Hemoglobina Denver, una causa de desaturación en oximetría de pulso. Reporte de caso en un paciente pediátrico / Hemoglobin Denver, a cause of desaturated pulse oximetry. A pediatric case report

Las hemoglobinopatías son trastornos genéticos que afectan a la molécula de hemoglobina (Hb). Las mutaciones en las cadenas a o b que alteran el tetrámero de Hb pueden modificar la capacidad de la molécula para unirse al oxígeno. Las hemoglobinopatías con baja afinidad al oxígeno pueden presentarse con cianosis y una lectura alterada de la oximetría de pulso, lo que lleva a pruebas innecesarias y, a veces, invasivas para descartar afecciones cardiovasculares y respiratorias. En el siguiente reporte de caso, presentamos a una paciente pediátrica, asintomática, que se presentó a la consulta por detección de desaturación en oximetría de pulso. Las pruebas de laboratorio iniciales mostraron una anemia normocítica, normocrómica. Las muestras de gas venoso demostraron una p50 elevada. Después de extensas herramientas de diagnóstico, se diagnosticó una variante de Hb con baja afinidad al oxígeno, Hb Denver.

Hemoglobinopathies are genetic disorders that affect the hemoglobin (Hb) molecule. Mutations in the alpha or beta chains altering the Hb tetramer may modify the molecule's oxygen-binding capacity. Hemoglobinopathies with low oxygen affinity may occur with cyanosis and an altered pulse oximetry reading, leading to unnecessary and sometimes invasive tests to rule out cardiovascular and respiratory conditions. In the case report described here, we present an asymptomatic pediatric patient who consulted for desaturated pulse oximetry. Her initial laboratory tests showed normocytic, normochromic anemia. Venous blood gas samples showed an elevated p50. After using extensive diagnostic tools, a variant of Hb with low oxygen affinity was diagnosed: Hb Denver.

Occurrence of unusual haemoglobinopathies in balochistan: hb sd and hb se - presentation with osteomyelitis / Ocorrência de hemoglobinopatias incomuns no baluchistão: hb sd e hb se - apresentação com osteomielite

ABSTRACT Objective: To describe two cases of unusual variants of sickle cell disease. Case description: We present two cases of sickle cell disease variants (haemoglobinopathies), from unrelated families, in the state of Balochistan (Pakistan). One was diagnosed with sickle cell disease in the haemoglobin electrophoresis, whereas the other was diagnosed with sickle cell SE disease. Both were diagnosed based on the presentation of osteomyelitis. Comments: Haemoglobin SD disease (Hb SD) and haemoglobin SE disease (Hb SE) are rare haemoglobinopathies in the world. The lack of available literature suggests that both are variants of sickle cell disease (SCD), with heterogeneous nature. The prevalence of sickle cell disease with compound heterozygotes was found at a variable frequency in the population of the Asian Southeast. The frequency of osteomyelitis in SCD is 12 to 18%, but its occurrence among variant haemoglobinopathies is little reported. Both reported cases presented with osteomyelitis as a characteristic of the disease presentation.

RESUMO Objetivo: Descrever dois casos de variantes raras da hemoglobinopatia falciforme. Descrição do caso: Apresentamos aqui dois casos de hemoglobinopatias variantes das células falciformes, de famílias não relacionadas, no estado do Baluchistão (Paquistão), sendo um diagnosticado como doença da hemoglobina SD na eletroforese de hemoglobina, enquanto o outro com doença da hemoglobina SE. Ambos foram diagnosticados a partir da apresentação de osteomielite. Comentários: Hemoglobina SD (Hb SD) e hemoglobina SE (Hb SE) são hemoglobinopatias raras no mundo. A escassez de literatura disponível sugere que ambas são variantes da doença falciforme (DF) com natureza heterogênea. A prevalência de hemoglobinopatia falciforme com heterozigosidade composta foi encontrada com frequência variável na população do sudeste asiático. A frequência de osteomielite na DF é de 12 a 18%, mas sua ocorrência entre as hemoglobinopatias falciformes variantes é pouco relatada. Os dois casos reportados apresentaram osteomielite como característica de apresentação da doença.

Importancia de la detección temprana de hemoglobinopatias en la población pediátrica en países en desarrollo / Importance of early detection of hemoglobinopathies in the pediatric population in developing countries

OBJETIVO: Alertar al personal de la salud sobre la importancia de la detección temprana de las he- moglobinopatías, dado que es el trastorno monogénico recesivo más frecuente. Pacientes y MÉTODO: Estudio retrospectivo del resultado de eletroforesis capilar (CE) de 152 pacientes entre 0 y 18 años que durante el año 2017 fueron evaluados por sospecha de hemoglobinopatías en un Hospital Universitario de Colombia. La información se tomó de los registros médicos y del Laboratorio de Hematología y Hemostasia, asegurando la privacidad de los datos y aprobado por el Comité de Ética local. RESULTADOS: De 152 pacientes, 48,6% tenía entre 7 y 18 años. La frecuencia de hemoglobinopatías fue de 42,7%. La variante más frecuente fue el rasgo de células falciformes (Hb S) con 14,5%. El hematólogo fue el profesional que más frecuentemente solicitó EC. DISCUSIÓN: Se detectó que las hemoglobinopatías se diagnostican usualmente en niños mayores de siete años. Esto puede favorecer las complicaciones y progresión de la enfermedad, y aumento en los costos de la salud. Se requiere más información y educación a los médicos generales y pediatras para un diagnóstico más temprano.

OBJECTIVE: The objective of this study is to spread awareness among health personnel about the importance of early detection of hemoglobinopathies since it is the most frequent monogenic recessive disorder worldwide. PATIENTS AND METHOD: Retrospective study of the results of capillary electropho resis (CE) of 152 patients aged between 0 and 18 years who were evaluated in 2017 due to suspected hemoglobinopathies in a University Hospital in Colombia. The information was collected from me dical records and the Hematology and Hemostasis Laboratory, ensuring data privacy and approved by the local Ethics Committee. RESULTS: Of 152 patients, 48.6% were aged between 7 and 18. The frequency of hemoglobinopathies was 42.7%. The most frequent hemoglobin variant was the sickle cell trait (Hb S) with 14.5%. The hematologist was the professional who most frequently requested CE. DISCUSSION: We found that hemoglobinopathies are usually diagnosed late in pediatric patients. This may favor complications and progression of the disease and increase healthcare costs. More information and education are required for general physicians and pediatricians in order to achieve early diagnosis.

Técnicas convencionales aplicadas al diagnóstico de las hemoglobinopatías / Conventional techniques applied to the diagnosis of hemoglobinopathies / Técnicas convencionais aplicadas ao diagnóstico das hemoglobinopatias

Las hemoglobinopatías son trastornos hereditarios debidos a una gran variedad de defectos que afectan a los genes de globina. El diagnóstico de las hemoglobinopatías resulta de una combinación de estudios clínicos, pruebas de laboratorio y estudio familiar. Las herramientas básicas incluyen hemograma, hemoglobina e índices eritrocitarios (VCM, HCM), morfología de los eritrocitos, recuento de reticulocitos y perfil de hierro. Las determinaciones complementarias son electroforesis de hemoglobina que permite separar las diferentes variantes de acuerdo con su carga eléctrica, cuantificación de hemoglobina A2 (HbA2), Fetal (Hb F), pruebas de solubilidad hemoglobínica y falciformación. Otras técnicas se basan en propiedades fisicoquímicas como la estabilidad de la hemoglobina para detección de variantes inestables. En la práctica las pruebas más útiles son las que permiten detectar la presencia de hemoglobinopatías, como ocurre con la hemoglobina S dejando para laboratorios especializados aquellos procedimientos para identificar la mutación. La correcta detección de los portadores de las diferentes hemoglobinopatías tiene como finalidad dar un consejo genético adecuado sobre la forma de herencia, el riesgo de tener hijos afectados con las formas graves de la enfermedad y evitar tratamientos innecesarios. El diagnóstico molecular se reserva para la alfa talasemia, para cuadros con genotipos complejos, estudios prenatales o epidemiológicos.

Hemoglobinopathies are hereditary syndromes determined by a large variety of globin gene defects. Hemoglobinopathy diagnosis results from the combination of clinical orientation, laboratory tests and family studies. Basic tools include complete blood cell count, red blood cell count, hemoglobin quantification and red cell indices (MCV, MCH), blood film examination, reticulocyte count and iron status. Complementary determinations are hemoglobin electrophoresis, which enables the separation of the different hemoglobin variants according to their electrical charge, A2, and Fetal hemoglobin quantification, hemoglobin solubility and sickling test for Hb S diagnosis. Other techniques are based on physicochemical properties such as stability of hemoglobin for detection of unstable variants. In practice, the most useful tests are those that enable the detection of hemoglobinopathies, such as hemoglobin S, and the identification of the genetic defects is referred to specialized laboratories. The correct detection of the carriers of the different hemoglobinopathies is intended to give adequate genetic advice on the form of inheritance and the risk of having affected children with the severe forms of the disease and to avoid unnecessary treatments. Molecular diagnosis is reserved to a thalassemia complex genotypes, prenatal o epidemiological studies.

As hemoglobinopatias são distúrbios hereditários resultantes de uma grande variedade de defeitos que afetam os genes de globina. O diagnóstico das hemoglobinopatias decorre de uma combinação de estudos clínicos, provas de laboratório e estudo familiar. As ferramentas básicas incluem hemograma, hemoglobina e índices eritrocitários (VCM, HCM), morfologia dos eritrócitos, contagem de reticulócitos e perfil de ferro. As determinações complementares são eletroforese de hemoglobina que permite separar as diferentes variantes, de acordo com sua carga elétrica, quantificação de hemoglobina A2 (HbA2), Fetal (Hb F), provas de solubilidade hemoglobínica e falciformação. Outras técnicas baseiam-se em propriedades fisicoquímicas como a estabilidade da hemoglobina para detecção de variantes instáveis. Na prática, as provas mais úteis são as que permitem detectar a presença de hemoglobinopatias, como acontece com a hemoglobina S deixando para laboratórios especializados aqueles procedimentos para identificar a mutação. Detectar corretamente os portadores das diferentes hemoglobinopatías visa a dar um conselho genético adequado sobre a forma de herança, o risco de ter filhos afetados com as formas graves da doença e evitar tratamentos desnecessários. O diagnóstico molecular se reserva para a alfa talassemia, para quadros com genótipos complexos, estudos pré-natais ou epidemiológicos.

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.

Bases moleculares de hemoglobinopatías en Argentina / Molecular basis of hemoglobinopathies in Argentina / Bases moleculares de hemoglobinopatias na Argentina

Durante el desarrollo de un individuo se expresan distintas cadenas de globina de tipo a y no-a, que se combinan en tetrámeros para formar hemoglobina. Los genes que las codifican se organizan en familias. Distintas mutaciones afectan los genes que codifican las cadenas de globina: si provocan alteraciones cualitativas originan cuadros de hemoglobinopatías estructurales, si disminuyen las síntesis de las cadenas de globina, talasemias, y si tienen ambos efectos, hemoglobinopatías talasémicas. El propósito de este trabajo es presentar las bases moleculares de las hemoglobinopatías en Argentina, en un total de 862 muestras, en base a los estudios moleculares realizados en este laboratorio a partir del estudio de 910 muestras de pacientes. En nuestro medio, la Hb S es la hemoglobinopatía estructural más frecuente, las ß-talasemias presentan una distribución similar a la cuenca del Mediterráneo y las a-talasemias están intrínsecamente relacionadas a la ascendencia de los afectados. Las bases moleculares de las hemoglobinopatías son variadas. Mientras que en las hemoglobinopatías estructurales y ß-talasemias predominan las mutaciones puntuales, en las a-talasemias predominan las deleciones. Se describen mutaciones nóveles (cambios puntuales, deleciones y duplicaciones) que se presentan como eventos aislados con herencia recesiva o dominante. Es necesaria la interacción entre el médico hematólogo, el laboratorio bioquímico, el laboratorio molecular y el médico genetista, para llegar al diagnóstico certero de estos cuadros que permitirán reducir la incidencia de las formas severas.

Functional hemoglobin is a tetramer composed of 2 a and 2 non-a chains, encoded by genes that are organized in clusters and are expressed sequentially through development. There are multiple mutations described that affect these genes: if the sequence variant leads to a qualitative alteration, the resulting effect is a structural hemoglobinopathy, if it decreases the synthesis of the globin chains, thalassemia, and if it affects both the quality and quantity of the globin chain, the consequence is a thalassemic hemoglobinopathy. The aim of this paper is to present the molecular bases of hemoglobinopathies in Argentina, determined in 862 patients, based on the results of the molecular studies carried out in our laboratory from the analysis of 910 samples. Hb S is the most frequent structural hemoglobinopathy, ß-thalassemia mutations exhibit a pattern similar to the one displayed by Mediterranean basin populations, and a-thalassemia mutations are intrinsically related to the ancestry of those affected. These syndromes exhibit diverse molecular bases: structural hemoglobinopathies and ß-thalassemia are a consequence, mostly of point mutations, whereas in a-thalassemia deletions prevail. Novel mutations (point changes, deletions and duplications) that occurred as isolated events, with recessive or dominant inheritance, were described. Interaction between the hematologist, the geneticist and both the clinical and molecular biology laboratories is necessary to reach an accurate diagnosis of these syndromes and reduce the incidence of severe forms.

Durante o desenvolvimento de um indivíduo expressam-se diversas cadeias de globina de tipo a e não-a, que se combinam em tetrámeros para formar hemoglobina. Os genes que as codificam são organizados em famílias. Diferentes mutações afetam os genes que codificam as cadeias de globina: se provocarem alterações qualitativas originam quadros de hemoglobinopatias estruturais, se diminuírem as sínteses das cadeias de globina, talassemias, e se tiverem ambos os efeitos, hemoglobinopatias talassêmicas. O propósito deste trabalho é apresentar as bases moleculares das hemoglobinopatias na Argentina, num total de 862 amostras, com base nos estudos moleculares realizados neste laboratório a partir do estudo de 910 amostras de pacientes. No nosso meio, a Hb S é a hemoglobinopatia estrutural mais frequente, as ß-talassemias apresentam uma distribuição similar à bacia do Mediterrâneo e as a-talassemias estão intrinsecamente relacionadas com a ascendência dos afetados. As bases moleculares das hemoglobinopatias são variadas. Enquanto nas hemoglobinopatias estruturais e ß-talassemias predominam as mutações pontuais, nas a-talassemias predominam as deleções. Descrevem-se mutações incipientes (mudanças pontuais, deleções e duplicações) que se apresentam como eventos isolados com herança recessiva ou dominante. É necessária a interação entre o médico hematólogo, o laboratório bioquímico, o laboratório molecular e o médico geneticista, para chegar ao diagnóstico certo desses quadros que permitirão reduzir a incidência das formas severas.

Variantes de hemoglobina en una población con impresión diagnóstica positiva para hemoglobinopatías en Colombia / Hemoglobin variants in Colombian patients referred to discard hemoglobinopathies

Background: Oxygen transport is altered in hemoglobinopathies. Aim: To study the distribution of hemoglobinopathies in Andean subjects without African ancestry. Material and Methods: We analyzed blood samples of 1,407 subjects aged 18 to 59 years (58% females), living in the central Andean region of Colombia, referred to discard hemoglobinopathies. The frequency and type of hemoglobinopathy was established by capillary and agarose gel electrophoresis. Results: The frequency of hemoglobinopathies was 34.5% and higher among females. The structural variants found were: AS-heterozygous hemoglobin (8.1%), homozygous SS (3.7%), heterozygous SC (2.2%), AC heterozygotes (0.5%) and heterozygous AE (0.3%). Quantitative variants found were Hb A-Beta thalassemia (13.91%) and Hb H (0.06%), Beta-thalassemia heterozygotes C (0.88%), S-Beta thalassemia heterozygotes (6.07%) and compound heterozygous SC/Beta thalassemia (0.25%), with a persistence of fetal hemoglobin 0. Composite thalassemia was also found in 31%. All techniques showed good correlation and capillary electrophoresis demonstrated a greater detection of hemoglobin variants. Conclusions: The frequency of hemoglobin variants in the analyzed population was high, which is an important public health indicator. The most common hemoglobin variant was HbA/Increased structural Hb A2 and the mos frequent structural hemoglobinopathy was sickle cell trait. Capillary electrophoresis can discern any Hb variants present in the population.

Hemoglobin D-Punjab: origin, distribution and laboratory diagnosis

This review discusses hemoglobin D-Punjab, also known as hemoglobin D-Los Angeles, one of the most common hemoglobin variants worldwide. It is derived from a point mutation in the beta-globin gene (HBB: c.364G>C; rs33946267) prevalent in the Punjab region, North-western Indian. Hemoglobin D-Punjab can be inherited in heterozygosis with hemoglobin A causing no clinical or hematological alterations, or in homozygosis, the rarest form of inheritance, a condition that is commonly not related to clinical symptomatology. Moreover, this variant can exist in association with other hemoglobinopathies, such as thalassemias; the most noticeable clinical alterations occur when hemoglobin D-Punjab is associated to hemoglobin S. The clinical manifestations of this association can be similar to homozygosis for hemoglobin S. Although hemoglobin D-Punjab is a common variant globally with clinical importance especially in cases of double heterozygosis, hemoglobin S/D-Punjab is still understudied. In Brazil, for example, hemoglobin D-Punjab is the third most common hemoglobin variant. Thus, this paper summarizes information about the origin, geographic distribution, characterization and occurrence of hemoglobin D-Punjab haplotypes to try to improve our knowledge of this variant. Moreover, a list of the main techniques used in its identification is provided emphasizing the importance of complementary molecular analysis for accurate diagnosis.

Follow-up of children with hemoglobinopathies diagnosed by the Brazilian Neonatal Screening Program in the State of Pernambuco

OBJECTIVE: To determine the geographical distribution of hemoglobinopathies in the State of Pernambuco, to characterize the children with these diseases and to describe factors associated with their follow-up at the referral center during the period from 2003 to 2010. METHODS: A retrospective, cross-sectional, descriptive study was carried out of 275 medical records from a total of 302 children with hemoglobinopathies diagnosed by the National Neonatal Screening Program in the State of Pernambuco in the study period. Microsoft Excel was used for data processing and analysis. The chi-square and the Fisher test were used for statistical analysis. The level of significance was set at 5%. Terra View software was used to analyze the geographical distribution of hemoglobinopathies in the State. RESULTS: A total of 8.9% of the cases of hemoglobinopathies detected in the period were not followed up at the referral center. For the mothers of children with diseases, this was their second or third or more pregnancy in 64.2% and 30.2%, respectively. Regarding the influence of region of residence and regular medical appointments, the study demonstrated that children from the Zona da Mata, Sertão and Vale do São Francisco regions did not attend 45.2%, 50% and 55.6% of their appointments in the outpatient department, respectively. CONCLUSIONS: This study shows that a significant number of children do not begin consultations in the outpatient clinic and even those who started treatment early and who have the most severe form of the disease, usually miss medical appointments...

Guidelines for screening, diagnosis and management of hemoglobinopathies.

The b‑thalassemias and sickle cell disorders are a major health burden in India. Diagnosis and management of these disorders both in adults and in newborns using appropriate approaches and uniform technology are important in different regions of a vast and diverse country as India. In view of a National Thalassemia Control Program to be launched soon, a need was felt for guidelines on whom to screen, cost‑effective technologies that are to be used as well as for establishing prenatal diagnosis programs in regional centers. Newborn screening for sickle cell disorders is in its infancy in India and uniform approaches need to be followed. Also, included are guidelines for monitoring and managing patients who are now growing older and need comprehensive care as well as management of complications of the disease.

Analysis of hemoglobin electrophoresis results and physicians investigative practices in Saudi Arabia.

BACKGROUND AND OBJECTIVES: Riyadh and central province falls in a moderate prevalent zone of hemoglobinopathies in Saudi Arabia. However, it has been observed that the physicians working in Saudi Arabia invariably advise all cases of anemia for hemoglobin electrophoresis (HE). The present work was carried out to study the yield of the HE in Riyadh and the investigative practices of the physicians advising HE. SETTINGS AND DESIGN: The study was carried out in the hospitals of King Saud University from 2009 to 2011 in order to assess the yield of HE in referred cases of clinical anemia. MATERIALS AND METHODS: A total of 1073 cases divided in two groups of males and females had undergone complete blood count and red blood cell morphology. Cellulose acetate HE was performed and all the positive results were reconfirmed on the high performance liquid chromatography (HPLC). The results were analyzed for the type of hemoglobinopathies. For statistical analysis Statistical Package for Social Sciences 15 version (SPSS Inc., Chicago, IL, USA) was used. RESULTS: A total of 405 males and 668 females blood samples were included in the present study. 116 (28.5%) males and 167 (25%) females showed an abnormal pattern on HE. The incidence of beta thalassemia trait was higher in females while sickle cell trait was predominantly seen in males. Red cell indices were reduced considerably in thalassemias, but were unaffected in sickle cell disorders, except those which had concurrent alpha trait. The total yield of HE was 26.6% which was much less than expected. CONCLUSION: The physicians are advised to rule out iron deficiency and other common causes of anemia before investigating the cases for hemoglobinopathies, which employs time consuming and expensive tests of HE and HPLC.

Hemoglobin E disorder: Newborn screening program.

Hemoglobin E (Hb E) disorder is an important kind of hemoglobinopathy. It can be seen around the world with the highest prevalence in Southeast Asia. The screening for this disorder becomes the public health policies in many countries. The screening can be performed in several population groups. The newborn screening program for Hb E disorder is an important issue in pediatric genetics. In this brief review, the author discusses on important laboratory tests for screening for Hb E disorder in newborn.

Phenylketonuria, congenital hypothyroidism and haemoglobinopathies: public health issues for a Brazilian newborn screening program / Fenilcetonúria, hipotireoidismo congênito e hemoglobinopatias: questões de saúde pública para um programa de triagem neonatal brasileiro

In this study, the frequency of detected congenital hypothyroidism, phenylketonuria and haemoglobinopathies in the State of Rio de Janeiro's (Brazil) Newborn Screening Program (NBSP) was analyzed between the years of 2005 and 2007. There were two Newborn Screening Reference Centers (named NSRC A and B) with programmatic differences. In 2007, overall detection coverage reached 80.7%. The increase in the incidence of congenital hypothyroidism (1:1,030 in 2007) was attributed to the reduction of neonatal TSH value limits over time. The incidence discrepancy of phenylketonuria between NSRC A (1:28,427) and B (1:16,522) might be partially explained by the small number of cases. The incidence of sickle cell disease and its traits were uniformly high (1:1,288 and 1:21, respectively). This was coherent with the ethnic composition of the population. The differences in laboratory methods and critical values, in addition to other programmatic issues, may explain the variances in the results and limited analysis of the role of biological and environmental determinants in the occurrence of these diseases.

Neste estudo, foi analisada a frequência de detecção do hipotireoidismo congênito, fenilcetonúria e hemoglobinopatias no Programa de Triagem Neonatal do Estado do Rio de Janeiro, Brasil, entre 2005 e 2007. Havia dois Serviços de Referência em Triagem Neonatal (designados SRTN A e B) com diferenças programáticas. Em 2007, a cobertura alcançou 80,7%. O aumento na incidência do hipotireoidismo congênito (1:1.030 em 2007) foi atribuído à redução no valor de corte do TSH ao longo do tempo. As incidências discrepantes da fenilcetonúria entre os modelos (SRTN A - 1:28.427; SR-TN B - 1:16.522) podem ser parcialmente explicadas pelo pequeno número de casos. A incidência da doença falciforme e do traço falcêmico foi uniformemente elevada (1:1.288 e 1:21, respectivamente), sendo coerente com a composição étnica da população. As diferenças nos métodos laboratoriais e valores críticos, além de outras questões programáticas, podem explicar a variabilidade nos resultados e limitar a análise do papel dos determinantes biológicos e ambientais sobre a ocorrência das doenças.

Técnicas electroforéticas en el HYDRASYS 2. Utilidad diagnóstica en diferentes enfermedades / Electrophoretic techniques in HYDRASYS 2. Diagnostic usability in different diseases

Se presentan los resultados de la estandarización de las técnicas de electroforesis de hemoglobina (Hb), isoenzimas de la deshidrogenasa láctica (LDH) y proteinuria en el equipo Hydrasys 2, así como el estudio de pacientes atendidos en el Instituto de Hematología e Inmunología y en otros centros hospitalarios del país. Se realizó el diagnóstico de 149 portadores de hemoglobinopatías (AS, AC, b talasemia heterocigótica, variante rápida), 60 enfermos (SS, SC, CC), 24 pacientes con a talasemia o deficiencia de hierro y se cuantificó la hemoglobina fetal a 93 casos con hemoglobinopatía S. Se determinaron los valores normales de actividad e isoenzimas de LDH en la población mediante el estudio de 50 donantes de sangre. En los pacientes con anemia drepanocítica se encontró un aumento significativo de la isoenzima 1 (p= 0,000) y disminución de isoenzimas 3 (p= 0,002). Se realizó el estudio de proteínas en orina a 8 pacientes con enfermedades hematológicas que presentaron microalbuminuria al menos en 2 ocasiones, con concentraciones ³ 0,04 g/L. En 2 pacientes el resultado fue normal; en 2 se encontraron proteínas de origen tubular; y en otros 2, proteínas de origen glomerular

We present the results of the standardization of the techniques of electrophoresis of hemoglobin (Hb), lactate dehydrogenase isoenzymes (LDH) and proteinuria in HYDRASYS 2 equipment, and the study of patients treated at the Institute of Hematology and Immunology and other hospitals in the country. 149 hemoglobinopathies carriers were diagnosed (AS, AC, b thalassemia heterozygous fast variant), 60 patients (SS, SC, CC), 24 patients with athalassemia or iron deficiency. Fetal hemoglobin was quantified in 93 cases with hemoglobinopaty S. Normal values of activity and LDH isoenzymes were determined in the population through the study of 50 blood donors. In patients with sickle cell anemia we found a significant increase in isoenzyme 1 (p=0.000) and isozyme 3 decreased (p=0.002). We performed the study of proteins in urine in 8 patients with hematologic malignancies who had microalbuminuria at least 2 times, with concentrations ³ 0.04 g / L. In 2 patients the results were normal, in 2 proteins were tubular origin, and in 2, proteins of glomerular origin

A model of genetic guidance for hemoglobinopathy patients and laboratory diagnosis of family members as educational and preventive measures

BACKGROUND: The high frequency of hemoglobinopathies in Brazil constitutes a public health problem and thus educational and preventive measures are necessary to reduce the incidence. Genetic guidance, a modality of genetic counseling, and family screening are measures that can assist in reproductive decisions and mitigate clinical, psychological and social problems of families with these disorders. OBJETIVE: The objective of the current study was to evaluate the effectiveness of educational and preventive measures for hemoglobinopathies using genetic guidance and laboratory screening of families. METHODS: The diagnoses of patients with hemoglobinopathies were confirmed and then the level of knowledge about their disease was evaluated and genetic guidance was provided. Three months later, the level of assimilated information of these patients was evaluated. In addition, laboratory diagnosis of family members was carried out. RESULTS: Diagnosis of sickle cell anemia was confirmed for most patients. Moreover, the majority of the patients who had a low level of knowledge before genetic guidance (68.8%) demonstrated a higher level of assimilated information after the process (81.8%). Almost 70% of the family members had hemoglobin changes and some had hemoglobinopathies (2.6%). They were duly informed about the results of the examinations, which made it possible to investigate further. CONCLUSION: Genetic guidance and family screening were effective preventive and educational measures that improved the quality of life of patients, preventing complications and sequels and allowed the referral of those who may transmit altered genes for clinical diagnosis and to genetic counseling services.

Ethical issues in genetic counselling with special reference to haemoglobinopathies.

Genetic counselling is provided in places where genetic tests are carried out. The process involves pre-test counselling as well as post-test counselling to enable the individuals to face the situation and take appropriate decisions with the right frame of mind. Major ethical principles which govern the attitudes and actions of counsellors include: respect for patient autonomy, non-maleficence, beneficence, or taking action to help benefit others and prevent harm, both physical and mental, and justice, which requires that services be distributed fairly to those in need. Other moral issues include veracity, the duty to disclose information or to be truthful, and respect for patient confidentiality. Nondirective counselling, a hallmark of this profession, is in accordance with the principle of individual autonomy. High prevalence of haemoglobinopathies with availability of good and sensitive carrier detection tests and prenatal diagnostic techniques makes these good candidates for population screening of carriers along with genetic counselling for primary prevention of the disease. Screening of the extended family members of the affected child, high risk communities and general population screening including antenatal women are the main target groups for planning a Haemoglobinopathy control programme. A critical mass of trained genetic counsellors who have understanding of the ethical issues and its appropriate handling with the required sensitivity is needed in India.

Abnormal haemoglobins: detection & characterization.

Haemoglobin (Hb) abnormalities though quite frequent, are generally detected in populations during surveys and programmes run for prevention of Hb disorders. Several methods are now available for detection of Hb abnormalities. In this review, the following are discussed: (i) the methods used for characterization of haemoglobin disorders; (ii) the problems linked to diagnosis of thalassaemic trait; (iii) the strategy for detection of common Hb variants; and (iv) the difficulties in identification of rare variants. The differences between developing and industrialized countries for the strategies employed in the diagnosis of abnormal haemoglobins are considered. We mention the limits and pitfalls for each approach and the necessity to characterize the abnormalities using at least two different methods. The recommended strategy is to use a combination of cation-exchange high performance chromatography (CE-HPLC), capillary electrophoresis (CE) and when possible isoelectric focusing (IEF). Difficult cases may demand further investigations requiring specialized protein and/or molecular biology techniques.

Transfusion-induced hemoglobinopathy in patients of beta-thalassemia major.

Apparent hemoglobinopathy acquired after blood transfusion is an uncommon cause of diagnostic dilemma resulting in repeated testing and delay in the diagnosis. Out of the 1530 hemoglobin (Hb)- high-performance liquid chromatography (HPLC) performed at our hospital (May 2009 to April 2010), 3 pediatric cases of thalassemia major were detected having posttransfusion hemoglobinopathy with HbS ranging from 9.9% to 18.5%. In all three cases, there was no variant hemoglobin in earlier documented Hb-HPLC. It is important to be aware of and consider apparent transfusion-induced hemoglobinopathy in patients with unusual percentage of variant hemoglobin to avoid unnecessary treatment and counseling.

O laboratório clínico na investigação dos distúrbios da hemoglobina / The clinical laboratory in the investigation of hemoglobin disorders

As alterações na síntese da hemoglobina resultam em um grupo de distúrbios hereditários, os quais podem ser classificados como hemoglobina variante, se a alteração tiver origem em uma mutação no gene da hemoglobina, produzindo cadeias anormais, ou como talassemias, se a estrutura é normal, porém a síntese ocorre em quantidade alterada. Este trabalho tem como objetivo descrever a condução do diagnóstico laboratorial de quatro casos de distúrbios da hemoglobina, a fim de ilustrar o papel do laboratório e discutir o papel do patologista clínico como elemento de elo entre a clínica e o laboratório no processo de elucidação diagnóstica.

Defective synthesis of hemoglobin gives rise to a group of hereditary disorders. If the defect arises from a genetic mutation producing abnormal protein chains, the condition is classified as hemoglobin variant. Whereas, if the structure is normal but the synthesis is reduced, they are denominated as thalassaemia. This article aims to describe the laboratory diagnostic approach in four cases of hemoglobin disorders in order to illustrate the role of laboratories and discuss the role of clinical pathologists as a link between physicians and laboratories in diagnostic clarification.