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HEMOSTASIS, THROMBOSIS, AND VASCULAR BIOLOGY
From the Medical Genetics Service, IRCCS Hospital CSS,
Foggia; the Department of Internal Medicine, IRCCS San
Matteo-University of Pavia; the Department of Pediatrics, II University
of Najoli; the Department of Pediatric Hematology, Azienda Santobono,
Pausilipon, Najoli; and the Department of Biomedicine of Evolutive Age,
University of Bari, Italy.
A form of autosomal dominant macrothrombocytopenia is
characterized by mild or no clinical symptoms, normal platelet
function, and normal megakaryocyte count. Because this condition
has so far received little attention, patients are subject to
misdiagnosis and inappropriate therapy. To identify the molecular basis
of this disease, 12 Italian families were studied by linkage analysis and mutation screening. Flow cytometry evaluations of platelet membrane
glycoproteins (GPs) were also performed. Linkage analysis in 2 large
families localized the gene to chromosome 17p, in an interval
containing an excellent candidate, the GPIb Inherited thrombocytopenias were, in the
past, considered exceedingly rare. Today the widespread diffusion of
electronic cell counters has rendered the identification of these
conditions more common, and many asymptomatic patients are discovered
during routine blood analysis, often in adulthood. The hereditary
nature of the illness may be missed, and patients are subject
to misdiagnosis of autoimmune thrombocytopenic purpura
and inappropriate therapy, such as steroid treatment and
splenectomy.1-3
Different diagnostic parameters have been used to classify these
disorders, including degree of bleeding, inheritance trait, platelet
function and kinetics, and concomitant clinical
abnormalities.4 The simplest classification relies on mean
platelet volume (MPV), which separates macrothrombocytopenia from
thrombocytopenia with normal MPV. Despite the lack of epidemiologic
data, clinical practice suggests that the former are more frequent than
the latter.
Patients with increased platelet size have been reported since the
nineteenth century.5 In the first half of twentieth century, authors reported the genetic basis of some platelet
macrocytoses associated with thrombocytopenia and described 2 distinct
entities, Bernard-Soulier syndrome (BSS)6 and May-Hegglin
anomaly (MHA).7,8 Over the following 5 decades, the
molecular basis of BSS9 and MHA was
clarified.10
Moreover, other forms of inherited macrothrombocytopenia have been
described The molecular mechanisms that cause hereditary giant platelet disorders
are not known in detail except those for BSS. In this case, giant
platelets are caused by defects in the platelet glycoprotein (GP)
Ib/IX/V complex, a platelet receptor for von Willebrand factor (vWF)
and the major membrane GP system that interacts with the platelet
cytoskeleton.9 Patients with BSS were found to be homozygotes or compound heterozygotes for mutations in the GPIb To identify the molecular defect of autosomal dominant hereditary
macrothrombocytopenia, we studied 12 consecutive patients and their
relatives. By evaluating platelet surface GPs and using molecular
biology techniques, we concluded that macrothrombocytopenia was
compatible with a heterozygous status of BSS in 10 patients. Of
particular interest, a missense mutation of the GPIb Clinical findings and laboratory evaluation of patients
Platelet aggregation
Genome-wide search and linkage analysis of candidate loci High-molecular-mass DNA was extracted from peripheral blood leukocytes in an automatic DNA extractor, according to the manufacturer's recommendations (ABI 341 GenePure; Applied Biosystems, Foster City, CA). For genome-wide search, genomic DNA samples from patients from 2 large families, TP-1 and TP-2, were used for linkage analysis (Figure 1). Genotyping was performed using an ABI Prism 377 DNA sequencer (ABI 377A) and the Linkage Mapping Set Version 2 (both Applied Biosystems). This set comprises 400 fluorescently labeled markers that define a 10-cM resolution human map. Prescreening was performed using only the 8 affected DNA samples from family TP-1 (Figure 1). Microsatellite mapping excluded most of the genome and identified a few loci at which patients had the same allele. The markers of candidate regions were then tested in all pedigree members, including those of family TP-2. Classic 2-point LOD score analysis was conducted in these pedigrees under the assumption of autosomal dominant inheritance and complete genetic penetrance. We used the MLink program included in the Linkage package (Applied Biosystems) to perform linkage analysis.16
Molecular analysis of the GPIb  gene (GenBank accession numbers NM000173 and
AC004771) was completely sequenced in one patient from families TP-1
and TP-2. The coding region, the untranslated exon 1, the donor and
acceptor splicing sites,17 and the promoter18
were amplified using the following oligonucleotide sets: 1F
(5'-TGGAGAGGTTTTTAAAAGATG-3') and 2R
(5'-ACCTTGCTTCCATACGTAGAC-3'); 3F (5'-CCCCTGGTTATGCAACTGTG-3') and 3R
(5'-TGGATGCAAGGAGGAGGGCAT-3'); 4F (5'-GATTACTACCCAGAAGAGGACA-3') and 5R
(5'-CACAGGCTCTTCTCTCAAGG-3'). To analyze the region containing the
VNTR polymorphism better, two new primers were synthesized, 7F
(5'-ACACTTCACATGGAATCCAT-3') and 7R (5'-GGATTCTAAGAGTGATACGGGT-3'). To
separate the alleles, the polymerase chain reaction (PCR) product was
electrophoresed on 3% agarose gel before sequencing.
PCR was performed in 50 µL containing 50 ng DNA, 15 pmol each primer, 2.5 mM MgCl2, 10 mM Tris-HCl (pH 7.5), 50 mM KCl, 0.01% Tween-20, 0.01% gelatin, 0.01% NP40, and 2 U Taq polymerase. Initial denaturation was 5 minutes at 94°C followed by amplification for 30 cycles with denaturation at 94°C for 30 seconds, annealing at 60°C for 45 seconds, and extension at 72°C for 45 seconds. After electrophoresis, PCR products were isolated and purified by GFX DNA and a Gel Band Purification Kit (Amersham, Pharmacia, Biotech, Buckinghamshire, England). Sequence analysis was performed using a fluorescence-labeled dideoxy-nucleotide termination method (dye terminator) in the automated DNA sequencer ABI 377A (Applied Biosystems). Both PCR oligonucleotides and specific internal primers were used in the sequencing reactions. To confirm and detect the Ala156Val substitution, genomic DNA was amplified using primers 2F (5'-CACCCCATCTGTGAGGTCTCC-3') and 3R (see above). Because the substitution creates a restriction enzyme site for HpaI,19 PCR products were purified, digested with the specific enzyme, and electrophoresed on 2% agarose gel. Flow cytometry The expression of platelet membrane GPs was investigated by flow cytometry with the following monoclonal antibodies (mAbs): SZ21 (Immunotech SA, Marseille, France), which recognizes GPIIIa (CD61); AP2 (Immunotech), which recognizes GPIIb/IIIa (CD41/61); MB45 (CLB, Amsterdam, The Netherlands) and SZ2 (Immunotech) against GPIb
(CD42b); FMC25 (kindly provided by Zola H, Adelaide, Australia) and SZ1
(Immunotech), which recognizes GPIX (CD42a); SW16 (CLB) against GPV
(CD42d); FA6-152 and Gi9 (both from Immunotech) against GPIV (CD36) and
GPIa (CD49b), respectively. MO2 (Coulter, Miami, FL) was
used as the negative control. Fluorescein isothiocyanate-conjugated goat anti-mouse IgG (GAM-FITC) was also purchased from Coulter.
PRP and PPP were obtained from blood anticoagulated with EDTA (final concentration, 10 mM) as described above for the platelet aggregation studies. PRP was adjusted to 50 × 109 platelets/L with PPP and fixed with 0.2% paraformaldehyde for 5 minutes at room temperature. Samples of 100 µL were incubated for 30 minutes at room temperature with 10 µL of the working solution of each mAb. Platelets were then washed with phosphate-buffered saline (PBS) containing 3.0 mM EDTA and 5% (wt/vol) bovine serum albumin (Sigma), resuspended in 100 µL PBS and incubated for 30 minutes at room temperature in the dark with an equal volume of GAM-FITC diluted 1/50 in the same buffer. After an additional wash, cells were resuspended in 300 µL PBS containing 0.3 mM EDTA and 0.1% bovine serum albumin and were analyzed with an Epics XL flow cytometer (Coulter). Platelets were identified on the basis of their size (linear forward scatter) and granularity (log side scatter), and an electronic gate was drawn around the platelet cloud to exclude residual erythrocytes and white cells. Ten thousand platelet events were collected, and the value of mean fluorescence, expressed in arbitrary units, was recorded. A sample from a healthy donor was run with the patients' samples (the same healthy donor was used for all patients).
Clinical and laboratory data Twelve patients from unrelated Italian families affected by hereditary macrothrombocytopenia were enrolled in this study (Table 1). Clinical and laboratory investigations of their available relatives identified 34 additional subjects with quantitative or qualitative platelet defects. All had larger than normal platelets, and a platelet count lower than 150 × 109/L was observed in 29 of 34 subjects. The disease was transmitted within the families as an autosomal dominant trait (Figure 1).The male-female ratio of the 46 affected subjects was 1:1, and their ages ranged from 1 to 70 years. They had platelet counts from 22 to 178 × 109/L. The mean value of MPV was 12.6 fL, with a range from 10.4 to 17.2 fL. In vitro platelet aggregation after ADP, collagen, and ristocetin was normal in all investigated patients (data not shown). Twenty-two patients had mild to moderate bleeding tendency consisting of frequent episodes of epistaxis, gingival bleeding, menorrhagia, easy bruising, or prolonged bleeding after dental surgery. Six patients from 5 families (TP-1, TP-2, TP-4, TP-5, and TP-7) underwent bone marrow examination that showed normal numbers of megakaryocytes. In some patients, however, the analysis did reveal mild and aspecific dysmegakaryocytopoietic phenomena, such as increased fraction of precursor cells and reduced megakaryocytes that appeared to be producing platelets. Genome-wide search To localize the gene(s) responsible for hereditary macrothrombocytopenia, we considered 2 large pedigrees, TP-1 and TP-2, for the genome-wide search (Figure 1). Under the assumption of complete genetic penetrance, the gene was mapped to chromosome 17q. Marker D17S938 gave a maximum 2-point LOD score of 7.51 at recombination fraction of 0.00.Haplotype analysis was performed in both families (Figure 1). In TP-1,
a telomeric recombination was evident between D17S831 and D17S938 in
subjects I-1, II-4, III-1, and III-6. In TP-2, 2 recombination events
in 2 healthy subjects, IV-6 and IV-7, established the centromeric limit
of the disease region between D17S938 and D17S1852. Therefore, the
candidate region was defined in an interval of approximately 18 cM
between microsatellites D17S831 and D17S1852. Among possible disease
candidates, GPIb Mutation analysis The GPIb gene was completely sequenced in 2 probands from each
of the TP-1 and TP-2 families. The screening identified a heterozygous
C > T transition at position 515 in both patients (data not
shown). This mutation, previously reported as the Bolzano variant,
causes an Ala156Val amino acid substitution and creates a restriction
enzyme site for HpaI.19 Restriction analysis in all family members showed that only the affected subjects were heterozygous for the missense mutation, indicating a full concordance within families between the phenotypic expression and the protein variant. Restriction analysis in the remaining 10 families allowed us
to identify the same variant in the heterozygous state in 4 of them. In
conclusion, 6 of 12 affected families had the Bolzano variant. The
change was absent in 50 unaffected, unrelated control subjects.
Flow cytometry To investigate for possible defects of the platelet surface, the major membrane GPs were investigated in 10 of 12 patients and some of their relatives (the 2 unavailable patients were carriers of the Bolzano variant). The most abundant surface protein, GPIIb-IIIa, which acts as a receptor mainly for fibrinogen during platelet activation,20 was normal or increased in all subjects (Figure 2). Similar results were obtained for GPIa and GPIV, which are receptors for collagen21 and thrombospondin,22 respectively (data not shown). Conversely, the patterns of binding to the single components of the GPIb/IX/V complex differed between the affected subjects. Representative flow cytometry tracings are shown in Figure 2. Fluorescence was clearly reduced in 8 (including all those with the Bolzano variant) of 10 patients and in their respective affected relatives (Figure 2A-B). GPIb/IX/V complex was normal or increased in the other 2 patients (Figure 2C).
Among platelets with reduced fluorescence, alternative mAbs against
GPIb On the basis of these studies, we grouped patients into 3 categories. The first group consisted of subjects with the Bolzano mutation and typical Bolzano platelet GP profile (8 patients from 4 families). The second group consisted of patients without the Bolzano variant but with a defective GPIb/IX/V complex characterized by a BSS profile of fluorescence (12 subjects from 4 families). The third group consisted of patients without the Bolzano mutation and a non-BSS profile defined by normal or increased binding of anti-GPIb/IX/V mAbs (3 subjects from 2 families). The mean of the fluorescence measurements obtained from patients of the
3 distinct groups was normalized to that from control subjects (Figure
3A). The histogram showed a clear
difference in vWF receptor content in heterozygous subjects with BSS
and in thrombocytopenic patients without the BSS phenotype. The
GPIb/IX/V defect appeared to be more significant when we normalized the data to the GPIIb/IIIa (Figure 3B).
To understand the molecular basis of chronic macrothrombocytopenia transmitted as an autosomal dominant trait, we studied 12 consecutive Italian patients and their relatives. Family investigation identified another 34 subjects with either macrothrombocytopenia or platelet macrocytosis. Clinical manifestations were absent or mild; when they were present, common clinical findings were excessive ecchymoses, frequent epistaxis, gingival bleeding, prolonged menstrual periods, or prolonged bleeding after tooth extraction. No patients or their relatives reported serious surgical or obstetric hemorrhagic complication. Genome-wide search in 2 large families localized a gene responsible for
macrothrombocytopenia in a region of chromosome 17p containing the gene
for GPIb On the basis of linkage analysis, we hypothesized that autosomal
dominant macrothrombocytopenia could be a mild form of BSS deriving
from mutations of GPIb Among the patients without the Bolzano variant, flow cytometry studies
identified a defect of the GPIb/IX/V complex in 4 of 6. In these 4 patients, the clinical findings, the hereditary pattern, and the
reduction of the GPIb/IX/V complex were consistent with a heterozygous
form of BSS. The screening for mutations of GPIb In conclusion, 10 of 12 patients, originally diagnosed as affected by
autosomal dominant macrothrombocytopenia, had a heterozygous BSS
phenotype, as determined by platelet GP analysis. In 6 patients, the
diagnosis was supported by the presence of a mutation in the GPIb Because BSS is classically described as a recessive disorder,
heterozygous subjects are expected to be asymptomatic. Although little
attention has so far been devoted to these subjects, a careful search
in the literature allowed us to collect data on 38 heterozygous
relatives of BSS patients.27-37 Some were indeed asymptomatic, whereas others had from mild to moderate bleeding diatheses. Platelet count was reduced (lowest value
80 × 109/L) in 9 of 23 subjects, MPV was increased in 17 of 23, and a defect of GPIb-IX-V complex was observed in 25 of 36. Moreover, one white family has been reported in whom a mild form of BSS was transmitted with an autosomal dominant mechanism.14
Literature data and our experience suggest that most patients with
heterozygous BSS have a reduced platelet count, recognizable defect of
GPIb-IX-V complex, or increased MPV There are 2 possible explanations for the high prevalence of the Bolzano variant in our sample. First, the mutation has such a detrimental action on platelet production that its effect is detectable in the heterozygous state. Second, this allele has a relatively high frequency in the Italian population. However, because qualitative and quantitative platelet abnormalities were previously described in heterozygous carriers for other BSS mutations27-37 and 3 of 6 Italian BSS chromosomes (all those characterized for mutations) carried the Bolzano variant,19,23,25 we favor the second hypothesis. On this basis, the results of our investigation are most relevant to Italian populations, and we cannot exclude that different results would be obtained in other countries. Heterozygous patients with BSS patients, like homozygous patients,9 show a wide spectrum of clinical and platelet findings. The heterogeneity is likely due to several factors, such as the effect of different mutations and the genetic background, which influence variability not only among families but also among members of the same family. Therefore, the severity of BSS ranges from irrelevant to moderate and from moderate to severe in heterozygous and homozygous patients, respectively. The current classification of BSS as a recessive disorder hampers the diagnosis of those symptomatic, heterozygous patients whose illness is transmitted as a dominant trait. Based on data reported concerning European, North American, and Japanese populations, the frequency of homozygous BSS has been estimated to be approximately 1 in 1 million,9 and, according to the Hardy-Weinberg law, the frequency of heterozygotes is 1 in 500. However, the proportion of heterozygous subjects with low platelet count, bleeding tendency, or both is unknown. In fact, the diagnosis is almost always missed when there are no homozygous BSS patients in the family. Therefore, a heterozygous BSS condition must be suspected in patients with autosomal dominant thrombocytopenia or platelet macrocytosis.
We thank Prof Mario Cazzola (Institute of Haematology, IRCCS San
Matteo-University of Pavia) for referring to us one of the investigated
families and Dr Maurizio Margaglione (IRCCS Hospital CSS) for providing
some of the GPIb
Submitted August 28, 2000; accepted November 7, 2000.
Supported by grants from the Italian Ministry of Health (A.S., C.B., A.I.), MURST, and 60% University of Bari (A.I.). M.S. is the recipient of a fellowship from the Italian Foundation of Cancer Research.
The publication costs of this article were defrayed in part by page charge payment. Therefore, and solely to indicate this fact, this article is hereby marked "advertisement" in accordance with 18 U.S.C. section 1734.
Reprints: Carlo Balduini, Medicina Interna, IRCCS San Matteo, Piazzale Golgi, 27100 Pavia, Italy; e-mail: c.balduini{at}smatteo.pv.it.
1. Kurtjens R, Bolt C, Vossen M, Haanen C. Familial thrombopathic thrombocytopenia. Br J Haematol. 1968;15:305-317[Medline] [Order article via Infotrieve]. 2. Nayean Y, Lecompte T. Genetic thrombocytopenia with autosomal dominant transmission: a review of 54 cases. Br J Haematol. 1990;74:203-208[Medline] [Order article via Infotrieve]. 3. Noris P, Spedini P, Belletti S, Magrini U, Balduini CL. Thrombocytopenia, giant platelets, and leukocyte inclusion bodies (May-Hegglin anomaly): clinical and laboratory findings. Am J Med. 1998;104:355-360[CrossRef][Medline] [Order article via Infotrieve]. 4. Lecompte T. Hereditary thrombocytopenia. Curr Stud Hematol Blood Transfus. 1988;55:162-173. 5. Osler W. On certain problems in the physiology of the blood corpuscles. Med News. 1886;48:365-375. 6. Bernard J, Soulier JP. Sur une nouvelle variété de dystrophie thrombocytaire hemorragique congenitale. Semaine des Hôpitaux de Paris. 1948;24:3217-3223. 7. May R. Leukozyteneinschlusse. Deutsch Arck Klin Med. 1909;96:439-440. 8. Hegglin R. Gleichzeitige Konstilutionelle veran-derungen an neutrophilen und thrombocyten. Helv Med Acta. 1945;12:439-440.
9.
Lopez JA, Andrews RK, Afshar-Kharghan V, Berndt MC.
Bernard-Soulier syndrome.
Blood.
1998;91:4397-4418 10. The May-Hegglin/Fechtner Syndrome Consortium. Mutations in MYH9 result in the May-Hegglin anomaly, and Fechtner and Sebastian syndromes. Nat Genet. 2000;26:103-105[CrossRef][Medline] [Order article via Infotrieve] 11. Mhawech P, Saleem A. Inherited giant platelet disorders: classification and literature review. Am J Clin Pathol. 2000;113:176-190[CrossRef][Medline] [Order article via Infotrieve].
12.
von Behrens WE.
Mediterranean macrothrombocytopenia.
Blood.
1975;46:199-208 13. Fabris F, Cordiano I, Salvan F, et al. Chronic isolated macrothrombocytopenia with autosomal dominant transmission: a morphological and qualitative platelet disorder. Eur J Haematol. 1997;58:40-45[Medline] [Order article via Infotrieve].
14.
Miller JL, Lyle VA, Cunningham D.
Mutation of leucine-57 to phenylalanine in a platelet glycoprotein Ib alpha leucine tandem repeat occurring in patients with an autosomal dominant variant of Bernard-Soulier disease.
Blood.
1992;79:439-446 15. Born GVR. Aggregation of blood platelets by adenosine diphosphate and its reversal. Nature. 1962;194:927-929[Medline] [Order article via Infotrieve].
16.
Lathrop GM, Lalouel JM, Julier C, Ott J.
Strategies for multilocus linkage analysis in humans.
Proc Natl Acad Sci U S A.
1984;81:3443-3446 17. Wenger RH, Kieffer N, Wicki AN, Clemetson KJ. Structure of the human blood platelet membrane glycoprotein Ib alpha gene. Biochem Biophys Res Commun. 1988;156:389-395[CrossRef][Medline] [Order article via Infotrieve]. 18. Wenger RH, Wicki AN, Kieffer N, Adolph S, Hameister H, Clemetson KJ. The 5' flanking region and chromosomal localization of the gene encoding human platelet membrane glycoprotein Ib alpha. Gene. 1989;85:517-524[CrossRef][Medline] [Order article via Infotrieve].
19.
Ware J, Russel SR, Marchese P, et al.
Point mutation in a leucine-rich repeat of platelet glycoprotein Ib
20.
Shattil SJ, Kashiwagi H, Pamporri N.
Integrin signaling: the platelet paradigm.
Blood.
1998;91:2645-2657
21.
Greenwalt DE, Lipsky RH, Ockenhouse CF, Ikeda H, Tandon NN, Jamieson GA.
Membrane glycoprotein CD36: a review of its roles in adherence, signal transduction and transfusion medicine.
Blood.
1992;80:1105-1115
22.
Smith C, Estavillo D, Emsley J, Bankston LA, Liddington RC, Cruz MA.
Mapping the collagen-binding site in the I domain of the glycoprotein Ia/IIa (integrin alpha(2)beta(1)).
J Biol Chem.
2000;275:4205-4209 23. Margaglione M, D'Andrea G, Grandone E, Brancaccio V, Amoriello A, Di Minno G. Compound heterozygosity (554-589 del, C515-T transition) in the platelet glycoprotein Ib alpha gene in a patient with a severe bleeding tendency. Thromb Haemost. 1999;81:486-492[Medline] [Order article via Infotrieve]. 24. Koskela S, Javela K, Jouppila J, et al. Variant Bernard-Soulier syndrome due to homozygous Asn45Ser mutation in the platelet glycoprotein (GP) IX in seven patients of five unrelated Finnish families. Eur J Haematol. 1999;62:256-264[Medline] [Order article via Infotrieve]. 25. Noris P, Arbustini E, Spedini P, Belletti S, Balduini CL. A new variant of Bernard-Soulier syndrome characterized by dysfunctional glycoprotein (GP) Ib and severely reduced amounts of GPIX and GPV. Br J Haematol. 1998;103:1004-1013[CrossRef][Medline] [Order article via Infotrieve] 26. López JA. The platelet glycoprotein Ib-IX complex. Blood Coagul Fibrinolysis. 1994;5:97-119[Medline] [Order article via Infotrieve]. 27. Arai M, Yamamoto N, Akamatsu N, et al. Substantial expression of glycoproteins IX and V on the platelet surface from a patient with Bernard-Soulier syndrome. Br J Haematol. 1994;87:185-188[Medline] [Order article via Infotrieve].
28.
Kunishima S, Miura H, Fukutani H, et al.
Bernard-Soulier syndrome Kagoshima: Ser 444 29. Noda M, Fujimura K, Takafuta T, et al. Heterogeneous expression of glycoprotein Ib, IX and V in platelets from two patients with Bernard-Soulier syndrome caused by different genetic abnormalities. Thromb Haemost. 1995;74:1411-1415[Medline] [Order article via Infotrieve]. 30. Li C, Pasquale DN, Roth GJ. Bernard-Soulier syndrome with severe bleeding: absent platelet glycoprotein Ib alpha due to a homozygous one-base deletion. Thromb Haemost. 1996;76:670-674[Medline] [Order article via Infotrieve].
31.
Afshar-Kharghan V, Lopez JA.
Bernard-Soulier syndrome caused by a dinucleotide deletion and reading frameshift in the region encoding the glycoprotein Ib alpha transmembrane domain.
Blood.
1997;90:2634-2643 32. Kanaji T, Okamura T, Kurolwa M, et al. Molecular and genetic analysis of two patients with Bernard-Soulier syndrome-identification of new mutations in glycoprotein Ib alpha gene. Thromb Haemost. 1997;77:1055-1061[Medline] [Order article via Infotrieve]. 33. Kunishima S, Lopez JA, Kobayashi S, et al. Missense mutations of the glycoprotein (GP) Ib beta gene impairing the GPIb alpha/beta disulfide linkage in a family with giant platelet disorder. Blood. 1997;897:2404-2412.
34.
Kenny D, Jonsson OG, Morateck PA, Montgomery RR.
Naturally occurring mutations in glycoprotein Ib 35. Van Geet C, Devriendt K, Eyskens B, Vermylen J, Hoylaerts MF. Velocardiofacial syndrome patients with a heterozygous chromosome 22q11 deletion have giant platelets. Pediatr Res. 1998;44:607-611[Medline] [Order article via Infotrieve]. 36. Koskela S, Javela K, Jouppila J, et al. Variant Bernard-Soulier syndrome due to homozygous Asn45Ser mutation in the platelet glycoprotein (GP) IX in seven patients of five unrelated Finnish families. Eur J Haematol. 1999;62:256-264. 37. Koskela S, Partanen J, Salmi TT, Kekomaki R. Molecular characterization of two mutations in platelet glycoprotein (GP) Ib alpha in two Finnish Bernard-Soulier syndrome families. Eur J Haematol. 1999;62:160-168[Medline] [Order article via Infotrieve].
© 2001 by The American Society of Hematology.
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  C. Ghevaert, A. Salsmann, N. A. Watkins, E. Schaffner-Reckinger, A. Rankin, S. F. Garner, J. Stephens, G. A. Smith, N. Debili, W. Vainchenker, et al. A nonsynonymous SNP in the ITGB3 gene disrupts the conserved membrane-proximal cytoplasmic salt bridge in the {alpha}IIb{beta}3 integrin and cosegregates dominantly with abnormal proplatelet formation and macrothrombocytopenia Blood, April 1, 2008; 111(7): 3407 - 3414. [Abstract] [Full Text] [PDF]
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 G.W. Stewart and M. Makris Mediterranean macrothrombocytopenia and phytosterolaemia/sitosterolaemia Haematologica, February 1, 2008; 93(2): e29 - e29. [Full Text] [PDF]
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A. T. Nurden and P. Nurden Inherited thrombocytopenias Haematologica, September 1, 2007; 92(9): 1158 - 1164. [Full Text] [PDF]
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A. Savoia, C. Dufour, F. Locatelli, P. Noris, C. Ambaglio, V. Rosti, M. Zecca, S. Ferrari, F. di Bari, A. Corcione, et al. Congenital amegakaryocytic thrombocytopenia: clinical and biological consequences of five novel mutations Haematologica, September 1, 2007; 92(9): 1186 - 1193. [Abstract] [Full Text] [PDF]
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K. Freson, R. De Vos, C. Wittevrongel, C. Thys, J. Defoor, L. Vanhees, J. Vermylen, K. Peerlinck, and C. Van Geet The TUBB1 Q43P functional polymorphism reduces the risk of cardiovascular disease in men by modu |
Top
Abstract
Introduction
gray platelet syndrome, platelet-type von Willebrand disease, Montreal platelet syndrome, macrothrombocytopenia with mitral
valve insufficiency, familial macrothrombocytopenia with glycoprotein
(GP) IV abnormality, Epstein, Fechtner, and Sebastian syndromes
, or GPIX genes, 3 of the 4 distinct gene products of the GPIb/IX/V complex. Only one family characterized by mild clinical symptoms was described as having autosomal dominant BSS.
stop mutation of glycoprotein (GP) Ib alpha resulting in circulating truncated GPIb alpha and surface expression of GPIb beta and GPIX.
Blood.
1994;84:3356-3362