Detección de inhibidor adquirido específico de factor VIII / Diagnosis of acquired inhibitor against factor VIII / Detecção de inibidor adquirido específico de fator VIII

El inhibidor adquirido contra el factor VIII o “hemofilia adquirida” (HA) es una patología autoinmune que suele presentarse como un sangrado súbito en pacientes sin coagulopatía previa. El diagnóstico de esta patología debe ser rápido, sobre todo en aquellos casos en que la presentación es una hemorragia que puede comprometer la vida del paciente. En esta actualización se analizan las pruebas globales y específicas utilizadas en su detección y los ensayos Bethesda y Nijmejen que permiten la cuantificación del inhibidor para monitorear el tratamiento. Es importante la función del laboratorio en el diagnóstico precoz de esta patología y para eso se debe conocer y pensar en su existencia cuando se presenta un paciente con sangrado, un aPTT prolongado que no corrige con plasma normal, un FVIII disminuido y pruebas de inhibidor lúpico negativo.

The acquired inhibitor against factor VIII or “acquired haemophilia” (HA) is an autoimmune disease that usually appears as a sudden bleeding in patients without previos coagulopathy. Diagnosis of this disease must be quick, particularly when the presentation is a bleeding event that compromises the patient’s life. In this update, global and specific tests used in the detection of FVIII inhibitor are described. Besides, Nijmejen and Bethesda assays are analyzed for the quantification of the inhibitor to monitor treatment. The role of the laboratory is important in early diagnosis of this disease so the presence of this rare but life threatening disease must be suspected when a patient shows haemorrhages, prolonged aPTT that does not correct with normal plasma, decreased FVIII and a negative lupus anticoagulant test.

O inibidor contra o fator VIII adquirido ou “hemofilia adquirida” (HA) é uma doença autoimune que geralmente se apresenta como um sangramento súbito em pacientes sem coagulopatia prévia. O diagnóstico da doença deve ser rápido, especialmente nos casos em que a apresentação é uma hemorragia, que pode comprometer a vida do paciente. Nesta atualização são analisadas as provas globais e específicas utilizadas em sua detecção e nos ensaios de Bethesda e Nijmejen que permitem a quantificação do inibidor para monitorizar o tratamento. É importante a função do laboratório no diagnóstico precoce dessa patologia e, para isso, se deve conhecer e pensar na sua existência quando se apresenta um paciente com sangramento, TTPA prolongado que não corrige com plasma normal, um FVIII diminuído e testes de inibidor lúpico negativo.

Síndrome de Nijmegen: una enfermedad genética a considerar en un paciente con microcefalia, retardo mental y lesiones de la piel / Nijmegen breakage syndrome

Se presenta el caso de un paciente masculino que a los 6 años de edad es derivado a Neurología Infantil para su estudio por presentar microcefalia y retardo mental. Tras ser evaluado por Inmunología y Genética se realiza en el Laboratorio de citogenética humana, programa de genética ICBM, Facultad de Medicina Universidad de Chile, PCR para deleción 657 del5 que confirma el diagnóstico de Nijmegen dando como resultado deleción nucleótido 5, mutación 657 del5, característico del Síndrome de Nijmegen. Actualmente el niño tiene 13 años y es tratado en el Servicio de Oncología infantil por el desarrollo de linfoma difuso de células grandes B, patología frecuente en este sindrome.

A case of a male patient at 6 years old was referred to child neurology for study due to microcephaly and mental retardation. After being evaluated for Immunology and Genetics Laboratory is performed in human cytogenetics, genetic program ICBM, Faculty of Medicine University of Chile, PCR for deletion 657 of the 5 that confirms the diagnosis of Nijmegen nucleotide deletion resulting in 5, 657 mutation del 5 Characteristic of the syndrome of Nijmegen. Currently the child is 13 and is treated at the Children’s Oncology Service in the development of lymphoma diffuse large B cell, common pathology in this syndrome.

Differentiation of Nijmegen breakage syndrome from Fanconi anemia

Nijmegen breakage syndrome (NBS) is a rare auto-somal recessive condition with chromosomal instability. Clinical and biological overlap between Fanconi anemia and ataxia telangiectasia has been reported. We report two cases of NBS born to consanguineous parents. Case one had NBS and Falconi anemia clinical features but relatively little chromosome breakage. The second case had mild NBS features, while cytogenetic evaluation with mitomycin C induction showed chromosome damage. Chromosomal analysis of bone marrow cells revealed tetraploidy, which indicates progression towards leukemia. On the basis of clinical and cytogenetic evaluation, these two cases were confirmed as NBS. However, detailed molecular studies are essential for accurate diagnosis and management of this disease.