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Haematological Disease
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
These are extremely rare. Affected individuals have a lifelong bleeding tendency, which can pose difficulties in surgery and childbirth. Glanzmann's thrombocythaemia: autosomal recessive inherited deficiency of platelet fibrinogen receptorsBernard–Soulier disease: autosomal recessive inherited deficiency of platelet vWF receptorsPlatelet storage pool deficiency and transduction disorders: a larger group of inherited mild bleeding disorders in which platelet activation mechanisms are disturbed
The Beige (bg) Mutation, Chromosome 13
Published in John P. Sundberg, Handbook of Mouse Mutations with Skin and Hair Abnormalities, 2020
A variety of immunological deficiencies or abnormalities associated with the granular defects are well known for the beige mutation. These include defective and reduced bactericidal activity of granulocytes,12 severe deficiency of natural killer (NK) cells,13 and a defective cytotoxic T cell and antibody response to allogeneic tumor cells.14,15 A variety of lysosomal enzymes are decreased in neutrophils.16–18 Heterozygotes also have a platelet storage pool deficiency and serotonin deficiency within the platelets resulting in prolonged bleeding times.19,20 This can be corrected by bone marrow grafts from normal mice.21
Approach to hypopigmentation
Published in Electra Nicolaidou, Clio Dessinioti, Andreas D. Katsambas, Hypopigmentation, 2019
Clio Dessinioti, Andreas D. Katsambas
Hermansky-Pudlak syndrome: Rare, albinism with extrapigmentary disorders. Platelet storage pool deficiency resulting in bleeding diathesis, ceroid storage disease resulting in pulmonary fibrosis, kidney failure, granulomatous colitis.14
Coexistence of Hermansky-Pudlak syndrome and JAK2V617F-positive essential thrombocythemia
Published in Ultrastructural Pathology, 2019
Tugce Eskazan, Salime Pelin Erturkuner, Basak Isildar, Ahmet Emre Eskazan, Muhlis Cem Ar, Kadri Atay, Zafer Baslar, Mustafa Tasyurekli
Ex vivo analyses of ET revealed that existing high shear stress in the microvasculature, causes platelets to be spontaneously activated, secreting their products to form aggregates mediated by vWF which temporarily obstruct the microcirculation, but then deaggregate, and recirculate as exhausted defective platelets with secondary storage pool disease.16 In our patient, there was an HPS-associated primary platelet storage pool deficiency and most probably a second storage-pool disease as a result of ET.
Structure and function of the open canalicular system – the platelet’s specialized internal membrane network
Published in Platelets, 2018
Maria V. Selvadurai, Justin R. Hamilton
Limited information on OCS function can be gleaned from human conditions. There are a number of clinical syndromes where abnormalities in the OCS have been documented, including some conditions that involve bleeding or thrombotic sequelae. However, platelets from patients with each of these conditions have a number of other structural abnormalities, making it difficult to ascertain the specific contribution of the OCS defect, if any, to any altered platelet function. For example, a dilated, hypertrophic OCS is seen in platelets from patients with Bernard–Soulier syndrome (BSS; Figure 3). BSS is the result of an abnormality in the gene encoding the GPIb (or occasionally GPIX) component of the GPIb/IX/V receptor complex and manifests as a bleeding disorder (46). More than 100 BSS-causing mutations in these genes have been identified, which impair either the expression of the receptor complex at the plasma membrane or the ability of the receptor to interact with von Willebrand factor (47). Yet, in addition to the OCS defect, platelets from these patients are also giant, exhibit disorganized microtubules, and have sparse or even absent granulation. A similar phenotype is observed in platelets from patients with MYH9-related disorders (e.g. May–Hegglin anomaly, Epstein syndrome, Fechtner syndrome). As with BSS, platelets from these patients exhibit not only a dilated and hypertrophic OCS, but also a pronounced macrothrombocytopenia and marked agranularity (17,48,49) (Figure 3). Intriguingly, Budd–Chiari syndrome, a rare prothrombotic condition characterized by hepatic vein or inferior vena cava thrombosis (50), also results in platelets with dilation and hypertrophy of the OCS (51). Yet, again, multiple other platelet ultrastructural defects are observed, including a general lack of organelle content (Figure 3). Finally, abnormal linkage of storage granules to the OCS has been implicated in alpha–delta platelet storage pool deficiency. In an ultrastructural study of multiple familial cases of the disease, it was found that alpha and dense granules were replaced by empty vacuolar structures in platelets from these patients, and that many of these vacuoles were connected to the OCS, suggesting that extraneous connections between the granules and OCS result in the loss of granule contents to the cell exterior in the absence of platelet activation (52). Given the lack of examples of a specific OCS defect in human platelets, direct evidence of OCS function has been limited to emerging information derived from genetically modified mouse models.