[Hemoglobin Woodville associated with double point mutation in the gene of glucose-6-phosphate dehydrogenase]. / Hemoglobina Woodville asociada a una doble mutación puntual en el gen de la glucosa-6-fosfato deshidrogenasa.

The co-inheritance of erythrocyte defects, hemoglobinopathies, enzymopathies, and membranopathies is not an unusual event. For the diagnosis, a laboratory strategy, including screening and confirmatory tests, additional to molecular characterization, was designed. As the result of this approach, a 24-year-old man carrying a hemoglobinopathy (Hemoglobin Woodville) and an enzymopathy (glucose-6-phosphate dehydrogenase deficiency) was identified. In the heterozygous state hemoglobin Woodville, is asymptomatic, and homozygous or double heterozygous individuals have not been reported thus far. On the other hand, previously described double point mutation in the gene for glucose-6-phosphate dehydrogenase c. [202G>A; 376A>G], p. [Val 68Met; Asn126Asp], causes hemolysis of varying severity after food or drug intake or infections. This case highlights the importance of the methodology carried out for the diagnosis, treatment, and proper genetic counseling.

A new ß(0) frameshift mutation, HBB: c.44delT (p.Leu14ArgfsX5), identified in an Argentinean family associated with secondary genetic modifiers of ß-thalassemia.

ß-Thalassemia intermedia (ß-TI) patients present with a wide spectrum of phenotypes depending on the presence of primary, secondary, and tertiary genetic modifiers which modulate, by different mechanisms, the degree of imbalance between α and ß chains. Here we describe a new ß(0) frameshift mutation, HBB: c.44delT (p.Leu14ArgfsX5), identified in four members of a family, associated with secondary genetic modifiers in three of them. The different genotype present in this family was suspected after hematological analysis and thorough observation of blood smears highlighting their importance in the identification of ß-TI patients among members of the same family.

Von Willebrand disease in children: diagnosis and management of a pediatric cohort in one single center in Argentina.

Clinical and laboratory data of children with von Willebrand disease (VWD) types have been derived from retrospective studies and small case series. This article reports on the clinical and laboratory data of a large pediatric cohort in one single Argentinian center. The biological and clinical responses to desmopressin and replacement therapies are also described. Over a 15-year period, 194 of 1150 children (16.9%) were diagnosed as having type 1 VWD (80%), type 2 VWD (19%), and type 3 VWD (1%). The distribution of the different type 2 VWD subtypes was type 2A VWD, 43%; type 2B VWD, 32%; type 2M VWD, 19%; and type 2N VWD, 6%. Eighty patients with type 1 VWD and 12 patients with type 2 VWD were prospectively evaluated to desmopressin (DDAVP) response. A complete response was observed in all children with type 1 VWD, whereas 40% of the children with severe type 1 VWD and with type 2 VWD achieved a complete response. All the children who received DDAVP as prophylaxis or treatment for bleeding had good clinical evolution. Considering the restricted availability of specialized hemostasis centers, we believe our clinical and laboratory approach appropriate for the detection of patients with different types of VWD. Further studies are necessary to determine epidemiological aspects of VWD in Argentina to estimate the necessary facilities and trained personnel for the diagnosis and management of patients with VWD.

Six novel variants in the PKLR gene associated with pyruvate kinase deficiency in Argentinian patients.

BACKGROUND: Pyruvate kinase deficiency (PKD) is a rare recessive congenital hemolytic anemia caused by mutations in the PKLR gene. The disease shows a marked variability in clinical expression. We studied the molecular features of nine unrelated Argentinian patients with congenital hemolytic anemia associated with erythrocyte pyruvate kinase deficiency. DESIGN AND METHODS: Routine hematologic investigations were performed to rule out other causes of chronic hemolytic anemia. Sanger sequencing and in-sílico analysis were carried out to identify and characterize the genetics variants. RESULTS: Six different novel missense variants were detected among the 18 studied alleles: c.661 G > C (Asp221His), c.956 G > T (Gly319Val), c.1595 G > C (Arg532Pro), c.347 G > A (Arg116Gln), c.1232 G > T (Gly411Val), c.1021G > A (Gly341Ser). Structural implications of amino-acid substitutions were correlated with the clinical phenotypes seen in the probands. CONCLUSIONS: This is the first comprehensive report on molecular characterization of pyruvate kinase deficiency in Argentina and the second from South America that would contribute to our knowledge on the distribution and frequency of PKLR variants in our population but also offer new insights into the interpretation of the effect of PKLR variants and phenotype.

Hb S-San Martin: a new sickling hemoglobin with two amino acid substitutions [ß6(A3)Glu→Val;ß105(G7)Leu→Pro] in an Argentinean family.

A new sickling hemoglobin (Hb) detected in an Argentinean family from San Martín, Buenos Aires, Argentina, is hereby described. Two mutations were identified on the same ß-globin gene resulting in a new variant named Hb San Martin. One mutation was found on exon 1, corresponding to Hb S [ß6Glu→Val, GAG>GTG] and the second one on exon 3 at ß105(G7)Leu→Pro, CTC>CCC. The replacement of leucine by proline will likely impair the structure breaking helix G and causing instability of the molecule and the clinical manifestations typical of unstable Hbs. The mutation at ß105 seemed to be a de novo one in our patients, arising on a previously mutated gene, due to the fact that Hb S is the most frequent structural variant.

[Hereditary xerocytosis. Presentation of two pediatric cases]. / Xerocitosis hereditaria. Presentación de dos casos clínicos pediátricos.

Hereditary xerocytosis is a rare disorder caused by defects of red blood cell permeability that are characterized by hemolytic anemia of variable degree and iron overload. Diagnosis is usually late and confused with other hemolytic anemias, which can lead to procedural indications, such as splenectomy, contraindicated in these patients. We report the clinical, haematological, and molecular characteristics of two patients from two unrelated families affected by hereditary xerocytosis. Both patients had dehydrated erythrocytes with a high concentration of mean corpuscular hemoglobin, non-pathognomonic smears, markers of hemolysis and a resistant osmotic fragility curve. The diagnosis was confirmed by the sequencing of the PIEZO gene. We emphasize the importance of recognizing the cause of hemolytic anemia to give an accurate therapeutic approach and give adequate genetic counseling.

La xerocitosis hereditaria es un desorden poco frecuente causado por defectos en la permeabilidad eritrocitaria, que se caracteriza por anemia hemolítica de gravedad variable y sobrecarga de hierro. El diagnóstico suele ser tardío y confundirse con otras anemias hemolíticas, lo que puede llevar a indicaciones de procedimientos, como la esplenectomía, contraindicados en estos pacientes. Se reportan las características clínicas, hematológicas y moleculares de dos pacientes pediátricos no relacionados con diagnóstico de xerocitosis hereditaria. Ambos presentaban eritrocitos deshidratados con alta concentración de hemoglobina corpuscular media, frotis no patognomónico, marcadores de hemólisis y una curva de fragilidad osmótica resistente. El diagnóstico se confirmó por la secuenciación del gen PIEZO. Se resalta la importancia de reconocer la causa de la anemia hemolítica para dar un enfoque terapéutico preciso y dar adecuado consejo genético.

Phenotypic and genotypic characterization of glucose-6-phosphate dehydrogenase deficiency in Argentina. Retrospective and descriptive study. / Caracterización fenotípica y genotipica de la deficiencia de glucosa-6-fosfato deshidrogenasa en Argentina. Estudio retrospectivo y descriptivo.

Glucose-6-phosphate dehydrogenase deficiency is an erythrocyte enzyme disorder caused by mutations in the G6PD gene, which has an X-linked inheritance. Here we analyze the clinical and laboratory characteristics of 24 subjects with G6PD deficiency over 25 years. Their median age at diagnosis was 10.2 years (range: 0.6-56.4). No symptoms were observed in 54.2 % of patients, whereas 25 % had chronic non-spherocytic hemolytic anemia; 12.5 %, neonatal jaundice and postinfectious hemolytic anemia; and 8.3 %, acute hemolytic anemia after ingestion of fava beans. The 24 studied patients had variants that had been previously described in the bibliography. The clinical characteristics observed here were consistent with the variants found. A total of 21 women from the maternal line of affected subjects were identified as deficiency carriers using molecular biology techniques, so they received the corresponding genetic counseling.

La deficiencia de glucosa-6-fosfato deshidrogenasa es la enzimopatía eritrocitaria causada por mutaciones en el gen G6PD, cuya herencia está ligada al cromosoma X. Se analizan las características clínicas y de laboratorio de 24 individuos con deficiencia de G6PD durante 25 años. La edad mediana al momento del diagnóstico fue 10,2 años (rango: 0,6-56,4). El 54,2 % de los pacientes fueron asintomáticos, mientras que el 25 % presentó anemia hemolítica crónica no esferocítica; el 12,5 %, ictericia neonatal y anemia hemolítica posinfecciones, y el 8,3 %, anemia hemolítica aguda pos ingesta de habas. Los 24 pacientes estudiados presentaron variantes descritas previamente en la literatura. Las características clínicas observadas estuvieron acordes con las variantes encontradas. Veintiuna mujeres, pertenecientes a la rama materna de los individuos afectados, pudieron ser identificadas por biología molecular como portadoras de la deficiencia, por lo que recibieron el consejo genético correspondiente.

Two novel DNA variants associated with glucose-6-phosphate dehydrogenase deficiency found in Argentine pediatric patients.

OBJECTIVE: The enzyme glucose-6-phosphate dehydrogenase (G6PD) catalyses the first step in the pentose phosphate pathway, producing nicotinamide adenine dinucleotide phosphate (NADPH). NADPH plays a crucial role in preventing oxidative damage to proteins and other molecules in cells, mostly red blood cells. G6PD deficiency has an x-linked pattern of inheritance in which hemizygous males are deficient, while females may or may not be deficient depending on the number of affected alleles. We report two novel DNA variants in the G6PD gene detected in two male probands with chronic nonspherocytic hemolytic anemia (CNSHA), who were referred for hematological evaluation. METHOD: Probands and their relatives underwent clinical, biochemical, and molecular assessment. RESULTS: Two novel DNA variants, c.995C>T and c.1226C>A, were found in this study. At the protein level, they produce the substitution of Ser332Phe and Pro409Gln, respectively. These DNA variants were analyzed in the female relatives of probands for genetic counseling. CONCLUSIONS: The novel DNA variants were classified as class I based on the clinical, biochemical, and molecular evaluations performed.

[Beta thalassemia intermedia: clinical characteristics and molecular analysis. Case series]. / Beta talasemia intermedia: características clínicas y estudio molecular. Serie de casos clínicos.

Beta thalassemia intermedia is a quantitative haemoglobinopathy covering a broad clinical spectrum, that results from the presence of one or two HBB gene mutations associated with secondary and/or tertiary genetic modifiers. We analyze the clinical and laboratory features of 29 patients with beta thalassemia intermedia, assessed over a period of 23 years. Median age was 10.8 years (range: 0.34-60.4). Hypochromic microcytic anemia was seen in 100% of the patients, while only 17.2% had splenomegaly and occasional transfusion requirement. The molecular analysis of patients detected: 3 with two HBB affected genes; 2 with one HBB affected gene and alpha quadruplicate/triplicate genes; 23 with one HBB affected gene and alpha triplicate genes and 1 with two HBB affected genes and polymorphisms of gamma genes. The adequate identification of these patients enables us to give appropriate genetic counseling and implementation of regular clinical follow up.

Factor V Leiden and prothrombin gene G20210A mutation in children with venous thromboembolism.

To determine whether factor V Leiden (FVL) and/or prothrombin gene G20210A mutation (PT20210A) are risk factors for venous thromboembolism (VTE) in Argentinean children. One hundred and thirty consecutive children with VTE were prospectively assisted at a single centre. Blood samples were available from 110 of them for detailed haematological analysis. The prevalence of both mutations was compared with a control group. The odds ratio for VTE was significantly increased in patients with FVL (OR 3.64; 95% CI: 1.14-11.6, p < 0.029) whereas odds ratio for VTE was not significantly increased in patients with PT20210A (OR 1.06; 95% CI: 0.24-4.73, p = 0.938). Combined disorders were found in 5 of the 10 children with the aforementioned mutations. In 21 children (19%) without these mutations other inherited and acquired disorders were detected. Our data show that FVL is a risk factor for VTE whereas PT20210A does not seem to be a risk factor in our paediatric population.

Xerocitosis hereditaria. Presentación de dos casos clínicos pediátricos / Hereditary xerocytosis. Presentation of two pediatric cases

La xerocitosis hereditaria es un desorden poco frecuente causado por defectos en la permeabilidad eritrocitaria, que se caracteriza por anemia hemolítica de gravedad variable y sobrecarga de hierro. El diagnóstico suele ser tardío y confundirse con otras anemias hemolíticas, lo que puede llevar a indicaciones de procedimientos, como la esplenectomía, contraindicados en estos pacientes. Se reportan las características clínicas, hematológicas y moleculares de dos pacientes pediátricos no relacionados con diagnóstico de xerocitosis hereditaria. Ambos presentaban eritrocitos deshidratados con alta concentración de hemoglobina corpuscular media, frotis no patognomónico, marcadores de hemólisis y una curva de fragilidad osmótica resistente. El diagnóstico se confirmó por la secuenciación del gen PIEZO.Se resalta la importancia de reconocer la causa de la anemia hemolítica para dar un enfoque terapéutico preciso y dar adecuado consejo genético

Hereditary xerocytosis is a rare disorder caused by defects of red blood cell permeability that are characterized by hemolytic anemia of variable degree and iron overload. Diagnosis is usually late and confused with other hemolytic anemias, which can lead to procedural indications, such as splenectomy, contraindicated in these patients. We report the clinical, haematological, and molecular characteristics of two patients from two unrelated families affected by hereditary xerocytosis. Both patients had dehydrated erythrocytes with a high concentration of mean corpuscular hemoglobin, non-pathognomonic smears, markers of hemolysis and a resistant osmotic fragility curve. The diagnosis was confirmed by the sequencing of the PIEZO gene. We emphasize the importance of recognizing the cause of hemolytic anemia to give an accurate therapeutic approach and give adequate genetic counseling.

Caracterización fenotípica y genotipica de la deficiencia de glucosa-6-fosfato deshidrogenasa en Argentina: Estudio retrospectivo y descriptivo / Phenotypic and genotypic characterization of glucose-6-phosphate dehydrogenase deficiency in Argentina: Retrospective and descriptive study

La deficiencia de glucosa-6-fosfato deshidrogenasa es la enzimopatía eritrocitaria causada por mutaciones en el gen G6PD, cuya herencia está ligada al cromosoma X. Se analizan las características clínicas y de laboratorio de 24 individuos con deficiencia de G6PD durante 25 años. La edad mediana al momento del diagnóstico fue 10,2 años (rango: 0,6-56,4). El 54,2 % de los pacientes fueron asintomáticos, mientras que el 25 % presentó anemia hemolítica crónica no esferocítica; el 12,5 %, ictericia neonatal y anemia hemolítica posinfecciones, y el 8,3 %, anemia hemolítica aguda pos ingesta de habas. Los 24 pacientes estudiados presentaron variantes descritas previamente en la literatura. Las características clínicas observadas estuvieron acordes con las variantes encontradas. Veintiuna mujeres, pertenecientes a la rama materna de los individuos afectados, pudieron ser identificadas por biología molecular como portadoras de la deficiencia, por lo que recibieron el consejo genético correspondiente.

Glucose-6-phosphate dehydrogenase deficiency is an erythrocyte enzyme disorder caused by mutations in the G6PD gene, which has an X-linked inheritance. Here we analyze the clinical and laboratory characteristics of 24 subjects with G6PD deficiency over 25 years. Their median age at diagnosis was 10.2 years (range: 0.6-56.4). No symptoms were observed in 54.2 % of patients, whereas 25 % had chronic non-spherocytic hemolytic anemia; 12.5 %, neonatal jaundice and postinfectious hemolytic anemia; and 8.3 %, acute hemolytic anemia after ingestion of fava beans. The 24 studied patients had variants that had been previously described in the bibliography. The clinical characteristics observed here were consistent with the variants found. A total of 21 women from the maternal line of affected subjects were identified as deficiency carriers using molecular biology techniques, so they received the corresponding genetic counseling.

Hemoglobinas inestables / Unstable hemoglobins / Hemoglobinas instáveis

Las variantes estructurales de hemoglobina son, en su mayoría, el resultado de sustituciones puntuales de aminoácidos en una de las cadenas de globina. En muchos casos, estas hemoglobinopatías son inocuas, mientras que en otros determinan alteraciones en la estabilidad y función de la hemoglobina, ocasionando manifestaciones clínicas de severidad variable. En las hemoglobinas inestables, las alteraciones disminuyen la solubilidad, y así facilitan la formación de complejos de hemoglobina precipitada y desnaturalizada (Cuerpos de Heinz) que ocasionan el daño de la membrana y finalmente la destrucción prematura de los eritrocitos. Representan una rara etiología de anemia hemolítica congénita. Hasta la actualidad se han descrito alrededor de 150 hemoglobinas inestables diferentes, la mayoría de las cuales ocasionan hemólisis crónica, exacerbada por infecciones o la ingesta de medicamentos. Su diagnóstico puede ser difícil, sobre todo en pacientes no esplenectomizados. Su identificación requiere inicialmente de la sospecha clínica, pero dado que las pruebas básicas de laboratorio pueden no ser concluyentes e inducir un diagnóstico erróneo, el estudio molecular será necesario para la confirmación.

The structural hemoglobin variants mostly result from single amino-acid substitutions in globin chains. In many cases these are innocuous, but in others they may alter the stability or functional properties of hemoglobin, leading to clinical manifestations of variable severity. They represent a rare cause of congenital hemolytic anemia. Unstable hemoglobins cause alterations that reduce solubility, with increased tendency to Heinz Body formation, damaging red blood cell membrane and finally the premature destruction of red blood cells. Up to 150 unstable hemoglobins have been described; most of them cause chronic hemolytic anemia, aggravated by infections and or drugs. Diagnosis can be difficult, especially in non-splenectomized patients. Initially, identification requires a high degree of clinical suspicion, but due to the fact that basic laboratory tests might be inconclusive, molecular analysis is necessary for final confirmation.

As variantes estruturais de hemoglobina são, em sua maioria, o resultado de substituições pontuais de aminoácidos numa das cadeias de globina. Em muitos casos, estas hemoglobinopatias são inócuas, ao passo que em outros determinam alterações na estabilidade e função da hemoglobina, produzindo manifestações clínicas de severidade variável. Nas hemoglobinas instáveis, as alterações diminuem a solubilidade, facilitando a formação de complexos de hemoglobina precipitada e desnaturalizada (Corpos de Heinz) que ocasionam o dano da membrana e finalmente a destruição prematura dos eritrócitos. Representam uma rara etiologia de anemia hemolítica congênita. Até a atualidade foram descritas aproximadamente 150 hemoglobinas instáveis diferentes, a maioria das quais produzem hemólise crônica, exacerbada por infecções ou pela ingestão de medicamentos. Seu diagnóstico pode ser difícil, principalmente em pacientes não esplenectomizados. Sua identificação requer inicialmente da suspeita clínica, mas devido a que as provas básicas de laboratório podem não ser concluintes e induzir um diagnóstico errado, o estudo molecular será necessário para a confirmação.

[Severe hemolytic anemia due to hemoglobin Southampton: case report]. / Anemia hemolítica grave causada por hemoglobina Southampton: presentación de caso clínico.

Variant hemoglobins are the result of different types of mutations that occur in the globin genes. In many cases, these hemoglobinopathies are harmless, while in others they determine alterations in the physical and chemical properties raising clinical manifestations of variable severity. In the unstable hemoglobinopathies, the changes reduce solubility, inducing the formation of precipitates of denaturated hemoglobin (Heinz bodies), which damage the membrane and finally destroy the red blood cells prematurely. Up to now, more than 142 different unstable hemoglobins have been described, most of them cause chronic hemolysis, increased by infections or drugs. We report the clinical presentation of an unstable hemoglobin (hemoglobin Southampton) in a girl with severe hemolytic anemia, splenomegaly and red blood cell requirement.

[Glucose 6 phosphate dehydrogenase deficiency: a case series]. / Deficiencia de glucosa-6-fosfato deshidrogenasa: Serie de casos clínicos.

We describe the laboratory and clinical characteristics of 50 patients with glucose 6 phosphate dehydrogenase deficiency (G6PD). G6PD deficiency represented 1.1% of all the diagnosis made. Coexistence of G6PD with other erythropathy was detected as follow: G6PG/HbS 2 patients and G6PG/hereditary spherocytosis 1 patient. A positive Brewer's test was found in 100% of males but in only 56% of women. Males had a mean enzymatic activity (MEA) of 0.85 ± 0.52 U/g Hb. Women, with positive Brewer's test, showed a MEA of 3.82 ± 1.26 U/g Hb, while the MEA of women with negative Brewer's test was 5.65 ± 2.84 U/g Hb. Genetic counseling and the list of food and drugs potentially harmful was given to all patients. The inclusion of simple screening tests, such as Brewer's test, in the study of anemia, enables us to detect asymptomatic males and carriers in whom this enzymopathy was co-inherited with another erythropathy.

Prospective study of low-dose ristocetin-induced platelet aggregation to identify type 2B von Willebrand disease (VWD) and platelet-type VWD in children.

Type 2B von Willebrand disease (VWD2B) and platelet-type von Willebrand disease (PT-VWD) are rare bleeding disorders characterised by an increased ristocetin-induced platelet aggregation (RIPA) at low dose of ristocetin. It was the objective of this study to detect children with VWD2B and PT-VWD using RIPA at low dose of ristocetin (0.5 mg/ml) in the screening evaluation of bleeding disorders, and to analyse the phenotypic data along with the molecular findings. Over a 14-year period, 641 children with personal and family bleeding symptoms or bleeding from birth with previously uncharacterised haemostatic disorders were prospectively studied. Six unrelated patients (0.93%) showed RIPA at low dose of ristocetin. RIPA-based mixing studies identified that the plasma of the six probands and at least one parent from five unrelated families induced aggregation of normal platelets with the addition of low-dose ristocetin. None of the probands' platelets showed aggregation with cryoprecipitate. Low ristocetin cofactor activity/VWF antigen ratio with absent collagen binding activity or thrombocytopenia were detected respectively in only two patients. Molecular analysis of exon 28 of the VWF gene identified mutations in only three patients. No mutation in the GP1BA gene was found. In this large prospective paediatric study, the screening approach including RIPA at low dose of ristocetin permitted the detection of patients with VWD2B that would otherwise have been missed. No patient with phenotype or genotype of PT-VWD was identified. Heterogeneity of bleeding symptoms and phenotypic parameters were found among members of the same family.

Beta talasemia intermedia: características clínicas y estudio molecular. Serie de casos clínicos / Beta thalassemia intermedia: clinical characteristics and molecular analysis. Case series

La beta talasemia intermedia es una hemoglobinopatía de amplio espectro clínico, que surge de la presencia de una o dos mutaciones en el gen HBB, asociada a modificadores genéticos secundarios y/o terciarios. Analizamos las características clínicas y de laboratorio de 29 pacientes con beta talasemia intermedia, evaluados en un período de 23 años. La edad mediana fue de 10,8 años (rango: 0,34-60,4). El 100% de los pacientes mostró anemia microcítica hipocrómica, y solo el 17,2% presentó esplenomegalia y requerimiento transfusional esporádico. El análisis molecular de los pacientes detectó 3 con los dos genes HBB afectados; 2 con un gen HBB afectado y genes alfa cuadriplicados/triplicados; 23 con un gen HBB afectado y genes alfα triplicados; y 1 con dos genes HBB afectados y polimorfismos de genes gama. La correcta identificación de estos pacientes aseguró un adecuado consejo genético y la implementación de controles clínicos regulares.(AU)

Beta thalassemiaintermediaisaquantitative haemoglobinopathy covering a broad clinical spectrum, that results from the presence of one or two HBB gene mutations associated with secondary and/or tertiary genetic modifiers. We analyze the clinical and laboratory features of 29 patients with beta thalassemia intermedia, assessed over a period of 23 years.(AU)