Role of five platelet membrane glycoprotein polymorphisms in branch retinal vein occlusion.

To determine whether polymorphisms of platelet surface glycoprotein associated with arterial thrombosis are risk factors for branch retinal vein occlusion. A case-control study in which 69 patients with branch retinal vein occlusion and 147 controls who attended the eye clinic for nonvascular complications participated. DNA was extracted from whole blood and analyzed for genotyping of platelet glycoprotein polymorphisms by polymerase chain reactions and specific restricted enzymes. No relationship was found between the four platelet glycoprotein polymorphisms i.e. GPIa C807T, VNTR and Kozak of glycoprotein Ibalpha, the HPA-1 of glycoprotein IIIa and the occurrence of branch retinal vein occlusion. The HPA-2 polymorphism was found in 18 out 60 (30%) patients with branch retinal vein occlusion in comparison with 27 out 142 (19%) of controls, with an estimated odds ratio of 1.8 (95% confidence interval, 0.91-3.65). The four platelet glycoprotein polymorphisms are not risk factors for branch retinal vein occlusion and therefore it seems unnecessary to screen those patients for it. A larger study is required, however, to determine whether HPA-2 is a novel risk factor for branch retinal vein occlusion.     

Platelet glycoprotein Ibalpha Kozak polymorphism is associated with an increased risk of ischemic stroke.

Platelets are pivotal to the process of arterial thrombosis resulting in ischemic stroke. Occlusive thrombosis is initiated by the interaction of von Willebrand factor (vWf) and platelet glycoprotein (GP) Ibalpha. Three polymorphisms have been described in GP Ibalpha (Kozak T/C polymorphism, variable number of tandem repeats [VNTR], and the human platelet antigen 2a [HPA-2a] [Thr] or HPA-2b [Met] at position 145), each of which may enhance the vWf and GP Ibalpha interaction. This study investigated whether these polymorphisms are candidate genes for first-ever ischemic stroke. A hospital-based case-control study was conducted of 219 cases of first-ever ischemic stroke and 205 community controls randomly selected from the electoral roll and stratified by age, sex, and postal code. The subtypes of stroke were classified, the prevalence of conventional risk factors was recorded, and blood was collected to perform genotyping analysis for Kozak C or T alleles, VNTR, and HPA-2a/b. It was found that the Kozak T/C genotype was over-represented in the stroke group (32.2%) compared with controls (22.8%) (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.03-2.54; P <.03), and the association was still present even after adjusting for conventional risk factors. There was a trend in the increased prevalence of HPA-2a/b in stroke patients (15%) compared with controls (9.9%) (adjusted OR, 1.8; 95% CI, 0.94-3.4; P =.07). No associations were seen with the VNTR polymorphism or with any of the polymorphisms with stroke subtype. It was concluded that the Kozak T/C polymorphism, which is associated with an increase in platelet GP Ibalpha surface expression, is an independent risk factor for first-ever ischemic stroke.     

脑梗死患者血小板膜糖蛋白Ⅰ bα基因HPA-2、Kozak位点多态性分析

目的观察脑梗死患者血小板膜糖蛋白（GP）Ⅰbα基因HPA-2、Kozak位点多态性,探讨其与脑梗死的关系。方法选取316例经CT或MR I证实的脑梗塞患者（观察组）及209例无脑血管疾病者（对照组）,采用聚合酶链反应—限制性片断长度多态性（PCR-RFLP）法检测GPⅠbα基因HPA-2、Kozak位点多态性,用流式细胞术（FCM）测定血小板活化标志物CD62P、CD63的表达。结果观察组血小板GPⅠbα基因HPA-2位点基因型分布及等位基因频率与对照组相比P均〉0.05;观察组Kozak位点观察组基因型为CC者20例、CT者113例、TT者169例,等位基因C频率为25.33%、T频率为74.67%;对照组分别为6、28、162例和10.20%、89.80%。两组基因型分布和等位基因C、T频率相比,P均〈0.05。观察组表达等位基因C者（基因型CC＋CT）CD62P表达量为20.94±7.35、CD63表达量为28.62±9.47,不表达等位基因C者（基因型为TT）分别为13.36±6.27、20.27±5.45,二者CD62P、CD63表达量相比P均〈0.05。结论 脑梗死患者血小板GPⅠbα基因Kozak位点存在多态性,HPA-2位点未发现多态性。GPⅠbα基因Kozak位点多态性可能通过影响血小板的活化参与脑梗死的发生过程。     

Glycoprotein Ib polymorphisms influence platelet plug formation under high shear rates

Platelet polymorphisms (Kozak, VNTR and HPA-2) within glycoprotein (GP)Ib alpha may be associated with an increased risk of arterial thrombosis. However, the functional role of these polymorphisms has not been clarified. Their influence on platelet plug formation under high shear rates was, therefore, examined in 233 healthy individuals. Collagen-adrenaline-induced closure time was shorter in carriers of the C/D versus C/C VNTR allele and in homozygotes with the (-5)T/T versus (-5)C/T Kozak genotype as determined by novel polymerase chain reaction methods. The HPA-2 genotype had no effects, and the density of GPIb alpha molecules was not influenced by GPIb alpha genotypes.     

血小板膜糖蛋白Ⅰa和Ⅰbα基因多态性与脑梗死的相关性研究

目的探讨血小板膜糖蛋白(GP)Ⅰa基因和Ⅰbα基因多态性与脑梗死发生的关系,为缺血性脑卒中的预防及治疗提供理论基础。方法选择经CT或MRI证实的脑梗死患者302例(脑梗死组)和健康体检者196例(对照组);采用PCR-RFLP方法检测GPⅠa C807T基因与Ⅰbα基因HPA-2、Kozak序列多态性在2组中的分布频率。结果脑梗死组GPⅠa C807T等位基因频率明显高于对照组,差异有统计学意义(P0.05);脑梗死组GPⅠbα基因Kozak序列C等位基因频率明显高于对照组差异有统计学意义(25.33% vs 10.20%,P0.05);脑梗死组GPⅠbα基因HPA-2序列等位基因频率、基因型与对照组比较,差异无统计学意义(P0.05)。结论 GⅠbα基因HPA-2序列多态性与脑梗死无相关性;GPⅠa C807T等位基因和Ⅰbα基因Kozak序列多态性可能是脑梗死的遗传危险因素。     

A novel isoform of platelet glycoprotein Ibα is prevalent in African Americans

The heavy chain of platelet glycoprotein Ib (GPIb) contains two prevalent sequence polymorphisms. The first, Thr/Met¹⁴⁵ is responsible for the human platelet alloantigen system, human platelet antigen (HPA)-2. The second is a tandem repeat polymorphism that consists of four variants, A, B, C, and D. Previous linkage studies in Caucasian and Eastern Asian populations have demonstrated that HPA-2a (Thr¹⁴⁵) is associated with variants C and D, while HPA-2b (Met¹⁴⁵) is associated with variants A and B. We have determined HPA-2 and variable number of tandem repeats (VNTR) genotypes in three different North American ethnic groups. The gene frequency of HPA-2b in the North American Indians was intermediate between African Americans and Caucasians, and similar to the frequency previously reported in Japanese. Furthermore, the VNTR-A allele, which previously has been reported only in Eastern Asian populations, was present in two of 101 North American Indian individuals. These data are consistent with the hypothesis that the first Native Americans migrated to North America from Eastern Asia. Analysis of HPA-2 and VNTR haplotypes demonstrated an unexpected linkage pattern in the African American population. A rare GPIbα isoform, HPA-2b/VNTR-C, was present in 2.2% of African American haplotypes. Furthermore, a novel GPIbα isoform, HPA-2a/VNTR-B, was present in 6.5% of African American haplotypes. These data suggest a more complex evolutionary pattern of GPIbα isoforms than previously proposed. Am. J. Hematol. 60:77–79, 1999. © 1999 Wiley-Liss, Inc.     

Platelet functional implications of glycoprotein Ibalpha polymorphisms in African Americans

The platelet glycoprotein Ibalpha is crucial in the binding of platelets to Von Willebrand Factor within areas of high stress. A single nucleotide polymorphism of GP Ibalpha gives rise to the Ko(a) (HPA-2b) and the -5C Kozak polymorphism. The presence of these polymorphisms has been associated with an increased risk for atherothrombotic disease. The Ko(a) polymorphism has been shown to have a higher prevalence in African Americans compared to American Caucasians. However, very little is known regarding any functional consequences of these platelet polymorphisms in African Americans. We assessed the prevalence of the Ko and -5C Kozak polymorphisms in a population of both African American and American Caucasian patients with and without CAD and determined whether there were platelet functional consequences in both groups. We studied 99 patients of which 22 were African American and 77 were American Caucasian. Aggregations were performed and shear induced platelet plug formation was tested using a platelet function analyzer. The HPA-2b allele was significantly higher in African Americans when compared to Caucasians (P = 0.001). Genotype frequencies of the -5C Kozak polymorphism were not significantly different between the two groups. We found no differences in platelet aggregation in African Americans who were either heterozygous or homozygous for the HPA-2b allele or the -5C Kozak allele when compared to American Caucasians of the same category. We found no significant differences in PFA-100 testing. We conclude from our study that these polymorphisms do not lead to altered platelet function in African Americans.     

Polymorphisms of platelet glycoproteins in relation to macrovascular disease in Type 2 diabetes mellitus

We set out to determine the genotype distributions of the PI^A polymorphism of platelet glycoprotein IIIa, the HPA-3 polymorphism of platelet glycoprotein IIb, and the variable number tandem repeat (VNTR) polymorphism of platelet glycoprotein Ib in subjects with Type 2 diabetes mellitus (Type 2 DM) with (n = 125) and without (n = 90) a clinical history of macrovascular disease. In 215 white European subjects with Type 2 DM, presence of coronary artery disease was determined as a clinical history of angina, myocardial infarction (MI), coronary angioplasty or coronary artery by-pass grafting. Presence of peripheral vascular disease was defined as a clinical history of intermittent claudication with confirmatory vascular ultrasound or angiography, intermittent claudication with undetectable foot pulses and no history of arthralgia or surgery for leg ischaemia, confirmed by reference to medical case notes. Polymorphisms were detected by polymerase chain reaction amplification of DNA. There was no difference in the genotype distributions of subjects with and without macrovascular disease. In subjects with a first MI before the age of 60 years (n = 26), there was a 38 % incidence of PI^A2 compared to 29 % in subjects free from clinically evident macrovascular disease, but this difference did not reach statistical significance. This study does not support the hypothesis that polymorphisms of platelet glycoproteins, in particular the PI^A polymorphism of platelet glycoprotein IIIa, play an important role in the pathogenesis of macrovascular disease in subjects with Type 2 DM. © 1998 John Wiley & Sons, Ltd.     

Role of 4 platelet membrane glycoprotein polymorphisms on experimental arterial thrombus formation in men.

This study investigates whether the polymorphisms of 3 important platelet receptors affected experimental thrombus formation in men. Forty healthy male volunteers randomly recruited were genotyped for the variable number of tandem repeat (VNTR) of GPIbalpha, the -5T/C polymorphism in the Kozak sequence of GPIbalpha, the 807C/T polymorphism of GPIa, and the PI(A1)/PI(A2) polymorphism of GPIIb/IIIa. Platelet thrombus formation was induced ex vivo by exposing a collagen-coated coverslip in a parallel plate perfusion chamber to native blood for 4 minutes. The shear rates at the collagen surface were 650 and 2600 x s(-1). At 2600 x s(-1) platelet thrombus formation was significantly related only to the 807C/T polymorphism. In contrast, at 650 x s(-1) thrombus formation was significantly altered only by the Kozak sequence polymorphism. The VNTR and the PI(A1)/PI(A2) polymorphisms did not influence thrombus formation. Thus, platelet thrombus formation is significantly influenced by genetic variations of the GPIbalpha and GPIa receptors. The effect of these polymorphisms was dependent on the blood flow rate.     

New alleles of the platelet glycoprotein Ibα gene

Platelet membrane glycoprotein Ibα (GP Ibα) bears two molecular polymorphisms which are in linkage disequilibrium: the C/T dimorphism at codon 145 (HPA-2) and the variable number of tandem repeats (VNTR) polymorphism in the macroglycopeptide region. The frequencies of these two polymorphisms, and of another three recently described silent polymorphisms, were investigated by genotypic identification in 729 Caucasian individuals from the south of Spain. Eight different alleles of this gene, including the longest VNTR A allele of the GP Ibα gene, were found in this population. Moreover, we detected an unexpected linkage between the B and A variants of the VNTR polymorphism and the HPA-2a allele in 5.9% of this population. These results suggest a new evolutionary model of GP Ibα, in which homologous recombination could account for the genetic diversity of the GP Ibα.     

Platelet glycoprotein Ia 807C/T (Phe224) and 873G/A (Thr246) dimorphisms in Turkey

At sites of vascular injury, the platelet collagen receptor Glycoprotein Ia/IIa (GPIa/IIa) acts as an important mediator of platelet adhesion to fibrillar collagens. Two silent polymorphisms (807C/T and 873G/A) within the glycoprotein Ia gene have been implicated in increased risk of developing thrombosis and myocardial infarction in affected individuals. To provide basis for future studies, we examined the frequency of these GPIa polymorphisms for people in Turkey. We analyzed 118 unrelated individuals for their genotypes of the GPIa gene using a multiplexed allele specific-PCR based method. The allelic frequencies were found to be 34% for 807T/873A and 66% for 807C/873G; the genotypic frequencies were 13% for 807TT/873AA, 44% for 807CT/873GA, and 43% for 807CC/873GG.     

Polymorphisms of platelet membrane glycoprotein Ib alpha and plasma von Willebrand factor antigen in coronary artery disease.

To examine the relationships of two polymorphisms of platelet glycoprotein (GP) Ib alpha and coronary artery diseases (CAD) in Japanese patients, we conducted a case-control study with 158 Japanese patients and 169 control subjects. The frequencies of HPA-2 polymorphism and the variable number of tandem repeat (VNTR) polymorphisms in the macroglycopeptide region did not significantly differ between CAD patients and control subjects. The polymorphisms of GPIb alpha were not associated with the number of affected vessels in CAD patients. When patients with acute coronary syndrome only were analyzed, the frequencies of the two polymorphisms of GPIb alpha showed no significant difference. Although plasma von Willebrand antigen (vWF:Ag) levels in patients were significantly higher than in controls, no association between vWF concentration and GPIb genotypes was observed. In patient groups with higher or lower vWF:Ag concentrations, no increase in the frequencies of Met145 or larger VNTR polymorphisms was seen in either group. Our findings indicate that no association exists between the frequencies of the two polymorphisms of GPIb alpha and CAD.     

Genetic variability of platelet glycoprotein Ibalpha gene

Platelet membrane glycoprotein (GP) Ibalpha is a critical component of platelet adhesion complex to subendothelium structures following tissue injury or pathological surfaces, such as atherosclerotic plaques. Polymorphisms of the GPIbalpha gene have been associated with a high risk for occlusive vascular disease, and its distribution varies considerably among distinct populations. These polymorphisms comprise the human platelet antigen (HPA)-2 system, the -5C/T dimorphism of the Kozak sequence, and the variable number of tandem 39-bp repeats (VNTR). Here we report the prevalence of the GPIbalpha gene polymorphisms among Brazilians, a highly ethnically diverse population. We analyzed 492 subjects of European, African, or Indigenous origin. It was possible to determine ten distinct haplotypes. The most common ( reverse similar 40%) haplotype was the Kozak-TT/HPA-2aa/VNTR-CC for both Caucasian and African descent. However, among Indigenous, Kozak-TT/HPA-2aa/VNTR-CC and Kozak-TC/HPA-2aa/VNTR-CC were equally present. Although a strong linkage disequilibrium between VNTR and HPA-2 polymorphism had also been observed, here we determined incomplete linkage disequilibrium in 10% of subjects from all ethnic groups. VNTR-E, a rare variant lacking the 39-bp repeat, was identified in two unrelated subjects, and functional platelet studies revealed no abnormalities. The VNTR-A allele, the largest variant containing four copies of the repeats, was not identified in this population. However, homozygosity for the VNTR-A allele (Kozak-TT/HPA-2aa/VNTR-AA) was determined in two distinct species of nonhuman primates. These results suggest a greater complex evolutionary mechanism in the macroglycoprotein region of the GPIbalpha gene and may be useful in the design of gene-disease association studies for vascular disease.     

Iron deficiency anaemia in young women

OBJECTIVES: The expression density of GPIaIIa, the primary platelet collagen receptor (integrin alpha2beta1), is linked to two polymorphisms (GPIa-807C/T and HPA-5a/b). During evolution a gene shift from the genotypes GPIa-807CC-HPA-5bb to the genotypes GPIa-807CT-HPA-5aa has taken place. The aim of the study was to assess whether iron deficiency anaemia (e.g. increased blood loss) in young women could be associated with a specific genotype, indicating a role as potential evolutionary selection factor. STUDY DESIGN: Women between 18 and 40 yr of age presenting for their first blood donation were asked about alimentary habits and use of oral contraception. Haemoglobin and serum ferritin were measured and the GPIa-C807T and HPA-5 genotypes were determined. RESULTS: Two hundred women were included and grouped according to the WHO definition for iron deficiency anaemia (haemoglobin <121 g L(-1) and ferritin <15 microg L(-1)). Eight women fulfilled both WHO-criteria for iron deficiency anaemia, 145 women fulfilled none. No differences regarding age, use of oral contraceptives, alimentary habits, and HPA-5 were found between the groups. The GPIa-807CC genotype was strongly over-represented in the WHO-anaemic women as compared to the non-WHO-anaemic women (87.5% vs. 33.1%, P=0.003). CONCLUSION: Iron deficiency anaemia in young women might have been the evolutionary disadvantage causing the gene shift from GPIa-807CC to 807CT.     

Platelet receptor HPA-1 polymorphism of alphaIIbbeta3 and 807 C/T polymorphism of alpha2beta1 and Buerger's disease

Thromboangiitis obliterans or Buerger's disease is an episodic and segmental inflammatory and thrombotic process of the medium and small arteries of the lower extremities. Even though the disease was described 90 years ago, the etiopathogenesis is still under consideration. Afflicted patients are mostly young male cigarette smokers without signs of atherosclerosis or other risk factors for peripheral arterial occlusive disease. This indicates that hereditary thrombophilic factors could play a role in the etiopathogenesis. Recently, increasing evidence shows that platelet receptor polymorphisms (HPA-1 polymorphism of beta3 subunit of alphaIIbbeta3 and 807 C/T polymorphism alpha2beta1) are associated with early onset of arterial thrombosis (myocardial infarction, stroke). This case-control study was designed to assess whether the 807 C/T polymorphism or the HPA-1 polymorphism is involved in the pathogenesis of Buerger's disease or has any influence on the clinical course of Buerger's disease. Eighteen patients with Buerger's disease and 81 (sex and age matched) healthy control subjects (mean age 44 +/- 10 vs 45 +/- 8 years, respectively) were genotyped for platelet receptor HPA-1 and GPIa 807 C/T polymorphism. The gene frequency of HPA-1 and GPIa 807 C/T polymorphisms was identical in both groups. Prevalence of hetero- and homozygous carriers of the HPA-1b allel (1a1b and 1b1b genotype) as well as the prevalence of the 807 C/T and 807 T/T carriers did not differ significantly between the two groups, p >0.05. The grade of clinical disease manifestation as well as disease progression did not reveal any significant relationship with HPA-1 and 807 C/T polymorphisms. A relationship between the age at onset of the disease and HPA-1 polymorphism was not found. Otherwise analysis of the GPIa 807 C/T platelet receptor polymorphism showed that the average age of patients who are carriers of the T allele at early onset of disease was 32 +/- 6 years (range 27-48 years) compared to 42 +/- 6 years (range 34-53 years) of the C/C carriers (p <0.05). This indicates that the GPIa 807 C/T polymorphism does not represent a risk factor for Buerger's disease itself, but could be associated with premature onset of this disorder in predisposed individuals.     

血小板膜糖蛋白Ⅰb Kozak序列-5T/C及纤维蛋白原β-148C/T基因多态性与脑梗死

目的研究雷州半岛地区汉族人群血小板膜糖蛋白(GP)ⅠbKozak序列-5T/C和纤维蛋白原(Fib)β-148C/T基因多态性位点与脑梗死的关系。方法选择雷州半岛地区汉族人群健康体检者130例(对照组)和经头颅CT和(或)MRI证实的脑梗死患者148例(脑梗死组),用PCR-RFLP检测GPⅠbKozak序列-5T/C和Fibβ-148C/T基因多态性,分析两组频率分布特点及与脑梗死的关系。结果脑梗死组β-148C/T位点T等位基因频率为30.1%,对照组为21.9%,(P<0.05),脑梗死组GPⅠbKozak序列C等位基因频率为48.7%,对照组为39.6%,(P<0.05),两个多态性位点连锁不平衡系数D为-0.018(P>0.05)。结论Fibβ-148C/T位点T等位基因和GPⅠbKozak序列C等位基因是雷州半岛地区汉族人群脑梗死的遗传易感因素,但二者不存在连锁不平衡关系。     

Polymorphism of the human platelet antigen-5 system is a risk factor for occlusive vascular complications in patients with sickle cell anemia

BACKGROUND: Polymorphisms of platelet membrane glycoproteins such as human platelet antigen (HPA)-1b, HPA-2b, the -5T/C Kozak sequence and C807T have been described as risk factors for vascular disease. Vaso-occlusion episodes are a common feature of sickle cell anaemia (SCA), leading to complications such as stroke, acute chest syndrome, avascular head femur necrosis and priapism. Complex interactions are involved in vaso-occlusion, and activated platelets may play an important role. These data raised the question of whether platelet polymorphisms could be implicated in occlusive vascular complications (OVC) of SCA. MATERIALS AND METHODS: In this study, 97 patients with SCA were analysed in two groups: 34 patients presenting with OVC (SCA-VC) and 63 without these complications (SCA-N). The distribution of the HPA-1, -2 and -5 systems, as well as C807T dimorphism and -5T/C Kozak sequence alleles, was evaluated using DNA-based methods. RESULTS: Patients of the SCA-VC group showed a higher frequency of the HPA-5b allele (0.324) compared with those of the SCA-N group (0.111) (chi2 = 13.19, P = 0.0002). None of the other polymorphisms, isolated or associated as haplotypes, demonstrated any correlation with the development of OVC in these patients. CONCLUSIONS: The findings of this study suggest that the HPA-5b allele is a genetic risk factor for the development of OVC in patients with SCA. This allele could be explored as a target for the development of new therapeutic approaches.     

汉族人血小板GPⅠbHPA-2基因多态性与冠心病血瘀证的相关性研究

目的 观察GPⅠbHPA-2（Ko^b／Ko^a）基因多态性，在北京河北地区汉族人中各基因型的分布频率，分析该多态性与冠心病、冠心病血瘀证易感性的相关性。方法 采用病例对照设计，筛选符合冠心病、血瘀证、健康人入选标准的110例冠心病血瘀证、102例冠心病非血瘀证患者及106例健康对照人群为研究对象，进行中医辨证分型、血瘀证计分，并记录冠脉造影病变支数，采用基因测序技术检测HPA-2基因多态性。结果 GPⅠbHPA-2a／2a、HPA-2a／2b、HPA-2b／2b各占90．9％，8．8％和0．3％，所有入选病例中仅有1例表达HPA-2b／2b型；冠心病组和健康对照组、冠心病血瘀证组和冠心病非血瘀证组的基因型构成，冠心病患者不同病变支数基因型构成，冠心病血瘀证各基因型患者的血瘀证计分，各组间比较均无显著性差异（P〉0．05）。以是否患冠心病为因变量的二分类Binary Logistic回归分析，校正年龄、性别、体重指数对冠心病的影响后，结果显示HPA-2多态位点基因型与冠心病发病无相关性。结论 GPⅠb的HPA-2多态位点不是汉族人冠心病、冠心病血瘀证的独立危险因素。     

Platelet glycoprotein Ia 807C/T and 873G/A polymorphisms in patients with venous thromboembolism.

Two silent polymorphisms (807C/T and 873G/A) within glycoprotein Ia (GPIa) gene have been implicated in increased risk of developing thrombosis and myocardial infarction in affected individuals. The aim of this study was to investigate the GPIa gene polymorphism in patients with venous thromboembolism (VTE). A multiplexed allele specific-polymerase chain reaction (AS-PCR)-based method was used to determine the GPIa 807T/873A allele frequency in 77 patients with VTE and 106 healthy controls. The allelic frequency for 807T/873A was 33% in the patient group and 38% in the control group. The allelic frequency for 807C/873G was 66% in the patient group and 62% in the control group. The genotypic frequencies were 8% for 807TT/873AA, 42% for 807CC/GG, and 50% for 807CT/GA in the patient group. In the control group, the frequencies were 12% for 807TT/873AA, 35% for 807CC/873GG, and 52% for 807CT/873GA. As a result, the glycoprotein Ia 807C/T and 873G/A dimorphisms were not shown as risk factors for VTE.     

Gene frequencies of the human platelet antigen-3 in different populations.

Human platelet antigen (HPA) systems consist of more than 12 biallelic antigen polymorphisms in which a base pair substitution leads to change in an amino acid of a glycoprotein expressed on the platelet. HPA-3 is a HPA that is mentioned for possible induction of neonatal alloimmune thrombocytopenia, posttransfusion purpura, and platelet refractoriness. A summary is presented of previous reports on the gene frequencies of HPA-3 among different populations. The frequency of HPA-3a and -3b ranges from 0.50 to 0.61 and 0.38 to 0.50, respectively. A significant correlation between the population ethnicity and the gene frequencies was detected in this study. However, it is quite difficult to use HPA-3 gene as a gene marker to determine the similarity of gene population in different populations. In addition, the comparison of the heterogenicity of HPA-3 frequencies to another well-known HPA gene, HPA-1 gene demonstrates that there is a greater variation in HPA-3 frequencies than in the HPA-1 gene. There was no significant correlation between the incidence of autoimmune thrombocytopenia disorder and the HPA-3 gene polymorphism pattern.