macrothrombocytopenia. This occurs in a cell-autonomous manner as shown by megakaryocyte-specific (Pf4-Cre) double-knockout mice. We employed flow cytometry, cell culture, and electron microscopy and show that although megakaryocyte numbers are normal in bone marrow and spleen, they display a less compact demarcation membrane system and a striking inability to form proplatelets. Through megakaryocyte transcriptomics and platelet proteomics, we identified several cytoskeleton-related proteins and downstream effector kinases, including Mylk, that were downregulated upon Sp1/Sp3 depletion, providing an explanation for the observed defects in megakaryopoiesis. Supporting this notion, selective Mylk inhibition by ML7 affected proplatelet formation and stabilization and resulted in defective ITAM receptor-mediated platelet aggregation.

von Willebrand disease and platelet disorders

The diagnosis and management of bleeding disorders is made difficult by the complexity and variety of disorders, clinical symptoms and bleeding type and severity. von Willebrand disease (VWD) and platelet disorders are disorders of primary haemostasis and together represent the most common inherited bleeding disorders. In this article, we describe the diagnosis of VWD and platelet disorders and the treatment options for VWD.

What can proteomics tell us about platelets?

More than 130 years ago, it was recognized that platelets are key mediators of hemostasis. Nowadays, it is established that platelets participate in additional physiological processes and contribute to the genesis and progression of cardiovascular diseases. Recent data indicate that the platelet proteome, defined as the complete set of expressed proteins, comprises >5000 proteins and is highly similar between different healthy individuals. Owing to their anucleate nature, platelets have limited protein synthesis. By implication, in patients experiencing platelet disorders, platelet (dys)function is almost completely attributable to alterations in protein expression and dynamic differences in post-translational modifications. Modern platelet proteomics approaches can reveal (1) quantitative changes in the abundance of thousands of proteins, (2) post-translational modifications, (3) protein-protein interactions, and (4) protein localization, while requiring only small blood donations in the range of a few milliliters. Consequently, platelet proteomics will represent an invaluable tool for characterizing the fundamental processes that affect platelet homeostasis and thus determine the roles of platelets in health and disease. In this article we provide a critical overview on the achievements, the current possibilities, and the future perspectives of platelet proteomics to study patients experiencing cardiovascular, inflammatory, and bleeding disorders.

Inherited, congenital and acquired disorders by hemostasis (vascular, platelet & plasmatic phases) with repercussions in the therapeutic oral sphere

The hemostasis alterations, either congenital or hereditary origin, and acquired, are circumstances that hinder oral care to patients who suffer them and also generates in the professional who has to attend, high stress. Bleeding control once established and dental treatment planning, both in the aspect of preparation, as the realization of the odonto-stomatological therapeutic, has suffered updates that do need to remember certain aspects of the care of these patients. But we must not forget that the hematologist or internist who controls the patient's medical condition, is a cornerstone for the planning and implementation of treatment plans. We must also remember that, in certain circumstances, treatment should be performed in a hospital setting. In this review, we aim to provide the odonto-stomatologist guidance on how to address the problem and provide simple and updated guidelines to apply in the treatment of these people.

Lessons in platelet production from inherited thrombocytopenias

Our knowledge of the cellular and molecular mechanisms of platelet production has greatly expanded in recent years due to the opportunity to culture in vitro megakaryocytes and to create transgenic animals with specific genetic defects that interfere with platelet biogenesis. However, in vitro models do not reproduce the complexity of the bone marrow microenvironment where megakaryopoiesis takes place, and experience shows that what is seen in animals does not always happen in humans. So, these experimental models tell us what might happen in humans, but does not assure us that these events really occur. In contrast, inherited thrombocytopenias offer the unique opportunity to verify in humans the actual effects of abnormalities in specific molecules on platelet production. There are currently 20 genes whose defects are known to result in thrombocytopenia and, on this basis, this review tries to outline a model of megakaryopoiesis based on firm evidence. Inherited thrombocytopenias have not yet yielded all the information they can provide, because nearly half of patients have forms that do not fit with any known disorder. So, further investigation of inherited thrombocytopenias will advance not only the knowledge of human illnesses, but also our understanding of human platelet production.