The Experts below are selected from a list of 72 Experts worldwide ranked by ideXlab platform
Hidehiko Saito - One of the best experts on this subject based on the ideXlab platform.
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Novel heterozygous missense mutation in the second leucine rich repeat of GPIbalpha affects GPIb/IX/V expression and results in macrothrombocytopenia in a patient initially misdiagnosed with idiopathic thrombocytopenic purpura.
European journal of haematology, 2006Co-Authors: Shinji Kunishima, Toshi Imai, Motohiro Hamaguchi, Hidehiko SaitoAbstract:Recent studies have shown that heterozygous carriers of the bleeding Disorder Bernard-Soulier syndrome are occasionally identified as isolated case of Giant Platelet Disorder/macrothrombocytopenia or misdiagnosed with idiopathic thrombocytopenic purpura (ITP). We describe here a patient with congenital macrothrombocytopenia who had been diagnosed with ITP. On peripheral blood smears, Platelet diameter was approximately 30% larger than normal controls. In the patient's Platelets, the expression level of the GPIbIX complex was slightly decreased (70-80% of normal control). Densitometric analysis of immunoblots showed GPIbalpha to be approximately 52% of normal. DNA sequencing analysis revealed a novel heterozygous missense mutation in the GPIbalpha gene that converts Tyr to Asp at residue 54 (Y54D) in the second leucine-rich repeat. Mutant GPIbalpha protein was not detected in the patient's Platelets. Transient transfection studies demonstrated that mutant GPIbalpha affects complex expression. These findings suggest that null expression of the mutant GPIbalpha causes decreased density of the complex and results in macrothrombocytopenia.
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novel heterozygous missense mutation in the Platelet glycoprotein ibβ gene associated with isolated Giant Platelet Disorder
American Journal of Hematology, 2001Co-Authors: Shinji Kunishima, Tomoki Naoe, T Kamiya, Hidehiko SaitoAbstract:The glycoprotein (GP) Ib/IX/V complex plays an important role in primary hemostasis, serving as the Platelet receptor for von Willebrand factor (vWF). Recent studies have shown that the phenotype caused by mutations in the subunits of the GPIb/IX complex spans a wide spectrum; from the normal phenotype, to isolated Giant Platelet Disorders (GPD), and to the full-blown bleeding Disorder, the Bernard-Soulier syndrome (BSS). We characterize here a novel missense mutation of the GPIbβ gene associated with isolated GPD. In the patient's Platelets, the expression level of the GPIb/IX complex was moderately reduced compared with that of the GPIIb/IIIa complex, whereas the latter was expressed at higher levels than in a normal control. Immunoblot analysis showed normal electrophoretic mobility of GPIbα, GPIbβ, and GPIX. However, the amount of GPIbβ was approximately 66% of the normal value. DNA sequencing analysis revealed a novel heterozygous missense mutation in the GPIbβ gene that converts Arg (CGC) to Cys (TGC) at residue 17. Transient transfection studies demonstrated that mutant GPIbβ protein was not detected in transfected 293T cells. These findings indicated that null expression of the abnormal GPIbβ causes decreased expression of the complex and results in the GPD phenotype in the patient, and suggested that homozygosity of the mutation may lead to a BSS phenotype in vivo. Am. J. Hematol. 68:249–255, 2001. © 2001 Wiley-Liss, Inc.
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mapping of a gene for may hegglin anomaly to chromosome 22q
Human Genetics, 1999Co-Authors: Shinji Kunishima, Tadashi Kamiya, Tetsuhito Kojima, Kazuo Ozawa, Yusuke Nakamura, Toshihiro Tanaka, Hidehiko SaitoAbstract:May-Hegglin anomaly (MHA) is a rare autosomal dominant Platelet Disorder characterized by the triad of Giant Platelets, thrombocytopenia and leukocyte inclusions. Both the molecular and the genetic defects responsible for this Disorder remain unknown. In order to map the gene responsible for MHA, we performed a genome-wide linkage study using highly polymorphic short tandem repeat markers in a single Japanese MHA family. Significant linkage was obtained for the markers on the long arm of chromosome 22 (22q12.3–q13.2), with a maximum two-point lod score of 4.52 at a recombination fraction of 0.00 for the markers D22S1142 and D22S277. Haplotype analysis mapped a critical region for the disease locus to a 13.6-centimorgan region, between D22S280 and D22S272. The relative proximity of the Platelet GPIb β gene (22q11.2) to this region, as well as its involvement in an isolated Giant Platelet Disorder, suggested a possible involvement of GPIb β mutations in MHA. However, DNA-sequencing analysis in two patients revealed no abnormality in the sequence of the GPIb β gene. This is the first report of linkage for MHA, and further analysis of this locus may lead to the identification of a gene the product of which regulates Platelet and leukocyte morphology.
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missense mutations of the glycoprotein gp ibβ gene impairing the gpib α β disulfide linkage in a family with Giant Platelet Disorder
Blood, 1997Co-Authors: Shinji Kunishima, Tadashi Kamiya, Hidehiko Saito, Jose A Lopez, Sentaro Kobayashi, Nobuaki Imai, Tomoki NaoeAbstract:We describe here the molecular basis of an isolated hereditary Giant Platelet Disorder (GPD) which is not accompanied with thrombocytopenia or leukocyte inclusion. Platelet aggregation with ristocetin and botrocetin was almost normal in this patient. Flow cytometric analysis showed that the glycoprotein (GP) Ib/IX complex was expressed on the Platelet membranes at decreased levels. The amount of Platelet GPIbα and the plasma glycocalicin concentration, the water-soluble extracellular portion of GPIbα, were also decreased. The anti-GPIbα antibody coprecipitated GPIbβ and GPIX, although the ratios of these polypeptides to GPIbα was greatly decreased compared with the ratio in normal Platelets. Immunoblot analysis under nonreduced conditions showed that most of the GPIbα in the patient9s Platelets was not disulfide linked with GPIbβ. DNA sequencing analysis showed compound heterozygosity for two independent single nucleotide substitutions: from Tyr (TAC) to Cys (TGC) at residue 88, and from Ala (GCC) to Pro (CCC) at residue 108 in her GPIbβ gene. These substitutions were not found in genomic DNA samples from 108 normal individuals. These mutations might result in decreased expression of the GPIb/IX complex and may influence the association of the complex with the membrane skeleton, consequently impairing normal Platelet morphology. Furthermore, the phenotype caused by mutations in the subunits of the GPIb/IX complex could span the spectrum from a normal phenotype, to isolated GPD, to a full-blown bleeding Disorder, such as Bernard-Soulier syndrome.
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Missense Mutations of the Glycoprotein (GP) Ibβ Gene Impairing the GPIb α/β Disulfide Linkage in a Family With Giant Platelet Disorder
Blood, 1997Co-Authors: Shinji Kunishima, Tadashi Kamiya, Hidehiko Saito, Jose A Lopez, Sentaro Kobayashi, Nobuaki Imai, Tomoki NaoeAbstract:We describe here the molecular basis of an isolated hereditary Giant Platelet Disorder (GPD) which is not accompanied with thrombocytopenia or leukocyte inclusion. Platelet aggregation with ristocetin and botrocetin was almost normal in this patient. Flow cytometric analysis showed that the glycoprotein (GP) Ib/IX complex was expressed on the Platelet membranes at decreased levels. The amount of Platelet GPIbα and the plasma glycocalicin concentration, the water-soluble extracellular portion of GPIbα, were also decreased. The anti-GPIbα antibody coprecipitated GPIbβ and GPIX, although the ratios of these polypeptides to GPIbα was greatly decreased compared with the ratio in normal Platelets. Immunoblot analysis under nonreduced conditions showed that most of the GPIbα in the patient9s Platelets was not disulfide linked with GPIbβ. DNA sequencing analysis showed compound heterozygosity for two independent single nucleotide substitutions: from Tyr (TAC) to Cys (TGC) at residue 88, and from Ala (GCC) to Pro (CCC) at residue 108 in her GPIbβ gene. These substitutions were not found in genomic DNA samples from 108 normal individuals. These mutations might result in decreased expression of the GPIb/IX complex and may influence the association of the complex with the membrane skeleton, consequently impairing normal Platelet morphology. Furthermore, the phenotype caused by mutations in the subunits of the GPIb/IX complex could span the spectrum from a normal phenotype, to isolated GPD, to a full-blown bleeding Disorder, such as Bernard-Soulier syndrome.
Shinji Kunishima - One of the best experts on this subject based on the ideXlab platform.
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Novel heterozygous missense mutation in the second leucine rich repeat of GPIbalpha affects GPIb/IX/V expression and results in macrothrombocytopenia in a patient initially misdiagnosed with idiopathic thrombocytopenic purpura.
European journal of haematology, 2006Co-Authors: Shinji Kunishima, Toshi Imai, Motohiro Hamaguchi, Hidehiko SaitoAbstract:Recent studies have shown that heterozygous carriers of the bleeding Disorder Bernard-Soulier syndrome are occasionally identified as isolated case of Giant Platelet Disorder/macrothrombocytopenia or misdiagnosed with idiopathic thrombocytopenic purpura (ITP). We describe here a patient with congenital macrothrombocytopenia who had been diagnosed with ITP. On peripheral blood smears, Platelet diameter was approximately 30% larger than normal controls. In the patient's Platelets, the expression level of the GPIbIX complex was slightly decreased (70-80% of normal control). Densitometric analysis of immunoblots showed GPIbalpha to be approximately 52% of normal. DNA sequencing analysis revealed a novel heterozygous missense mutation in the GPIbalpha gene that converts Tyr to Asp at residue 54 (Y54D) in the second leucine-rich repeat. Mutant GPIbalpha protein was not detected in the patient's Platelets. Transient transfection studies demonstrated that mutant GPIbalpha affects complex expression. These findings suggest that null expression of the mutant GPIbalpha causes decreased density of the complex and results in macrothrombocytopenia.
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novel heterozygous missense mutation in the Platelet glycoprotein ibβ gene associated with isolated Giant Platelet Disorder
American Journal of Hematology, 2001Co-Authors: Shinji Kunishima, Tomoki Naoe, T Kamiya, Hidehiko SaitoAbstract:The glycoprotein (GP) Ib/IX/V complex plays an important role in primary hemostasis, serving as the Platelet receptor for von Willebrand factor (vWF). Recent studies have shown that the phenotype caused by mutations in the subunits of the GPIb/IX complex spans a wide spectrum; from the normal phenotype, to isolated Giant Platelet Disorders (GPD), and to the full-blown bleeding Disorder, the Bernard-Soulier syndrome (BSS). We characterize here a novel missense mutation of the GPIbβ gene associated with isolated GPD. In the patient's Platelets, the expression level of the GPIb/IX complex was moderately reduced compared with that of the GPIIb/IIIa complex, whereas the latter was expressed at higher levels than in a normal control. Immunoblot analysis showed normal electrophoretic mobility of GPIbα, GPIbβ, and GPIX. However, the amount of GPIbβ was approximately 66% of the normal value. DNA sequencing analysis revealed a novel heterozygous missense mutation in the GPIbβ gene that converts Arg (CGC) to Cys (TGC) at residue 17. Transient transfection studies demonstrated that mutant GPIbβ protein was not detected in transfected 293T cells. These findings indicated that null expression of the abnormal GPIbβ causes decreased expression of the complex and results in the GPD phenotype in the patient, and suggested that homozygosity of the mutation may lead to a BSS phenotype in vivo. Am. J. Hematol. 68:249–255, 2001. © 2001 Wiley-Liss, Inc.
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mapping of a gene for may hegglin anomaly to chromosome 22q
Human Genetics, 1999Co-Authors: Shinji Kunishima, Tadashi Kamiya, Tetsuhito Kojima, Kazuo Ozawa, Yusuke Nakamura, Toshihiro Tanaka, Hidehiko SaitoAbstract:May-Hegglin anomaly (MHA) is a rare autosomal dominant Platelet Disorder characterized by the triad of Giant Platelets, thrombocytopenia and leukocyte inclusions. Both the molecular and the genetic defects responsible for this Disorder remain unknown. In order to map the gene responsible for MHA, we performed a genome-wide linkage study using highly polymorphic short tandem repeat markers in a single Japanese MHA family. Significant linkage was obtained for the markers on the long arm of chromosome 22 (22q12.3–q13.2), with a maximum two-point lod score of 4.52 at a recombination fraction of 0.00 for the markers D22S1142 and D22S277. Haplotype analysis mapped a critical region for the disease locus to a 13.6-centimorgan region, between D22S280 and D22S272. The relative proximity of the Platelet GPIb β gene (22q11.2) to this region, as well as its involvement in an isolated Giant Platelet Disorder, suggested a possible involvement of GPIb β mutations in MHA. However, DNA-sequencing analysis in two patients revealed no abnormality in the sequence of the GPIb β gene. This is the first report of linkage for MHA, and further analysis of this locus may lead to the identification of a gene the product of which regulates Platelet and leukocyte morphology.
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missense mutations of the glycoprotein gp ibβ gene impairing the gpib α β disulfide linkage in a family with Giant Platelet Disorder
Blood, 1997Co-Authors: Shinji Kunishima, Tadashi Kamiya, Hidehiko Saito, Jose A Lopez, Sentaro Kobayashi, Nobuaki Imai, Tomoki NaoeAbstract:We describe here the molecular basis of an isolated hereditary Giant Platelet Disorder (GPD) which is not accompanied with thrombocytopenia or leukocyte inclusion. Platelet aggregation with ristocetin and botrocetin was almost normal in this patient. Flow cytometric analysis showed that the glycoprotein (GP) Ib/IX complex was expressed on the Platelet membranes at decreased levels. The amount of Platelet GPIbα and the plasma glycocalicin concentration, the water-soluble extracellular portion of GPIbα, were also decreased. The anti-GPIbα antibody coprecipitated GPIbβ and GPIX, although the ratios of these polypeptides to GPIbα was greatly decreased compared with the ratio in normal Platelets. Immunoblot analysis under nonreduced conditions showed that most of the GPIbα in the patient9s Platelets was not disulfide linked with GPIbβ. DNA sequencing analysis showed compound heterozygosity for two independent single nucleotide substitutions: from Tyr (TAC) to Cys (TGC) at residue 88, and from Ala (GCC) to Pro (CCC) at residue 108 in her GPIbβ gene. These substitutions were not found in genomic DNA samples from 108 normal individuals. These mutations might result in decreased expression of the GPIb/IX complex and may influence the association of the complex with the membrane skeleton, consequently impairing normal Platelet morphology. Furthermore, the phenotype caused by mutations in the subunits of the GPIb/IX complex could span the spectrum from a normal phenotype, to isolated GPD, to a full-blown bleeding Disorder, such as Bernard-Soulier syndrome.
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Missense Mutations of the Glycoprotein (GP) Ibβ Gene Impairing the GPIb α/β Disulfide Linkage in a Family With Giant Platelet Disorder
Blood, 1997Co-Authors: Shinji Kunishima, Tadashi Kamiya, Hidehiko Saito, Jose A Lopez, Sentaro Kobayashi, Nobuaki Imai, Tomoki NaoeAbstract:We describe here the molecular basis of an isolated hereditary Giant Platelet Disorder (GPD) which is not accompanied with thrombocytopenia or leukocyte inclusion. Platelet aggregation with ristocetin and botrocetin was almost normal in this patient. Flow cytometric analysis showed that the glycoprotein (GP) Ib/IX complex was expressed on the Platelet membranes at decreased levels. The amount of Platelet GPIbα and the plasma glycocalicin concentration, the water-soluble extracellular portion of GPIbα, were also decreased. The anti-GPIbα antibody coprecipitated GPIbβ and GPIX, although the ratios of these polypeptides to GPIbα was greatly decreased compared with the ratio in normal Platelets. Immunoblot analysis under nonreduced conditions showed that most of the GPIbα in the patient9s Platelets was not disulfide linked with GPIbβ. DNA sequencing analysis showed compound heterozygosity for two independent single nucleotide substitutions: from Tyr (TAC) to Cys (TGC) at residue 88, and from Ala (GCC) to Pro (CCC) at residue 108 in her GPIbβ gene. These substitutions were not found in genomic DNA samples from 108 normal individuals. These mutations might result in decreased expression of the GPIb/IX complex and may influence the association of the complex with the membrane skeleton, consequently impairing normal Platelet morphology. Furthermore, the phenotype caused by mutations in the subunits of the GPIb/IX complex could span the spectrum from a normal phenotype, to isolated GPD, to a full-blown bleeding Disorder, such as Bernard-Soulier syndrome.
Gilbert C. White - One of the best experts on this subject based on the ideXlab platform.
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Giant Platelet Disorder in a patient with type 2B von Willebrand's disease
American Journal of Hematology, 1998Co-Authors: Stephan Moll, Alicia Rico Lazarowski, Gilbert C. WhiteAbstract:While patients with type 2B von Willebrand's disease often exhibit thrombocytopenia, Platelet morphology is typically normal. We describe a 44-year-old Jamaican man with thrombocytopenia and a history of bleeding, who had Giant Platelets on his peripheral blood film. Functional studies and von Willebrand factor gene sequencing showed him to have type 2B von Willebrand's disease with a heterozygous point mutation resulting in a V553M (V1316M in the new von Willebrand factor gene mutation nomenclature) amino acid substitution. Family studies showed one of his two sisters to have an ill-defined Giant-Platelet-syndrome with mild thrombocytopenia, but not von Willebrand's disease, indicating that the association of Giant Platelets and von Willebrand's disease in our patient was most likely coincidental. This report describes the rare concurrence of two uncommon Disorders. It also demonstrates how the thrombocytopenia of type 2B von Willebrand's disease can be misdiagnosed as ITP, leading to unnecessary and potentially harmful therapeutic interventions. Am. J. Hematol. 57:62–67, 1998. © 1998 Wiley-Liss, Inc.
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Giant Platelet Disorder in a patient with type 2B von Willebrand's disease
American journal of hematology, 1998Co-Authors: Stephan Moll, Alicia Rico Lazarowski, Gilbert C. WhiteAbstract:While patients with type 2B von Willebrand's disease often exhibit thrombocytopenia, Platelet morphology is typically normal. We describe a 44-year-old Jamaican man with thrombocytopenia and a history of bleeding, who had Giant Platelets on his peripheral blood film. Functional studies and von Willebrand factor gene sequencing showed him to have type 2B von Willebrand's disease with a heterozygous point mutation resulting in a V553M (V1316M in the new von Willebrand factor gene mutation nomenclature) amino acid substitution. Family studies showed one of his two sisters to have an ill-defined Giant-Platelet-syndrome with mild thrombocytopenia, but not von Willebrand's disease, indicating that the association of Giant Platelets and von Willebrand's disease in our patient was most likely coincidental. This report describes the rare concurrence of two uncommon Disorders. It also demonstrates how the thrombocytopenia of type 2B von Willebrand's disease can be misdiagnosed as ITP, leading to unnecessary and potentially harmful therapeutic interventions.
Stephan Moll - One of the best experts on this subject based on the ideXlab platform.
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Giant Platelet Disorder in a patient with type 2B von Willebrand's disease
American Journal of Hematology, 1998Co-Authors: Stephan Moll, Alicia Rico Lazarowski, Gilbert C. WhiteAbstract:While patients with type 2B von Willebrand's disease often exhibit thrombocytopenia, Platelet morphology is typically normal. We describe a 44-year-old Jamaican man with thrombocytopenia and a history of bleeding, who had Giant Platelets on his peripheral blood film. Functional studies and von Willebrand factor gene sequencing showed him to have type 2B von Willebrand's disease with a heterozygous point mutation resulting in a V553M (V1316M in the new von Willebrand factor gene mutation nomenclature) amino acid substitution. Family studies showed one of his two sisters to have an ill-defined Giant-Platelet-syndrome with mild thrombocytopenia, but not von Willebrand's disease, indicating that the association of Giant Platelets and von Willebrand's disease in our patient was most likely coincidental. This report describes the rare concurrence of two uncommon Disorders. It also demonstrates how the thrombocytopenia of type 2B von Willebrand's disease can be misdiagnosed as ITP, leading to unnecessary and potentially harmful therapeutic interventions. Am. J. Hematol. 57:62–67, 1998. © 1998 Wiley-Liss, Inc.
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Giant Platelet Disorder in a patient with type 2B von Willebrand's disease
American journal of hematology, 1998Co-Authors: Stephan Moll, Alicia Rico Lazarowski, Gilbert C. WhiteAbstract:While patients with type 2B von Willebrand's disease often exhibit thrombocytopenia, Platelet morphology is typically normal. We describe a 44-year-old Jamaican man with thrombocytopenia and a history of bleeding, who had Giant Platelets on his peripheral blood film. Functional studies and von Willebrand factor gene sequencing showed him to have type 2B von Willebrand's disease with a heterozygous point mutation resulting in a V553M (V1316M in the new von Willebrand factor gene mutation nomenclature) amino acid substitution. Family studies showed one of his two sisters to have an ill-defined Giant-Platelet-syndrome with mild thrombocytopenia, but not von Willebrand's disease, indicating that the association of Giant Platelets and von Willebrand's disease in our patient was most likely coincidental. This report describes the rare concurrence of two uncommon Disorders. It also demonstrates how the thrombocytopenia of type 2B von Willebrand's disease can be misdiagnosed as ITP, leading to unnecessary and potentially harmful therapeutic interventions.
James G White - One of the best experts on this subject based on the ideXlab platform.
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The Medich Giant Platelet syndrome: two new cases.
Platelets, 2012Co-Authors: William T. Gunning, Mukund Dole, Martin J. Brecher, James G WhiteAbstract:Hypogranular Platelet Disorders in human subjects are relatively rare. They include the gray Platelet syndrome, αδ storage pool deficiency, the Hermansky–Pudlak syndrome, and the white Platelet syndrome. Perhaps the rarest of them all is the Medich Giant Platelet Disorder. No additional cases of this condition have been reported since description of the first case in 2004. This study describes two children with thrombocytopenia and Giant, hypogranular Platelets found shortly after birth. Electron microscopic study of their Platelets revealed sheets of membrane wrapped into tubes resembling scrolls. The scroll-like structures were open at both ends and often filled with glycogen particles. The abnormal structures are identical to those found in the initial case. As a result, the Disorder can now be referred to as the Medich Giant Platelet syndrome.
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Golgi complexes in hypogranular Platelet syndromes
Platelets, 2005Co-Authors: James G WhiteAbstract:The white Platelet syndrome (WPS) is an autosomal dominantly inherited hypogranular Platelet Disorder characterized by the presence of fully developed Golgi complexes from parent megakaryocytes in 13% or more of their circulating Platelets. The present study has evaluated several other hypogranular Platelet Disorders to determine if perpetuation of Golgi complexes in circulating cells is a common link in those inherited conditions. Only Platelets from patients with the gray Platelet syndrome (GPS) and one patient with alpha delta Platelet storage pool deficiency (alpha delta SPD) had more Golgi complexes in their cells than were found in normal thrombocytes. Platelets from patients with the Hermansky-Pudlak syndrome, two other patients with alpha delta SPD and the individual with Medich Giant Platelet Disorder had the same frequency of Golgi complexes in circulating cells as normal controls. Thus, the presence of large numbers of fully developed Golgi complexes in circulating Platelets appears unique to the WPS.
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medich Giant Platelet Disorder a unique α granule deficiency i structural abnormalities
Platelets, 2004Co-Authors: James G WhiteAbstract:Human Platelet granule deficiency Disorders include the gray Platelet syndrome (GPS), α δ storage pool deficiency, the Hermansky–Pudlak syndrome and the White Platelet syndrome. The present study describes a patient with a lifelong history of easy bleeding, thrombocytopenia and Giant Platelets. Her cells were found to have normal numbers of dense bodies, but a markedly decreased number of α granules. Many Platelets had no α granules and resembled the gray Platelets of patients with GPS. However, the empty vacuoles without granule contents that fill the cytoplasm of GPS Platelets were not present in significant numbers in her Platelets. In addition to the decrease in α granules the patients Platelets contained membranous inclusions resembling cigars or scrolls. Usually, only one scroll open at each end was present, but many Platelets contained two and some as many as five. Freeze-fracture revealed an absence of intramembranous particles in many layers of the scrolls. They occur in no other human Platelet d...
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A variant of the Sebastian Platelet syndrome with unique neutrophil inclusions.
Platelets, 2002Co-Authors: James G White, Joan C. Mattson, William L. Nichols, Naomi L.c. Luban, Andreas GreinacherAbstract:The Sebastian Platelet syndrome (SPS) is a hereditary Giant Platelet Disorder characterized by thrombocytopenia and the presence of neutrophil inclusions identical to those present in neutrophils of patients with another Giant Platelet Disorder, the Fechtner Platelet syndrome (FPS). Patients with SPS differ from those with FPS in that they lack the clinical features of the Alport syndrome (high frequency hearing loss, congenital cataracts and chronic interstitial nephritis). The present study has evaluated six patients who resemble individuals with SPS, but have uniquely different neutrophil inclusions. Ultrastructural features of the neutrophil inclusions of the new variant are presented and compared with those found in other Giant Platelet Disorders including classic SPS, FPS and the May-Hegglin anomaly, as well as the Chediak-Higashi syndrome.