Detection of the Glanzmann's thrombasthenia mutations in Arab and Iraqi-Jewish patients by polymerase chain reaction and restriction analysis of blood or urine samples

Severe Glanzmann's thrombasthenia is relatively frequent in Iraqi-Jews and Arabs residing in Israel. We have recently described the mutations responsible for the disease in Iraqi-Jews--an 11 base pair deletion in exon 12 of the glycoprotein IIIa gene, and in Arabs--a 13 base pair deletion at the AG acceptor splice site of exon 4 on the glycoprotein IIb gene. In this communication we show that the Iraqi-Jewish mutation can be identified directly by polymerase chain reaction and gel electrophoresis. With specially designed oligonucleotide primers encompassing the mutation site, an 80 base pair segment amplified in healthy controls was clearly distinguished from the 69 base pair segment produced in patients. Patients from 11 unrelated Iraqi-Jewish families had the same mutation. The Arab mutation was identified by first amplifying a DNA segment consisting of 312 base pairs in controls and of 299 base pairs in patients, and then digestion by a restriction enzyme Stu-1, which recognizes a site that is absent in the mutant gene. In controls the 312 bp segment was digested into 235 and 77 bp fragments, while in patients there was no change in the size of the amplified 299 bp segment. The mutation was found in patients from 3 out of 5 unrelated Arab families. Both Iraqi-Jewish and Arab mutations were detectable in DNA extracted from blood and urine samples. The described simple methods of identifying the mutations should be useful for detection of the numerous potential carriers among the affected kindreds and for prenatal diagnosis using DNA extracted from chorionic villi samples.

[Flow cytometric analysis of platelets in patients with Glanzmann's thrombasthenia]

Platelets from 10 patients with Glanzmann's thrombasthenia (7 patients with type I and 3 with type II) and their 18 family members (11 parents, 6 siblings and one daughter) were analyzed by flow cytometry using 3 different commercially available FITC-labeled monoclonal antibodies. The amount of platelet GPIIbIIIa was calculated by using the ratio of the fluorescence intensity of the mean channel in comparison to normal platelets. The amount of platelet GPIIbIIIa was lower than 19% in 6 patients with type I and one patient with type II thrombasthenia. One type I patient had a 46.5% GPIIbIIIa amount as assessed using the monoclonal antibody TP80 (Nichirei Corp. Japan) which recognized GPIIb, although the other 2 antibodies showed an amount of less than 5%. One type II patient showed the following results: 30.9% (TP80), 28.2% (P2 antibody, Immunotech, France), and 3.9% (PLT1, Coulter Immunology, USA). The remaining type II patient consistently showed a normal amount of platelet GPIIbIIIa using all antibodies, appeared to be a variant form of thrombasthenia. The parents of type I patients had a significantly lower amount of platelet GPIIbIIIa compared to normal and 2 siblings of type I patients were diagnosed as heterozygotes. These findings suggest that Glanzmann's thrombasthenia is more heterogeneous than we have previously suspected, and that flow cytometric analysis using different monoclonal antibodies is a useful tool for identifying those heterogeneities and for the detection of type I carriers.

A variant form of thrombasthenia

We encountered two siblings with abnormal bruising since infancy. Studies revealed functional platelet defects characterized by a lack of platelet aggregation and adenosine triphosphate release on exposure to adenosine diphosphate and collagen as well as variable responses with ristocetin (at concentrations of less than or equal to 1.25 g/L) and arachidonic acid. In addition, little or no platelet aggregation was observed after exposure to hexadimethrine bromide (Polybrene), the calcium ionophore A23187, and the thromboxane/endoperoxide analogue U46619. The membrane proteins IIIa and Ib were present, as determined with monoclonal antibody testing, and no platelet-associated IgG was found. Platelet analysis with routine electron microscopy and ultrastructural cytochemistry revealed normal morphologic features and no deficiencies in the number of alpha granules dense bodies and other organelles. The platelet abnormality may represent a new variant of thrombasthenia.

The molecular genetic basis of Glanzmann thrombasthenia in the Iraqi-Jewish and Arab populations in Israel

Glanzmann thrombasthenia is an autosomal recessive bleeding disorder characterized by a decrease or absence of functional platelet glycoprotein (GP) IIb-IIIa (alpha IIb beta 3) integrin receptors. Although thrombasthenia is a rare disorder, its occurrence is increased in some regions of the world where intracommunity marriage and consanguinity are commonplace, resulting in increased expression of autosomal recessive traits. We have been studying two populations having an unusually high frequency of Glanzmann disease, Iraqi Jews and Arabs living in Israel, and were able to distinguish the populations on the basis of immunodetectable GPIIIa and platelet surface vitronectin receptor (alpha v beta 3) expression. In this article, we describe molecular genetic studies based on use of the PCR that have allowed us to characterize platelet mRNA sequences encoding GPIIb and GPIIIa from patients in these populations. In six of six Iraqi-Jewish families studied, cDNA sequence analysis identified an 11-base deletion within exon 12 of the GPIIIa gene. This mutation produces a frameshift leading to protein termination shortly before the transmembrane domain of GPIIIa. In contrast, a 13-base deletion encompassing the splice acceptor site of exon 4 of the GPIIb gene was found in three of five Arab kindreds studied. This deletion results in forced alternative splicing to a downstream AG acceptor, producing a 6-amino acid deletion in the GPIIb protein, including a single cysteine residue. These nucleotide sequence variations were exploited to design a rapid, PCR-based oligonucleotide dot-blot hybridization test for both pre- and postnatal diagnosis of Glanzmann disease. These studies demonstrate the heterogeneity of Glanzmann thrombasthenia in different populations, and its homogeneity within geographically restricted populations, and offer insight into the requirements for integrin surface expression.

A deletion in the gene for glycoprotein IIb associated with Glanzmann's thrombasthenia

The platelet fibrinogen receptor is composed of a complex of glycoproteins (GP) IIb and IIIa on the surface of platelets. Deficient function of this receptor prevents normal platelet aggregation, resulting in Glanzmann's thrombasthenia (GT). In this paper, we describe a black thrombasthenic patient who is either homozygous or hemizygous for a deletion within the GPIIb gene. Initial Western blot analysis of platelet proteins from this patient did not detect any GPIIb, but did detect small amounts of GPIIIa of normal mobility. Quantitation of vitronectin receptor (VNR) demonstrated that this thrombasthenic patient had approximately 1.5-2 times the number of these receptors per platelet compared with controls, a finding that has previously been noted in other thrombasthenic patients with defects in GPIIb. Genomic Southern blot studies demonstrated a deletion in the GPIIb gene of approximately 4.5 kilobasepairs (kb). Analysis of the isolated GPIIb gene demonstrated that the deletion begins between two Alu repeats within intron 1 and ends in intron 9. Polymerase chain reaction (PCR) studies using platelet RNA and oligonucleotides directed to both the 5' and 3' ends of the GPIIb cDNA sequence easily detected GPIIb transcript, suggesting that the genomic deletion of exons 2-9 does not significantly decrease the level of the GPIIb mRNA. Sequence analysis of PCR-generated GPIIb cDNA showed that a cryptic AG splice acceptor sequence was being utilized, resulting in a transcript that contained a portion of introns 1 and 9, as well as having a deletion of exons 2-9. Unlike the GPIIb gene, the GPIIIa gene appears to be intact by Southern blot analysis. PCR studies using platelet RNA and oligonucleotides directed to the GPIIIa cDNA sequence demonstrated the presence of GPIIIa mRNA. In summary, the thrombasthenic state in this patient appears to be due to a GPIIb gene deletion resulting in an abnormal transcript and no detectable platelet GPIIb. Platelet GPIIIa levels were secondarily low presumably due to the known instability of GPIIIa in the absence of GPIIb.

[Glanzmann thrombasthenia--a defect in the surface membrane of platelets]

The authors present a clinical description, detailed platelet function analysis, and certain biochemical parameters in two siblings with Glanzmann thrombasthenia (G. t.). The isolated occurrence of this disorder in the family corresponds with its autosomal recessive inheritance. In both cases blood platelets completely failed to aggregate. In contrast, the platelet interaction with ristocetin, reflecting their ability to adhere to the subendothelium, the so-called "shape change", the storage granule contents and their release and arachidonic acid metabolism were unaffected. Further, the aggregation abnormality was accompanied by marked procoagulant activity and clot retraction defects; these functions, similarly as aggregation, are implemented on the platelet surface. The analysis of blood platelet proteins, using two dimensional polyacrylamide electrophoresis, confirmed the absence of glycoprotein GP IIb and IIIa and a decrease of the fibrinogen content. The analysis of these findings in G. t. led to the contemporary concept that GP IIb and IIIa on the platelet surface act as receptors for platelet aggregation.

Identification of an abnormal gene for the GPIIIa subunit of the platelet fibrinogen receptor resulting in Glanzmann's thrombasthenia

The platelet fibrinogen receptor, which is composed of glycoproteins IIb (GPIIb) and IIIa (GPIIIa), belongs to a large family of receptors that participate in a multitude of biologically important adhesive interactions. Platelets from most patients with the autosomal recessive bleeding disorder, Glanzmann's thrombasthenia, are deficient in GPIIb and GPIIIa. We have used cDNA probes to analyze the GPIIb and GPIIIa genes in four patients from three kindreds with Glanzmann's thrombasthenia. Southern analysis of their DNA was identical to that observed in normals when probed with a full-length GPIIb cDNA or a 3' GPIIIa cDNA. However, in one family, a 5' 2.0 kb GPIIIa cDNA identified abnormal DNA fragments in the father and two affected siblings' genes. A series of restriction digests resulting in small genomic fragments were probed with portions of the 5' 2.0 kb GPIIIa cDNA and indicated that the abnormal sequences are flanked by normal fragments of the GPIIIa gene. To analyze further the genetic defect in this family, RNA was prepared from their platelets. Northern analysis revealed normal levels of GPIIb mRNA compared to control platelets. We were unable to identify GPIIIa mRNA of any size in the clinically affected family members. We also identified an EcoRI restriction fragment length polymorphism (RFLP) that permitted carrier status determination in the clinically unaffected siblings. These studies indicate that Glanzmann's thrombasthenia can be caused by heterogeneous defects in the GPIIIa gene. Furthermore, we have shown that platelets can be used to characterize normal and abnormal GPIIIa and GPIIb mRNA, and RFLPs may be used to determine the carrier status in some families with Glanzmann's thrombasthenia. The specific gene abnormality in this family appears to represent an example of an insertional mutation resulting in a human disease.

The use of fluorescence flow cytometry in the characterization of Bernard-Soulier syndrome and Glanzmann's thrombasthenia

We have used flow cytometry analysis of fluorescence to study the binding of murine monoclonal antibodies to platelets. Anti-platelet glycoproteins Ib (AP1), the complex IIb-IIIa (LJP9) and the FITC-conjugated second antibody were added directly to the sample of platelet rich plasma without washing. The analysis was performed in normals and in patients affected by the Bernard-Soulier syndrome and Glanzmann's thrombasthenia and compared to the direct binding of radioiodinated monoclonas. Comparable results were obtained. A symmetric profile of fluorescence for both glycoproteins Ib and IIb-IIIa was observed in normals and in the patient group, which indicates homogeneous distribution of these glycoproteins on the platelet surface. The develop technique allows identification of homozygous and heterozygous carriers of the platelet disorders studied and quantification of the defect, which seems to be due to a homogeneous decrease of specific glycoproteins in all platelet populations.

Structural integrity of the glycoprotein IIb and IIIa genes in Glanzmann thrombasthenia patients from Israel

Glanzmann thrombasthenia is an autosomal recessive disorder of the platelet glycoproteins (GP) IIb and IIIa. These glycoproteins normally serve as receptors for other adhesive glycoproteins, including fibrinogen, von Willebrand factor, and fibronectin. Most patients affected by Glanzmann thrombasthenia have low levels of GPIIb and GPIIIa; however, the separate mechanisms responsible for the deficiency in each remain to be determined. cDNA clones coding for the GPIIb and GPIIIa have been recently isolated, and their corresponding genomic sequences have been colocalized to the long arm of chromosome 17. Since a deletional event involving one or both of these structural genes could explain the disease phenotype, we have studied the DNA of two previously well-characterized cohorts of Glanzmann thrombasthenia patients from Israel. We performed Southern analysis with near full-length cDNA probes on genomic DNA obtained from 20 individuals. Four restriction enzyme digests were completed on each DNA sample. The similarity of banding patterns among probands, family members, and controls indicated that there were no major insertions or deletions in either the GPIIb or GPIIIa genes. Thus, the genetic defect in these patients with Glanzmann thrombasthenia is most likely due to either a small change in the nucleotide sequence of the coding region or a defect in the regulatory region of one or both genes.

Thrombasthenia with an abnormal platelet membrane glycoprotein IIb of different molecular weight

We describe an individual with abnormal platelet glycoprotein (GP) IIb of different molecular weight (mol wt), a defect that distinguishes this patient from previously reported thrombasthenics. The patient, a 21-year-old female, has a mild bleeding tendency; her platelets lack adenosine diphosphate (ADP) aggregation and have severely suppressed collagen aggregation but a normal response to ristocetin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of her platelets indicates that they contain two types of GPIIb molecules: one with an abnormal mol wt (122 kd, unreduced; 128 kd, reduced) and one with a normal mol wt (128 kd, unreduced; 118 kd, reduced). Relative to the amount of GPIIb in normal platelets, her platelets contain approximately 35% abnormal GPIIb and 20% normal GPIIb. Fibrinogen binding assays on the patient's platelets indicated that they contained 25% of the normal amount of fibrinogen receptors. Crossed immunoelectrophoresis of the patient's platelets demonstrated the formation of a GPIIb/IIIa complex that was mainly composed of normal mol wt GPIIb and GPIIIa. The patient's father has decreased ADP aggregability, and his platelets also contained both abnormal and normal GPIIb (about 50% of the normal level and about 50% of the normal number of fibrinogen receptors); her mother has only normal GPIIb. These results indicate that the patient has heterozygous GPIIb molecules with an abnormality of GPIIb at the molecular level. Studies on this abnormal GPIIb should provide information about the function of GPIIb and the mechanism of its biosynthesis.

Normal synthesis and expression of endothelial IIb/IIIa in Glanzmann's thrombasthenia

Glanzmann's thrombasthenia is a bleeding disorder, inherited in an autosomal recessive way and characterized by an absence or deficiency of the platelet glycoprotein (GP) IIb/IIIa complex. Recently, we and others demonstrated that cultured human umbilical vein endothelial cells synthesized a membrane protein complex similar to the platelet GP IIb/IIIa complex. In this article, we demonstrate that endothelial cells isolated from the umbilical vein of a newborn with Glanzmann's thrombasthenia, as compared with normal endothelial cells, show no difference in their ability to synthesize and express this GP IIb/IIIa complex. Our results indicate that Glanzmann's thrombasthenia is not accompanied by an "endotheliopathy."

Inherited abnormalities of the platelet membrane and secretory granules

Platelet stimulus-activation-contraction-secretion coupling is linked to fundamental modifications in the biochemistry and ultrastructure of the platelet surface and the membranes enclosing storage organelles. It is not surprising, therefore, that membrane defects are common in platelets from patients with inherited hemorrhagic disorders caused by platelet dysfunction. In fact, it might be stated that all inherited disorders of platelet function are related directly or indirectly to abnormalities of membranes. The current review discusses the state of knowledge on inherited platelet membrane defects of the cell surface and storage organelles.

Probable autosomal recessive syndrome with triphalangia of thumbs, thrombasthenia Glanzmann and deafness of internal ear

A 22-year-old woman is described who presented with triphalangeal thumbs, Glanzmann's thrombasthenia and deafness of internal ear. These are features of a probable genetically determined syndrome, which can be differentiated from other radial defect syndromes. Like in typical Glanzmann's thrombasthenia, our patient showed severely reduced concentrations of glycoprotein IIb-IIIa. The patient's parents revealed reduced concentrations of glycoprotein IIb-IIIa and were considered to be heterozygotes. Thus autosomal recessive inheritance of the bleeding disorder was demonstrated. As a consequence we suppose that the complete syndrome follows this way of inheritance.

Two-dimensional electrophoretic studies of platelets from dogs affected with basset hound hereditary thrombopathy: a thrombasthenia-like aggregation defect

Because of a thrombasthenia-like platelet aggregation defect, platelets from dogs affected with Basset Hound Hereditary Thrombopathy were compared to normal control dog platelets by three different techniques in order to assess platelet membrane glycoprotein content. Crossed immunoelectrophoresis (CIE), two-dimensional nonreduced-reduced electrophoresis (NR-R), and O'Farrell two-dimensional electrophoresis were used for the assays. CIE and NR-R gels detected no differences between affected Basset Hound and control dog platelets. Gels run by the O'Farrell technique detected no differences in glycoprotein/protein content, however, there appear to be several constituents missing from BHT affected dog platelet samples. The missing components appear to be either lipids or sialoglycoproteins as they were detectable by silver staining but not by Coomassie Blue staining.