A Morphometric Analysis of Platelet Dense Granules of Patients with Unexplained Bleeding: A New Entity of Delta-Microgranular Storage Pool Deficiency

Abstract

One thousand and eighty patients, having prolonged bleeding times, frequent epistaxis, menorrhagia or easy bruising or other bleeding manifestations, and excluding those with von Willebrand’s disease, were evaluated for platelet dense granule deficiency. The mean diameter of platelet dense granules was determined for all patients using image analysis. Four hundred and ninety-nine had “classic” dense (delta) granule storage pool deficiency (δ-SPD). Five hundred and eighty-one individuals (53.8%) were found to have a normal mean number of dense granules, but for some of these patients, the dense granules were smaller than for the controls. Of the patients having a normal number of dense granules, 165 (28.4%) were found to have significantly smaller granules than the platelets obtained from the control subjects. Their average granule diameter was 123.35 ± 0.86 nm, that is more than three standard deviations below the mean of the control data. Total δ-granule storage pool volumes (TDGV)/platelet were calculated using these measurements. Individuals with δ-SPD had half the number of granules (2.25 ± 0.04 DG/PL) and storage pool volume (3.88 ± 1.06 × 106 nm3) when compared to our control data (4.64 ± 0.11 DG/PL; 10.79 × 106 nm3 ± 0.42). Individuals having a bleeding history but a normal average of small dense granules had a calculated storage pool volume statistically different than controls and essentially the same storage pool volume as patients with δ-SPD. We have identified a sub-classification of δ-SPD that we have defined as micro-granular storage pool deficiency (δ-MGSPD).

Inflammatory Biomarkers in Postural Orthostatic Tachycardia Syndrome with Elevated G-Protein-Coupled Receptor Autoantibodies

“…An FEI Tecnai G2 Spirit BioTwin transmission electron microscope (TEM, Hillsboro, OR, USA) was used to determine an average number of DG/PL. Previous studies from this laboratory have established a normal of 4.64 ± 0.11 (Mean ± 1 SE DG/PL), consistent with the established literature [ 34 , 35 ].…”

“…All the patients included in the study (34) were previously reported to have elevations of autoantibodies against the Alpha 1-(A1) adrenergic receptor (Adr-R) and the Muscarinic 4 (M4) anti-muscarinic cholinergic receptor (mAChR) [18]. These autoantibodies had a correlation coefficient of r = 0.792.…”

Platelet δ-Storage Pool Disease: An Update

“…Other electron-dense structures not counted as dense-granules are large, thin semi-opaque veils ( Figure 4 A,B); poor in phosphorus and calcium [ 67 ]; with fuzzy or spongy elements ( Figure 4 D), which occur very large and numerous in STIM1–York–Stormorken syndromes [ 69 ] and clusters or chains of small beads ( Figure 4 C–E). The latter have a near-delta composition in calcium and phosphorus, but a lower P/Ca ratio for the chains, as determined by EDXA (Energy-dispersive X-ray spectroscopy .…”

Bleeding of unknown cause and unclassified bleeding disorders; diagnosis, pathophysiology and management

“…Extensive phenotyping of platelet function using light transmission aggregometry or platelet function analyser (PFA) assays in BUC/UBD patients has not been reported due to difficulties in standardization and interpretation of these tests. In a study using electron microscopy and image analysis to assess 1800 patients with unexplained bleeding for potential dense granule deficiency, it was found that 53.7% patients had a normal mean number of dense granules; however, these granules were smaller than seen in controls 40 . In addition, these patients had a decreased storage volume compared to controls and similar to patients with δ‐granule storage pool deficiency.…”