Gray Platelet Syndrome-Unusual Presentation with Spontaneous Splenic Rupture: A Case Report and Literature Review.

Gray platelet syndrome (GPS) is a rare hereditary hemorrhagic disorder characterized by macrothrombocytopenia and the absence of alpha-granules in platelets. Clinically, mild-to-moderate bleeding is the main manifestation, often accompanied by thrombocytopenia, splenomegaly, and myelofibrosis. Here, we present a case of a 15-year-old male patient with a history of hepatosplenomegaly, and thrombocytopenia for 8 years, who presented with sudden generalized abdominal pain. Despite initial suspicion of gastroenteritis, diagnostic imaging revealed an extensive hemoperitoneum. Subsequent genetic testing confirmed the diagnosis of GPS, which had not been previously identified. This case highlights the importance of considering inherited platelet disorders should be considered in adolescents with long-standing thrombocytopenia, and emphasizes the need for thorough evaluation in patients with suggestive symptoms.

Acquired Gray Platelet Syndrome Associated with Primary Myelofibrosis.

A 53-year-old man presented with uncontrolled bleeding caused by acquired platelet dysfunction accompanied by calreticulin-mutated primary myelofibrosis. Based on the detection of abnormal platelets, including large gray platelets, under light microscopy and the loss of the second wave of aggregation observed by light transmission aggregometry, the patient was diagnosed with platelet dysfunction accompanied by myeloproliferative neoplasms (MPNs). In addition, the absence of platelet α-granules was confirmed by electron microscopy. Therefore, this condition may be termed "acquired gray platelet syndrome." Acquired platelet dysfunction must be ruled out when abnormal platelets are observed in patients with MPNs.

A novel nonsense NBEAL2 gene mutation causing severe bleeding in a patient with gray platelet syndrome.

Gray platelet syndrome (GPS) is a rare, inherited bleeding disorder characterized by the defect of platelet α-granule. Up to date, these are only four studies identifying NBEAL2 gene correlated with GPS. In the current report, we present a Chinese GPS patient who had severe bleeding tendency, abnormalities of platelet functions, and absence of platelet α-granules. Genomic DNA sequencing for the patient identified a nonsense mutation (g.27713C>A) of NBEAL2 gene (g.NG__031914.1) resulting in a premature protein (p.Glu1726*). In comparison with the reported patients, we conclude that homozygotes with nonsense or deletion mutation leading to a premature stop codon exhibit more serious bleeding problem than those with missense mutations.

Spontaneous 8bp Deletion in Nbeal2 Recapitulates the Gray Platelet Syndrome in Mice.

During the analysis of a whole genome ENU mutagenesis screen for thrombosis modifiers, a spontaneous 8 base pair (bp) deletion causing a frameshift in exon 27 of the Nbeal2 gene was identified. Though initially considered as a plausible thrombosis modifier, this Nbeal2 mutation failed to suppress the synthetic lethal thrombosis on which the original ENU screen was based. Mutations in NBEAL2 cause Gray Platelet Syndrome (GPS), an autosomal recessive bleeding disorder characterized by macrothrombocytopenia and gray-appearing platelets due to lack of platelet alpha granules. Mice homozygous for the Nbeal2 8 bp deletion (Nbeal2gps/gps) exhibit a phenotype similar to human GPS, with significantly reduced platelet counts compared to littermate controls (p = 1.63 x 10-7). Nbeal2gps/gps mice also have markedly reduced numbers of platelet alpha granules and an increased level of emperipolesis, consistent with previously characterized mice carrying targeted Nbeal2 null alleles. These findings confirm previous reports, provide an additional mouse model for GPS, and highlight the potentially confounding effect of background spontaneous mutation events in well-characterized mouse strains.

Onyx embolization of an intraosseous pseudoaneurysm of the middle meningeal artery in a patient with meningiomatosis, McCune-Albright syndrome, and gray platelet syndrome.

A 13-year-old boy with meningiomatosis, McCune-Albright syndrome, and gray platelet syndrome presented with an enlarging "lump" on his right forehead. A head CT scan revealed a polyostotic fibrous dysplasia involving the entire skull. A 3.4-cm right frontal osseous cavity and an overlying right forehead subcutaneous soft-tissue mass were seen, measuring 5.2 cm in diameter and 1.6 cm thick. Ultrasound of the cavity and overlying mass showed swirling of blood and an arterialized waveform. MRI revealed an en plaque meningioma underlying the cavity. An intraosseous pseudoaneurysm fed by 3 distal anterior division branches of the right middle meningeal artery (MMA) with contrast extravasation was found on angiography. Two MMA feeders were embolized with Onyx, with anterograde filling of the intraosseous cavity with Onyx. A small pocket of residual intracavity contrast filling postembolization from a smaller third MMA feeder eventually thrombosed and the forehead lump regressed.

A case of gray platelet syndrome masked by immune thrombocytopenia at presentation.

We report a case of gray platelet syndrome (GPS) associated with immune thrombocytopenia (ITP) at presentation. A 22-year-old male patient presenting with petechiae on his limbs was diagnosed with ITP due to a gradual decrease of his platelet count to a minimum of 26 × 10(9) /liter and an elevated platelet-associated IgG (PA-IgG) level in the absence of any other specific cause of thrombocytopenia. Administration of prednisolone increased his platelet count, but this dropped again to approximately 50 × 10(9) /liter as the dose was tapered, and remained at the same level after the treatment was terminated. Thirteen years later, we reassessed the cause of the thrombocytopenia because the PA-IgG level was found to be within the normal range. There were large hypogranular platelets on the blood film and a deficit of α-granules in the platelets on electron microscopy. On this basis, we diagnosed his thrombocytopenia as GPS. To our knowledge, this is the first report of a GPS case associated with ITP at presentation. This case illustrates the importance of carefully reviewing blood film results in the differential diagnosis of thrombocytopenia.

Thrombocytopenias due to gray platelet syndrome or THC2 mutations.

Over the last two decades the genetic causes of several Mendelian platelet disorders have been elucidated, while the genetics of many other thrombocytopenic conditions are still unresolved. Among those are the gray platelet syndrome (GPS) and the thrombocytopenia linked to the THC2 locus on human chromosome 10p11-12. GPS is an α-granule defect associated with the development of myelofibrosis and mild to moderate thrombocytopenia. Most forms of GPS are autosomal recessive, and recently, the recessive form of the disease was mapped to chromosome 3p21. THC2-linked thrombocytopenia is an autosomal dominant disorder in which affected family members have a mild reduction in platelet counts and occasional bleeding. Platelets in THC2-linked thrombocytopenia appear to be normal in size and function although bone marrow morphology reveals a lack of mature, polyploid megakaryocytes. To date, mutations in three different genes within the THC2 locus have been associated with congenital thrombocytopenia, including a mutation in MASTL. In this article, we summarize the recent discoveries in these two forms of thrombocytopenia, including the functional data that support a role for MASTL kinase in thrombopoiesis.

[Grey platelet disease]. / Síndrome da plaqueta cinzenta.

Grey Platelet disease is a rare disease characterized by morphologic changes in platelets alpha-granules. These proteins are essential for the homeostasis, so the patients with this blood defect present hemorrhagic disturbs. The blood discrasia is usually mild, however some patients could present more serious manifestations, usually after a severe trauma. The authors present the following clinical report about a patient that was admitted in a Medical Department with a severe bleeding and mild thrombocytopenia. The patient was submitted to an extensive study to determine the etiology (autoimmunity serology, myelogram, coagulation study) that were all normal. The diagnosis of Idiopathic Thrombocytopenic Purpura was considered. Six months after a worsening of the hemorrhagic discrasia and thrombocytopenia the patient was assisted. Corticotherapy was initiated without improvement. The morphology of the platelets was revised and the blood smear with Wright coloration revealed the presence of large, pale and grey platelets. The electronic microscopy confirmed the diagnosis of Grey Platelet disease. The family of the patient was studied and we found that two direct relatives were affected with the same disease. In these family these syndrome probably has autossomic dominant inherence.