RESUMEN

The incidence of thrombosis is higher among newborn infants than in any other stage of pediatric development. This fact is the consequence of labile characteristics of the neonatal hemostatic system, in addition to exposure to multiple risk factors and the wide use of vascular catheters. Venous thromboses, which mainly affect the limbs, the right atrium and renal veins, are more frequently seen than arterial thromboses. A stroke may be caused by the occlusion of the arterial flow entering the brain or by occlusion of its venous drainage system. Purpura fulminans is a very severe condition that should be treated as a medical emergency, and is secondary to severe protein C deficiency or, less frequently, protein S or antithrombin deficiency. Most thrombotic events should be managed with antithrombotic therapy, which is done with unfractionated and/or low molecular weight heparins. Purpura fulminans requires protein C replacement and/or fresh frozen plasma infusion. Thrombolytic therapy is done using tissue plasminogen activator and should only be used for life-, or limb-, or organ-threatening thrombosis.

La probabilidad de padecer trombosis es mucho mayor en el período neonatal que en cualquier otra etapa pediátrica. La labilidad del particular sistema hemostático del neonato, sumada a los múltiples factores de riesgo a que está expuesto y la presencia casi constante de catéteres, son responsables de este hecho. Las trombosis venosas son más frecuentes que las arteriales y ocurren principalmente en los miembros, la aurícula derecha y las venas renales. El accidente cerebrovascular puede ser causado por la oclusión del flujo arterial que llega al cerebro o del sistema de drenaje venoso de este. La púrpura fulminans es una patología de altísima gravedad, que debe ser considerada una emergencia médica y se debe a la deficiencia grave de proteína C o, menos frecuentemente, de proteína S o antitrombina. La mayoría de los episodios trombóticos tienen indicación de tratamiento anticoagulante, que se puede realizar con heparina no fraccionada y/o con heparina de bajo peso molecular. La púrpura fulminans requiere terapia de sustitución con proteína C y/o plasma fresco. El tratamiento trombolítico se realiza con activador tisular del plasminógeno y debe quedar reservado solo para aquellas trombosis cuya localización implique compromiso de vida o pérdida de un órgano o de un miembro.

Asunto(s)

RESUMEN

La probabilidad de padecer trombosis es mucho mayor en el período neonatal que en cualquier otra etapa pediátrica. La labilidad del particular sistema hemostático del neonato, sumada a los múltiples factores de riesgo a que está expuesto y la presencia casi constante de catéteres, son responsables de este hecho. Las trombosis venosas son más frecuentes que las arteriales y ocurren principalmente en los miembros, la aurícula derecha y las venas renales. El accidente cerebrovascular puede ser causado por la oclusión del flujo arterial que llega al cerebro o del sistema de drenaje venoso de este. La púrpura fulminans es una patología de altísima gravedad, que debe ser considerada una emergencia médica y se debe a la deficiencia grave de proteína C o, menos frecuentemente, de proteína S o antitrombina. La mayoría de los episodios trombóticos tienen indicación de tratamiento anticoagulante, que se puede realizar con heparina no fraccionada y/o con heparina de bajo peso molecular. La púrpura fulminans requiere terapia de sustitución con proteína C y/o plasma fresco. El tratamiento trombolítico se realiza con activador tisular del plasminógeno y debe quedar reservado solo para aquellas trombosis cuya localización implique compromiso de vida o pérdida de un órgano o de un miembro.

The incidence of thrombosis is higher among newborn infants than in any other stage of pediatric development. This fact is the consequence of labile characteristics of the neonatal hemostatic system, in addition to exposure to multiple risk factors and the wide use of vascular catheters. Venous thromboses, which mainly affect the limbs, the right atrium and renal veins, are more frequently seen than arterial thromboses. A stroke may be caused by the occlusion of the arterial flow entering the brain or by occlusion of its venous drainage system. Purpura fulminans is a very severe condition that should be treated as a medical emergency, and is secondary to severe protein C deficiency or, less frequently, protein S or antithrombin deficiency. Most thrombotic events should be managed with antithrombotic therapy, which is done with unfractionated and/or low molecular weight heparins. Purpura fulminans requires protein C replacement and/or fresh frozen plasma infusion. Thrombolytic therapy is done using tissue plasminogen activator and should only be used for life-, or limb-, or organ-threatening thrombosis.

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RESUMEN

Two distinct syndromes that link α-thalassemia and intellectual disability (ID) have been described: ATR-X, due to mutations in the ATRX gene, and ATR-16, a contiguous gene deletion syndrome in the telomeric region of the short arm of chromosome 16. A critical region where the candidate genes for the ID map has been established. In a pediatric patient with Hemoglobin H disease, dysmorphic features and ID, 4 novel and clinically relevant Copy Number Variants were identified. PCR-GAP, MLPA and FISH analyses established the cause of the α-thalassemia. SNP-array analysis revealed the presence of 4 altered loci: 3 deletions (arr[hg19]Chr16(16p13.3; 88,165-1,507,988) x1; arr[hg19]Chr6(6p21.1; 44,798,701-45,334,537) x1 and arr[hg19]Chr17(17q25.3; 80,544,855-81,057,996) x1) and a terminal duplication (arr[hg19]Chr7(7p22.3-p22.2; 4,935-4,139,785) x3). The -α(3.7) mutation and the ∼1.51 Mb in 16p13.3 are involved in the alpha-thalassemic phenotype. However, the critical region for ATR-16 cannot be narrowed down. The deletion affecting 6p21.1 removes the first 2 exons and part of intron 2 of the RUNX2 gene. Although heterozygous loss of function mutations affecting this gene have been associated with cleidocranial dysplasia, the patient does not exhibit pathognomonic signs of this syndrome, possibly due to the fact that the isoform d of the transcription factor remains unaffected. This work highlights the importance of searching for cryptic deletions in patients with ID and reiterates the need of the molecular analysis when it is associated to microcytic hypochromic anemia with normal iron status.

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Hereditary spherocytosis must always be suspected in children with anemia, hyperbilirubinemia, splenomegaly or cholelithiasis, in the asymptomatic individual with an affected relative, and in the neonate with hyperbilirubinemia with no blood group incompatibility; its early detection is key to avoid kernicterus. Follow-up of these patients is based on periodical control and supply of information on the adequate management of hemolytic or aplastic crisis, and early detection of cholelithiasis. The decision to perform splenectomy is usually associated with quality of life rather than life-threatening risk, and it should result from a consensus between patient, parents and physicians. The postsplenectomy follow-up is based on control of compliance with the prophylactic antibiotic therapy and the early diagnosis of infectious disorders.

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RESUMEN

Hereditary spherocytosis is the most frequent hereditary anemia excluding beta thalassemia in Argentina. Historical, demographic, genetic and pathogenic aspects of the disease are reviewed, and confirmatory laboratory tests are described. Special characteristics on the outcome of the disease in our population and prevalent protein deficiencies in our country are described. Emphasis is given on new available laboratory tests, which allow an earlier diagnosis using volume of blood samples significantly smaller than required for conventional tests.

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RESUMEN

La esferocitosis hereditaria es la anemia hereditaria más frecuente en nuestro país luego de la talasemia menor. En este artículo, se revisan aspectos históricos, demográficos, genéticos y etiopatogénicos de la enfermedad, y se describen las pruebas de laboratorio para su diagnóstico. Se remarca el comportamiento de la enfermedad en nuestra población y se detallan las deficiencias proteicas predominantes en nuestro país. Se enfatiza sobre las nuevas técnicas de laboratorio actualmente disponibles, con alta sensibilidad y especificidad, que permiten realizar un diagnóstico más temprano con volúmenes de muestra mucho menores que los necesarios para las pruebas convencionales.

Hereditary spherocytosis is the most frequent hereditary anemia excluding beta thalassemia in Argentina. Historical, demographic, genetic and pathogenic aspects of the disease are reviewed, and confirmatory laboratory tests are described. Special characteristics on the outcome of the disease in our population and prevalent protein deficiencies in our country are described. Emphasis is given on new available laboratory tests, which allow an earlier diagnosis using volume of blood samples significantly smaller than required for conventional tests.

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The impaired hematopoiesis in acquired aplastic anemia (AA) results from immune-mediated mechanisms. We characterized polymorphisms implicated in controlling type-1 cytokine production in 69 patients with AA. Our data suggest that the studied polymorphisms are not associated with susceptibility in the overall AA population. However, the presence of the higher expressing TNF - 308A allele was associated with younger age (p = 0.0297) and more profound neutropenia (p = 0.0312), and over-represented in patients with very severe AA (p = 0.0168). The higher producing IFNG 12 CA-repeat allele showed strong linkage disequilibrium with the + 874T allele, and was associated with a lower hemoglobin level (p = 0.0351). Also, the presence of at least one higher expressing variant was more frequent among patients responding to immunosuppressive treatment (p = 0.0519). Our findings suggest that the presence of higher expressing variants of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) in AA patient genotypes could be related to clinical parameters, disease severity and therapy outcomes.

Asunto(s)

RESUMEN

Hereditary spherocytosis is the most frequent hereditary anemia excluding beta thalassemia in Argentina. Historical, demographic, genetic and pathogenic aspects of the disease are reviewed, and confirmatory laboratory tests are described. Special characteristics on the outcome of the disease in our population and prevalent protein deficiencies in our country are described. Emphasis is given on new available laboratory tests, which allow an earlier diagnosis using volume of blood samples significantly smaller than required for conventional tests.