Detection of alloimmunization in Glanzmann Thrombasthenia and Bernard-Soulier Syndrome: Data from a Brazilian Center

ABSTRACT Introduction: The Glanzmann Thrombasthenia (GT) and Bernard-Soulier Syndrome (BSS) are rare hereditary disorders of platelet function. Their treatment often requires platelet transfusion, which can lead to the development of alloantibodies. Objective: In this study, we aim to develop a strategy for alloantibody detection and to describe the frequency of alloimmunization in a patient population from a single center in southeastern Brazil. Methods: Samples from patients with GT or BSS were tested using the Platelet Immunofluorescence Test (PIFT). If a positive result was obtained, a confirmatory step using the Monoclonal Antibody Immobilization of Platelet Antigens (MAIPA) and Luminex bead-based platelet assay (PAKLx) was executed. Main results: Among 11 patients with GT, we detected the presence of alloantibodies in 5 using PIFT, with confirmation through MAIPA and PAKLx in 2 (1 anti-HLA and 1 anti-HPA), resulting in a frequency of 18.1%. Among 4 patients with BSS, PIFT was positive in 3, with confirmation by MAIPA and PAKLx in 1 (anti-HLA), showing a frequency of 25%. The two patients with anti-HLA antibodies exhibited a panel reactive antibody (PRA-HLA) testing greater than 97%. Conclusion: Our study highlights the importance of identifying platelet alloimmunization in this patient population. The proposed algorithm for platelet alloantibodies detection allows resource optimization.

Síndrome de Bernard-Soulier / Bernard-Soulier síndrome

Resumen: El síndrome de Bernard-Soulier ocupa el séptimo lugar entre los trastornos de la coagulación más comunes y es una enfermedad poco frecuente de carácter genético, que se distingue por disfunción o ausencia del complejo plaquetario glicoproteína Ib-IX-V, que es el principal receptor del factor de von Willebrand, importante en la adhesión plaquetaria al subendotelio. Su incidencia puede llegar a ser de más de un caso por millón porque a menudo es mal diagnosticado si el paciente no manifiesta los datos clínicos típicos o si no hay resultados de laboratorio concluyentes. Los pacientes manifiestan macrotrombocitopenia con recuentos de plaquetas variables, además de prolongación del tiempo de coagulación. A la fecha se han descrito más de 100 mutaciones relacionadas con los componentes del complejo plaquetario, la manifestación de la enfermedad puede llegar a ser muy heterogénea incluso en pacientes que tengan una mutación idéntica.

Abstract: The Bernard-Soulier syndrome ranked seventh among the most common coagulation disorders; it is a rare genetic disease, characterized by dysfunction or absence of the glycoprotein Ib-IX-V platelet complex, which is the main receptor of von Willebrand factor, important in platelet adhesion to the subendothelium. Its incidence can be more than 1 per 1 million because it is often misdiagnosed if the patient does not present with the typical clinic or if there are no conclusive laboratory results. The syndrome presents macrothrombocytopenia with variable platelet counts as well as prolongation of the coagulation time. To date, more than 100 mutations related to the components of the platelet complex have been described, the presentation of the disease can become very heterogeneous even in patients who have an identical mutation.

Bernard Soulier Syndrome; A Rare Bleeding Disorder

Bleeding syndromes in the newborn are rare, but they may be life-threatening and demand immediate attention. Congenital bleeding disorders especially pose a diagnostic challenge to the clinician because of their rarity and the need to be differentiated from the other common causes of bleeding in children. We present a case of an infant presenting with bleeding symptoms early in his life (since 5 months of age) which was initially thought to be immune thrombocytopenic purpura (ITP) with low platelet count. No response to steroids and further evaluation by platelet aggregometry and flowcytometry led to the correct diagnosis – Bernard soulier syndrome(BSS). Though, there is no specific treatment available for this rare bleeding disorder, however it is imperative to have arrived at correct diagnosis in order to save unnecessary therapy and to take due precautions for prevention of bleeding.

Trombocitopenia familiar de plaquetas gigantes: caso clínico / Familiar Thrombocytopenia of Giant Platelets: Clinical Case

La trombocitopenia es causa frecuente de consulta en hematología pediátrica. La mayoría de veces la baja de plaquetas es por desorden de destrucción autoinmune, raramente el padecimiento tiene un comportamiento familiar-hereditario. Se presenta el caso de una paciente de 11 años de edad, conocida desde los 3 años por trombocitopenia en el rango de 50,000/mm , fue evaluada por posibilidad de desórdenes autoinmunescon estudios inmunológicos básicos: complementos, ANA, Anti ADN, factor reumatoide y los resultados fueron normales. Tratada en varias ocasiones con prednisona oral, antiRh y con inmunoglobulina intravenosa (IGIV). Se le ha brindado seguimiento prolongado por trombocitopenia que resultó ser familiar; encontrando doce afectados, que incluyen abuela materna, madre, tíos, primos y hermana. Las características clínicas y la morfología plaquetaria fueron finalmente suficientes para conducir a diagnóstico inusual: el síndrome de Bernard-Soulier (SBS). El diagnóstico fue sugerido por el frotis de sangre periférica (FSP)...

Utilidad clínica de la agregometría plaquetaria / Clinical utility of platelet aggregometry

Resumen: La acción de las plaquetas en la hemostasia primaria comprende la adhesión a losvasos sanguíneos afectados, la activación, la secreción del contenido granular, y posteriormente,la agregación plaquetaria para la formación del tapón hemostático primario. Bajo las condicionesfisiológicas de flujo vascular, estos procesos requieren la acción sinérgica de varias proteínasy receptores plaquetarios, como también de agonistas que inducen la activación plaquetaria.Por ello, las mutaciones de los genes que codifican para moléculas y receptores de superficieimplicados en estos procesos darán origen a desórdenes hemorrágicos como la enfermedad devon Willebrand, la trombastenia de Glanzmann, el síndrome de Bernard Soulier y la deficienciade gránulos plaquetarios, entre otros. El diagnóstico de estas enfermedades se realiza medianteensayos de función plaquetaria que simulan los procesos fisiológicos de activación, adhesión,liberación del contenido granular y agregación. Una de las pruebas de función plaquetaria másutilizada es la agregometría. En este artículo de revisión se describe la utilidad de esta prueba parael diagnóstico de desórdenes hemorrágicos hereditarios y del síndrome de la plaqueta pegajosa,un desorden trombótico hereditario caracterizado por hiperagregabilidad. Adicionalmente, se revisa el fundamento de esta prueba, las condiciones preanalíticas, analíticas y posaanaliticas, analiticas y poanaliticas las indicaciones las contraindicaciones y la interpetación de los resultados.

Abstract: The role of platelets in primary hemostasis involves their adherence to sites of vessel injury, activation, secretion of platelet granule content, and finally, aggregation to form the primaryhemostatic plug. Under physiologic conditions of vascular flow, these processes require thesynergistic action of several proteins and platelet receptors, and also the action of physiologicalagonists that stimulate the activation of the platelets. As a result, hereditary mutations of genescodifying for molecules and surface receptors implied in primary hemostasis will be expressedas hemorrhagic disorders, including von Willebrand disease, Glanzmann thrombasthenia,Bernard Soulier syndrome, storage pool diseases, among others. The diagnosis of these diseases is possible through platelet function assays that resemble the physiological processesof activation, adhesion, release of granule content, and aggregation. Platelet aggregometry isone of the most frequently used tests. This review article intends to describe the utility of plateletaggregometry for the diagnosis of hereditary hemostatic disorders and sticky platelet syndrome, a hereditary thrombotic disorder characterized by increased platelet aggregability. In addition, the fundamentals of the test, the pre-analytical, analytical and post-analytical conditions, the test indications, contraindications and results interpretation are discussed.

Hematological abnormalities and 22q11.2 deletion syndrome

The 22q11.2 deletion syndrome (22q11DS) is a common genetic disease characterized by broad phenotypic variability. Despite the small number of studies describing hematological alterations in individuals with 22q11DS, it appears that these abnormalities are more frequent than previously imagined. Thus, the objective of our study was to report on a patient with 22q11DS presenting thrombocytopenia and large platelets and to review the literature. The patient, a 13-year-old boy, was originally evaluated due to craniofacial dysmorphia and speech delay. He also had a history of behavioral changes, neuropsychomotor delay and recurrent otitis/sinusitis. The identification of a 22q11.2 microdeletion by fluorescent in situ hybridization diagnosed the syndrome. Despite his hematological alterations, he only had a history of epistaxis and bruising of the upper and lower limbs. Assessments of the prothrombin time, thrombin time, partial thromboplastin time, bleeding time, fibrinogen levels and platelet aggregation (including the ristocetin induced platelet aggregation test) were all normal. Hematological alterations observed in 22q11DS are directly related to the genetic disorder itself (especially in respect to deletion of the GPIb gene) and secondary to some clinical findings, such as immunodeficiency. Macrothrombocytopenia is increasingly being considered a feature of the broad spectrum of 22q11DS and may potentially be a clinical marker for the syndrome.

Consideraciones anestésicas en un paciente con enfermedad de von Willebrand y Síndrome

La enfermedad de von Willebrand y el Síndrome de Bernard Soulier son entidades que presenten alteraciones de la coagulación de herencia autosómica dominante y recesiva respectivamente. Se presenta el caso de una paciente con diagnóstico de ambas entidades la cual fue sometida a una amigdalectomía, haciéndose énfasis en su manejo perioperatorio, así como la revisión de la literatura sobe su tratamiento.

summary The von Willebrand disease and the Bernard Soulier syndrome are diseases that present coagulation alterations with dominat and recesive hereditar character respectively. We present a case of a patient with both entites, who was operated of a adenotonsillectomy, making emphasis in the transoperatory management, and including a literature review.

resumo A doença de von Willebrand e a Síndrome de Bernard Soulier são entidades que apresentam alterações da coagulação de herança autossômica dominante e recessiva respectivamente. Se apresenta o caso de uma paciente com diagnóstico de ambas entidades a qual foi submetida a uma amigdalectomia, dando-se ênfase ao seu manejo peri-operatório, assim como a revisão da literatura sobre seu tratamento.