ABSTRACT
Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hemolytic anemia characterized by complement-mediated intravascular hemolysis that is effectively treated with eculizumab. However, treatment responses are reported heterogeneous with some patients presenting residual hemolysis and requiring RBC transfusions. Recent reports have shown that both extravascular hemolysis and incomplete C5 blockade can explain these suboptimal hematological responses. Here we have tested our eculizumab-treated PNH patients (n=12) for signs of hemolysis and assessed complement biomarkers. Patients were also genotyped for complement receptor 1 (CR1, CD35) and C5 polymorphisms and evaluated for free eculizumab in plasma. We report that 10 patients (83%) present parameters suggesting persistent hemolysis, although they did not require additional transfusions. Seven of them (58%) become direct Coombs-test positive as a consequence of treatment, including all patients carrying the low-expression CR1-L allele. CH50 and sC5b-9 assays demonstrate that the persistent low-level hemolysis identified in our treated patients is not a consequence of incomplete C5 blockade, supporting that this hemolysis, as has been suggested previously, results from the extravascular removal of C3 opsonized PNH erythrocytes. We also show that continuous alternative pathway activation in eculizumab-treated individuals carrying the CR1-L allele results in abnormally decreased levels of C3 in plasma that could, potentially, increase their susceptibility to bacterial infections. Finally, we encourage a routine evaluation of free eculizumab levels and terminal pathway activity to personalize eculizumab administration.
Subject(s)
Complement System Proteins/immunology , Hemoglobinuria, Paroxysmal/blood , Hemoglobinuria, Paroxysmal/immunology , Hemolysis/immunology , Antibodies, Monoclonal, Humanized/therapeutic use , Child , Child, Preschool , Complement Activation/drug effects , Complement Activation/immunology , Complement C3/immunology , Complement C5/immunology , Complement Inactivating Agents/therapeutic use , Cytotoxicity, Immunologic , Female , Genetic Predisposition to Disease , Genetic Variation , Genotype , Hemoglobinuria, Paroxysmal/diagnosis , Hemoglobinuria, Paroxysmal/drug therapy , Humans , Infant , Male , Receptors, Complement 3b/genetics , Receptors, Complement 3b/metabolism , Treatment OutcomeABSTRACT
Fundamento y objetivo: El control de la diabetes mellitus se realiza mediante la determinación de hemoglobina glucosilada (HbA1c) por cromatografía líquida de alta resolución. Algunas variantes estructurales de la hemoglobina (Hb) son conocidas por causar interferencia analítica en la medición de la HbA1c. Pacientes y métodos: En este estudio se ha caracterizado una nueva variante de Hb en 4 pacientes, que se detectó al realizarse un control de HbA1c. Resultados: La secuenciación selectiva del gen α1 mostró una mutación responsable del cambio de ácido aspártico (Asp) por asparagina (Asn) en el codón 64. El cambio de Asp por Asn no produce ninguna alteración funcional de la Hb y se comporta como una hemoglobinopatía silente. Conclusión: Las variantes estructurales de la Hb se pueden detectar durante la medición de la HbA1c y pueden alterar sus valores. Estos casos, aunque poco frecuentes, requieren examinar a fondo los cromatogramas para detectar posibles interferencias (AU)
Background and objective: The glycated hemoglobin (HbA1c) test by high performance liquid chromatography is a useful tool for the follow-up of diabetes mellitus patients. Some structural hemoglobin (Hb) variants are known to cause interference in the analytical measurement of HbA1c. Patients and methods: In this study, it has been characterized a new Hb variant in 4 patients during their regular control of HbA1c. Results: Selective α1 gene sequencing showed a mutation GAC > AAC at codon 64 within exon 2. This produces a change of aspartic acid (Asp) by asparagine (Asn) that does not produce any functional alteration so the resultant molecule behaves as a silent hemoglobinopathy. Conclusion: The structural Hb variants can be detected during the analysis of HbA1c and may alter its values. Though rare, this occurrence signals the need to being aware when measuring HbA1 (AU)
Subject(s)
Humans , Diabetes Mellitus/physiopathology , Glycated Hemoglobin/analysis , Hemoglobinopathies/physiopathology , Base Sequence/genetics , Chromatography, High Pressure LiquidABSTRACT
Fundamento y objetivo. A pesar de que el frotis de sangre periférica es una herramienta muy útil en el diagnóstico de diversas enfermedades, para que aporte beneficio es crucial que el encargado de examinarlo conozca datos clínicos del paciente y sepa qué tiene que buscar o descartar. El objetivo de nuestro trabajo fue evaluar el beneficio real que aporta el frotis y los factores que predicen su impacto en la práctica clínica. Pacientes y métodos. Se analizaron de forma prospectiva todos los frotis consecutivos (n = 618) solicitados en un mes por 6 hospitales de la comunidad de Madrid y revisados en nuestro laboratorio. En cada frotis se evaluó la información previa aportada por el médico peticionario y la serie hematológica alterada. Clasificamos cada frotis, según lo que aportó al clínico, en: a) sin información relevante; b) confirma diagnóstico ya conocido, y c) aporta información relevante para el diagnóstico o pronóstico. Resultados. No se obtuvo ninguna información relevante en 402 frotis (65,04%). En los frotis útiles se observó mayor proporción de sospechas diagnósticas previas (20%) en comparación con los no diagnósticos (5,1%) (p < 0,001) y menos peticiones con hemograma normal (3,8 vs 42,7%, p < 0,001). Conclusiones. En nuestra experiencia, 2 de cada 3 frotis solicitados no aportan ninguna información relevante. Conocer la sospecha diagnóstica y tener al menos una de las 3 series alteradas tiene impacto significativo en la rentabilidad del frotis(AU)
Background and objetive. Although examination of peripheral blood smear is a very helpful tool in the diagnosis of several pathologies, it is essential that the person who performs it knows the patient clinical data and what to look for in order to obtain the highest benefit. The aim of this study is to determine the proportion of useful blood smears in clinical practice and to identify possible predictive factors. Patients and methods. We prospectively analysed 618 consecutive peripheral blood smears performed in our laboratory, requested by 6 hospitals in Madrid. Clinical features provided by the physician and abnormalities in complete blood count (none / white cells / red cells / platelets / all of them) were evaluated in each case. According to the information obtained from them, blood smears were classified into: a) non-diagnostic; b) a previously-known diagnosis is confirmed, and c) new relevant information provided. Results. No useful information was obtained by 402 (65.04%) blood smears. A higher proportion of previous clinical suspicions was observed in helpful blood smears compared to non-diagnostic ones (20% vs 5.1%, P<.001), and also less for completely normal blood counts (3.8% vs 42.7%, P <.001). Conclusions. In our experience, two thirds of requested peripheral blood smears provide no useful information at all. Clinical suspicion and the presence of at least one abnormality in complete blood count showed a significant impact in blood smear yield(AU)
Subject(s)
Humans , Male , Female , Diagnostic Techniques and Procedures/instrumentation , Diagnostic Techniques and Procedures , Blood Chemical Analysis/instrumentation , Blood Chemical Analysis/methods , Prospective Studies , Confidence Intervals , Blood Chemical Analysis/standards , Blood Chemical Analysis/trends , Blood Chemical AnalysisABSTRACT
Dominant inherited beta-thalassemias describe those beta-thalassemia variants that result in a thalassemia intermediate phenotype in individuals who have inherited only a single copy of the abnormal beta gene. This form of thalassemia is characterized by moderately severe anemia with jaundice and splenomegaly; it is also characterized by the presence of inclusion bodies in the red blood cell precursors and has, therefore, previously been referred to as inclusion body beta-thalassemia. We describe a case of inclusion body beta-thalassemia in a 51-year-old Spanish male caused by a deletion of 11 bp (CD 131-134) in exon 3 of the beta-globin gene. The deletion of 11 bp in exon 3 of the beta-globin chain is predicted to produce an anomalous chain of 134 amino acids instead of the normal 146 with an extremely altered amino acid sequence from residues 131-134. Although this shortened variant would lead to a missing H helix, which is involved in alpha1beta1 contact and alpha1beta2 subunit interactions, the variant chain can still be bound to the heme group and acquire a secondary structure that is not suitable for the formation of stable dimers or tetramers and also less susceptible to proteolytic degradation. This is the first report of such a beta-thalassemia mutation.
