Do we need more guidance on thrombophilia testing? Challenges and special considerations

INTRODUCTION

Thrombophilia testing (TT) is a laboratory procedure designed to detect the risk factors involved in the pathogenesis of vascular occlusions. The role of TT is also controversial because it has a limited impact on the choice and duration of antithrombotic treatments.

AREAS COVERED

We reviewed, by examining MEDLINE up to October 2023. Accepted and not accepted thrombophilia markers are discussed along with the appropriateness or not of prescribing TT in several conditions such as: provoked and unprovoked venous thromboembolism (VTE), women who are planning a pregnancy whose relatives had VTE or have a hereditary thrombophilia, before assumption of estro-progestins, after multiple pregnant loss, arterial thrombosis, retinal vein occlusion, and splanchnic vein thrombosis.

EXPERT OPINION

TT is not essential in the management of VTE, but it may be useful for limiting adverse events in case of thrombophilia. We expose our criticism of items afforded by other guidelines by presenting our opinion based on both the scientific evidence and clinical practice. We also deal with common mistakes in prescribing and interpretations of TT hoping to purpose an educational approach on this topic. Finally, we emphasize the creation of the expert in hemostasis and thrombosis who should be present in every hospital.

Primary Thrombophilia XVII: A Narrative Review of Sticky Platelet Syndrome in México

Sticky Platelet Syndrome (SPS) is a disorder characterized by platelet hyperaggregability, diagnosed by studying in vitro platelet aggregation with ADP and epinephrine. It is the second most common cause of thrombophilia in Mexican Mestizos and manifests as an autosomal dominant trait which, combined with other coagulopathies, contributes significantly to the morbidity and mortality of patients with primary thrombophilia. It is easily treatable with antiplatelet drugs; however, the methods for diagnosis are not readily available in all clinical laboratories and the disorder is often overlooked by most clinicians. Herein, we present the results of more than 20 years of Mexican experience with the study of SPS in a Mestizo population.

Association of Genetic Variability in Selected Genes with Platelet Hyperaggregability and Arterial Thrombosis

Introduction: Inherited platelet hyperaggregability, so called “Sticky platelet syndrome” (SPS), is a prothrombotic platelet disorder. The syndrome contributes more often to arterial than venous thrombosis. The most common localization of arterial occlusion involves cerebral or coronary arteries. However, SPS may also lead to thrombosis in the atypical sites of the circulation. This qualitative platelet alteration causes platelet hyperaggregability after a very low concentration of platelet inducers – adenosine diphosphate (ADP) and/or epinephrine (EPI). The precise genetic background of the syndrome has not been defined. In the present study we aimed to determine the association between selected single nucleotide polymorphisms (SNPs) within genes for platelet endothelial aggregation receptor 1 (PEAR1) and murine retrovirus integration site 1 (MRVI1) and the risk for arterial thrombosis in patients with SPS. The products of these selected genes play an important role in platelet aggregation.

Patients and methods: We examined 69 patients with SPS and a history of arterial thrombosis and 69 healthy blood donors who served as controls. SPS was confirmed by a light transmission aggregometry (LTA) according to the method and criteria described by Mammen and Bick. We assessed two SNPs within PEAR1 gene (rs12041331, rs1256888) and two SNPs within MRVI1 gene (rs1874445, rs7940646).

Results: Selected PEAR1 and MRVI1 polymorphisms seem not to be a risk factor for the development of SPS as the syndrome with an arterial thrombosis phenotype. However, in the subgroup of SPS1 patients there was found a decreased frequency of the minor A allele of SNP rs12041331 in PEAR1 gene (borderline p value, p=0.061) that can be hypothesized as protective against arterial thrombosis. In the same SPS1 subgroup the haplotype TA in PEAR1 gene also showed a decreased frequency with a borderline insignificance (p=0.056). We can theorize also about its protective role in SPS1 patients. We did not confirm the protective effect of polymorphism (T/T of rs 12566888) in PEAR1 against arterial thrombosis in SPS patients and SPS subgroups.

Conclusion: Our results support the idea that examined genetic variability of the selected SNPs in PEAR1 and MRVI1 genes is not associated with platelet hyperaggregability manifested as arterial thrombosis. The possible protective role of the minor A allele of SNP rs12041331 as well as a role of haplotype TA in PEAR1 gene related to the arterial thrombosis found in the subgroup of SPS1 patients needs to be verified in further research.

A new decade awaits sticky platelet syndrome: where are we now, how do we manage and what are the complications?

INTRODUCTION

Sticky platelet syndrome is a less known platelet function disorder with a familiar occurrence and likely genetic background. Clinically, it is characterized by an increased risk of venous and arterial thromboembolic events and obstetric placenta-mediated complications. The increased aggregation after low-dose ADP and/or epinephrine is its distinctive laboratory feature. Though described for almost 40 years, several issues regarding its etiology, involved pathomechanisms, genetic background, optimal diagnostic and treatment approach remain controversial.

AREAS COVERED

The work aims to summarize published studies, the actual definition of the syndrome, and point out its drawbacks. A literature search on Medline, Embase, and archives from EHA congresses was performed (terms: 'sticky platelet syndrome' - 'platelet hyperreactivity' - 'platelet hyperaggregability'). The authors added in their unpublished data. The introductory overview of the present understanding is followed by the discussion of the pathophysiologic, diagnostic, and therapeutic problems.

EXPERT OPINION

Despite the growing evidence provided by case reports and series, the lack of robust studies limits the decision-making on diagnostics and management. The diagnostic issues, particularly the standardization of light transmission aggregometry, represent the crucial problem for the broader acceptance of the syndrome.

Primary Thrombophilia XVI: A Look at the Genotype of the Sticky Platelet Syndrome Phenotype

The sticky platelet syndrome (SPS) was described by Mammen in 1983. Since then, scientists in several countries have identified the condition and published cases or series of patients, thus enabling the description of the prevalence of the inherited condition, its salient clinical features, and the treatment of the disease. The diagnosis of the SPS phenotype requires fresh blood samples and special equipment which is not available in all coagulation laboratories. In the era of molecular biology, up to now it has not been possible to define a clear association of the SPS phenotype with a specific molecular marker. Some molecular changes which have been described in platelet proteins in some persons with the phenotype of the SPS are here discussed. Nowadays, the SPS phenotype may be considered as a risk factor for thrombosis and most cases of the SPS developing vaso-occlussive episodes are the result of its coexistence with other thrombosis-prone conditions, some of the inherited and some of them acquired, thus leading to the concept of multifactorial thrombophilia. Ignoring all these evidence-based concepts is inappropriate, same as stating that the SPS is a nonentity simply because not all laboratories are endowed with adequate equipment to support the diagnosis.

Molecular study of sticky platelet syndrome using exome sequencing

Introduction: Sticky platelet syndrome (SPS) is a prothrombotic condition characterized by increased platelet aggregation that causes arterial and venous thrombosis. Its diagnosis is reached by identifying increased aggregation using low concentrations of adenosine diphosphate and epinephrine in platelet aggregation tests. Objectives: To identify common mutations through exome sequencing in two patients from the same family diagnosed with SPS and, thus, contribute to the molecular study of this disease. Materials and methods: Descriptive study. In January 2018, exome sequencing was performed in a 10-year-old patient treated at Fundación HOMI (Bogotá D.C., Colombia), index case, and in one of his adult first-degree relatives, both with a history of thrombotic disease and diagnosed with SPS. Exome sequencing was performed at the Complexo Hospitalario Universitario de Santiago de Compostela (Spain) using the SureSelect Clinical Research Exome V2 software by Agilent. Results: Exome sequencing led to detect genetic variants in both cases when compared with the reference sequence. The following variant was identified in the two samples: a cytosine to thymine transition at position c.236 (NM_000174.4) of the glycoprotein (GP)Ib-IX-V complex platelet membrane receptor, which causes a heterozygous transition of the amino acid threonine to isoleucine (i.e., a transition from hydrophilic amino acid to a hydrophobic amino acid) at position p. 79 of the extracellular leucine-rich repeat domain of GPIbα subunit of the (GP)Ib–IX complex, involving a conformational change of the main receptor of ligands IB alpha, which might result in platelet hyperaggregation and thrombosis. This variant has not been described in patients with SPS to date. Conclusion: The mutation identified in both samples could be related to SPS considering the importance of glycoprotein IX in platelet function.

High Prevalence of Sticky Platelet Syndrome in Patients with Infertility and Pregnancy Loss

Platelet hyperaggregability, known as sticky platelet syndrome (SPS), is a prothrombotic disorder that has been increasingly associated with pregnancy loss. In this retrospective study, we aimed to investigate the clinical and diagnostic relevance of SPS in 208 patients with infertility and unexplained pregnancy loss history. We studied 208 patients that had been referred to undergo a dose-dependent platelet aggregation response to adenosine diphosphate and epinephrine using light transmission aggregometry modified by Mammen during an 11-year period. Patients’ platelet aggregation response was compared with platelet function in 29 female healthy controls of fertile age with no previous history of pregnancy loss. We found a prevalence of SPS type II (33.2%) in 208 female patients with infertility and pregnancy loss. ∆-epinephrine-induced platelet aggregation in patients with SPS was significantly decreased (median 7% and range −21 to 43%) compared to patients without SPS (median 59%, range 7–88% and p < 0.0001) and healthy controls (median 57%, range 8–106% and p < 0.0001). The optimum SPS-diagnostic cutoff value for ∆-epinephrine aggregation was ≤32% (sensitivity 95.7%, specificity 95.2%). SPS patients with low-dose acetylsalicylic acid (ASA) therapy (n = 56) showed improved pregnancy outcome (32 pregnancies; live births n = 18 (56%)) compared to SPS patients without low-dose ASA (n = 13) (3 pregnancies; live births n = 1 (33%)). Our study demonstrates the clinical and diagnostic relevance of platelet hyperaggregation in women with infertility and pregnancy loss history. Further studies should investigate the potential of SPS as a novel decisional tool with both diagnostic and clinical implications in infertility and pregnancy loss.

Primary Thrombophilia in Mexico XIII: Localization of the Thrombotic Events in Mexican Mestizos With the Sticky Platelet Syndrome

The sticky platelet syndrome (SPS) is a common cause of both arterial and venous thrombosis, being a dominant autosomal disease with qualitative platelet alterations and familial occurrence. It is characterized by platelet hyperreactivity with increased platelet aggregability in response to low concentrations of platelet agonists: epinephrine, adenosine diphosphate, or both. The clinical manifestations involve venous or arterial thrombosis, recurrent pregnancy loss, and fetal growth retardation. To analyze the localization of the thrombotic episodes in a cohort of Mexican mestizo patients with SPS. Between 1992 and 2016, 86 Mexican mestizo patients with SPS as the single thrombophilic condition were prospectively identified; all of them had a history of thrombosis. There were 15 males and 71 females. The thrombotic episodes were arterial in 26 cases and venous in 60 (70%). Arterial thrombosis was mainly pulmonary thromboembolism, whereas venous thromboses were identified most frequently in the lower limbs. Mexican mestizo population with SPS is mainly female; the type I of the condition is the most frequent; both arterial and venous thrombosis can occur, and they are mainly pulmonary embolism and lower limbs venous thrombosis, respectively.

Platelet activation by ADP is increased in selected patients with anterior ischemic optic neuropathy or retinal vein occlusion

To investigate whether adenosine diphosphate (ADP)-induced platelet hyperaggregability is associated with nonarteritic anterior ischemic optic neuropathy (NAION) or retinal vein occlusion (RVO). We retrospectively reviewed thrombophilia screening data of patients with NAION or RVO without a history of arterial hypertension, diabetes mellitus, hyperlipidemia, obesity, and cigarette abuse. Patients with a positive family history for thromboembolism were not excluded. Platelet aggregation (area under the curve, AUC) after induction of 0.5, 1.0, and 2.0 µmol of ADP was estimated in 25 NAION and RVO patients and compared with 25 healthy controls. We observed significantly greater platelet aggregation post 0.5 (P = 0.002) and 1.0 (P = 0.008) µmol of ADP among NAION and RVO patients compared with healthy controls. Platelet hyperaggregability was significantly more prevalent in patients than in controls (56% vs. 8%; P = 0.0006). Our results suggest that in NAION and RVO patients without a history of arterial hypertension, diabetes mellitus, hyperlipidemia, obesity, and cigarette abuse, platelets are significantly hyperreactive after induction of very low concentrations of ADP when compared with healthy individuals. This hyperreactivity is particularly evident in patients with a family history of thromboembolism.

Primary Thrombophilia in Mexico XII: Miscarriages Are More Frequent in People with Sticky Platelet Syndrome

Objective:

Sticky platelet syndrome (SPS) is an inherited condition that leads to arterial and venous thrombosis. There is scant information about the association between SPS and obstetric complications. This study aimed to assess the relationship between SPS and fetal loss at a single institution.

Materials and Methods:

The obstetric histories of all consecutive female patients prospectively studied in a 324-month period at a single institution with a history of thrombosis and a clinical marker of primary thrombophilia were reviewed.

Results:

Between 1989 and 2016, 268 consecutive patients with a clinical marker of primary thrombophilia and a history of arterial or venous thrombosis were studied; of these, 108 were female patients. Within this subset of thrombophilic females, 77 (71%) had been pregnant at some point. Twenty-eight of these 77 patients (37%) had had a spontaneous abortion and 24 of those (86%) were found to have SPS. On the other hand, in a subset of 73 female patients with SPS who had been pregnant, 32% had miscarriages. These figures are significantly higher than the prevalence of spontaneous abortions in the general Mexican population of pregnant women, which is 12%-13% (chi-square: 7.47; p=0.0063). Accordingly, the relative risk of having a miscarriage is 2.66 times higher in female patients with SPS than in the general population (p=0.0014).

Conclusion:

In Mexico, female patients with SPS experience significantly more spontaneous abortions than the general population. Since the treatment of SPS is simple and effective and could in turn prevent adverse obstetric outcomes, its investigation in women treated for obstetric complications may be useful and deserves further research.

Sticky platelet syndrome: an important cause of life-threatening thrombotic complications

Sticky platelet syndrome (SPS) is a prothrombotic thrombocytopathy with familial occurrence, characterized by hyperaggregability of platelets in response to adenosine diphosphate (ADP), epinephrine (EPI) or both. The syndrome has been identified in approximately 21% of unexplained arterial thrombotic episodes, regarded to be the most common thrombophilia in arterial thrombosis and 13.2% of unexplained venous thromboembolism (VTE). The relatively young age at the first manifestation, relation to fertility and pregnancy, seriousness of the symptoms, easy and effective management of the disorder indicate to the necessity to take it into account in the differential diagnosis of the underlying cause of the thrombotic event. As the various localizations of the thrombosis in SPS have been reported, its management often requires a multidisciplinary approach. This review deals with the clinical aspects of thrombophilia, its etiopathogenesis, diagnosis as well as novel advances in the treatment and outlines the challenges for the further research.