The first Chinese with Hb Chile leading to chronic anemia and methemoglobinemia: a case report.

BACKGROUND: Hemoglobin (Hb) Chile [ß28(B10) Leu > Met; HBB: c.85 C > A] is a rare hemoglobin variant caused by a missense mutation in the HBB gene. Only one case of Hb Chile has been reported worldwide so far. It is an unstable hemoglobin, characterized by cyanosis associated with chronic methemoglobinemia and hemolytic anemia induced by sulfonamides or methylene blue. CASE PRESENTATION: A 9-year-3-month-old girl had mild anemia of unknown etiology for more than 6 years. She had a slight pallor without other symptoms or signs. The complete blood count revealed normocytic normochromic anemia with a sometimes-elevated reticulocyte count, and the bone marrow cytology showed marked erythroid hyperplasia, but the tests related to hemolysis were normal. Therefore, the whole exome sequencing was performed and showed a heterozygous mutation for HBB: c.85 C > A. With asymptomatic methemoglobinemia confirmed later, she was eventually diagnosed with Hb Chile. CONCLUSIONS: This is the first report of Hb Chile in China and the second worldwide. This case shows that Hb Chile is clinically heterogeneous and difficult to diagnose and expands our understanding on the clinical and hematological traits of the disease.

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.

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

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.

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.

Newborn screening for abnormal haemoglobins in Jamaica: Practical issues in an island programme.

OBJECTIVE: To report the diagnostic challenges of newborn screening for abnormal haemoglobins. SETTING: Cord blood samples from 13 hospitals in southwest Jamaica taken in 2008-2019. METHODS: Blood spots, collected from the umbilical cord, were analysed by high pressure liquid chromatography (HPLC) to reveal phenotypes for HbSS and HbCC, but genotype confirmation may require parental studies or gene sequencing. Such cases that were successfully traced were analysed in this follow-up study. RESULTS: HPLC screening of 121,306 samples detected HbAS in 11,846 (9.8%), HbAC in 4508 (3.7%) and other electrophoretic abnormalities in 1090 babies. Among 101 previously unconfirmed cases, 34/90 (38%) with HPLC evidence of a HbSS phenotype had other genotypes, and 7/11 (64%) with a HbCC phenotype had other genotypes. Syndromes from the interaction of ß thalassaemia occurred in 112 babies (85 with HbS, 27 with HbC) and of genes for hereditary persistence of fetal haemoglobin (HPFH) in 18 (12 with HbS, 6 with HbC). Variants other than HbS and HbC occurred in 270 babies, 16 in combination with either HbS or HbC, and 254 as traits. Most variants are benign even when inherited with HbS, although HbO Arab, HbD Punjab, or Hb Lepore Washington, which occurred in 6 cases, may cause sickle cell disease. CONCLUSIONS: Genes for ß thalassaemia and HPFH are common in western Jamaica and when associated with HbS may present diagnostic challenges in newborns, as HbF and HbA2 have not reached diagnostic levels. Family and DNA studies may be necessary for genotype confirmation.

Incidence of hemoglobinopathies and spatialization of newborns with sickle cell trait in Mato Grosso do Sul, Brazil.

OBJECTIVE: To evaluate the incidence of variant hemoglobins of newborn samples from the Neonatal Screening Center in the state of Mato Grosso do Sul, Brazil, and to analyze the distribution and spatial autocorrelation of newborns with sickle cell trait. METHODS: Samples from 35,858 newborns screened by the Neonatal Screening Center. The samples with inconclusive diagnosis were submitted to electrophoretic, chromatographic, cytological and molecular analyses. The spatial distribution analysis of newborns with sickle cell trait was performed by spatial autocorrelation. RESULTS: A total of 919 newborns showed an abnormal hemoglobin profile; in that, ten genotypes had significant clinical impacts identified. Among the asymptomatic newborns, the sickle cell trait was the most frequent (incidence of 1.885 cases/100 newborns). The highest incidence rates were registered in the municipalities of Terenos, Figueirão, Corguinho and Selvíria. There was positive spatial autocorrelation between the proportion of declared individuals of black race/color and the incidence of newborns with sickle cell trait. CONCLUSION: The early diagnosis by neonatal screening and laboratory tests was very important to identify abnormal hemoglobin profiles and guide the spatial autocorrelation analysis of sickle cell trait newborns in Mato Grosso do Sul, serving as a support to anticipate health measures aimed to discuss efficient therapeutic behaviors and effective planning of municipalities with the greatest need for care, monitoring and orientations for affected families.

Prevalence and Utility of Low Mean Corpuscular Volume in Infants Admitted to the Neonatal Intensive Care Unit.

OBJECTIVE: To determine the prevalence of low mean corpuscular volume (MCV) in newborn infants admitted to the neonatal intensive care unit and to assess low MCV as a diagnostic test for alpha thalassemia. STUDY DESIGN: Retrospective analysis of all infants admitted to the neonatal intensive care unit between January 2010 and October 2018 for which a complete blood count was performed during the first 3 postnatal days. Infants with a low MCV were compared with those with a normal MCV. Infants with positive hemoglobin Bart (Hb Bart) were compared with those withnegative Hb Bart. Low MCV was also evaluated as a diagnostic test for alpha thalassemia. RESULTS: A total of 3851 infants (1386 preterm, 2465 term) met the inclusion criteria and 853 (22.2%) had a low MCV. A low MCV was more common in term (25%) compared with preterm infants (17.1%, P < .001). Hb Bart positive newborn screening was identified in 133 infants (3.5%). Hb Bart was positive in 11.1% of infants with low MCV compared with 1.3% with normal MCV (P < .001). The sensitivity, specificity, positive predictive value, and negative predictive value of low MCV for the diagnosis of alpha thalassemia were 71.4%, 79.6%, 11.3%, and 98.7%, respectively. CONCLUSIONS: As Hb Bart positive newborn screens were seen in only 11.1% of infants with microcytosis, further diagnostic investigation may be warranted in individual infants. Further research to correlate microcytosis with iron status in infants and mothers is needed as well as studies using DNA analysis for the evaluation of alpha thalassemia variants.

Characterization of Recombinant His-Tag Protein Immobilized onto Functionalized Gold Nanoparticles.

The recombinant polyhistidine-tagged hemoglobin I ((His)6-rHbI) from the bivalve Lucina pectinata is an ideal biocomponent for a hydrogen sulfide (H2S) biosensor due to its high affinity for H2S. In this work, we immobilized (His)6-rHbI over a surface modified with gold nanoparticles functionalized with 3-mercaptopropionic acid complexed with nickel ion. The attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) analysis of the modified-gold electrode displays amide I and amide II bands characteristic of a primarily α-helix structure verifying the presence of (His)6-rHbI on the electrode surface. Also, X-ray photoelectron spectroscopy (XPS) results show a new peak after protein interaction corresponding to nitrogen and a calculated overlayer thickness of 5.3 nm. The functionality of the immobilized hemoprotein was established by direct current potential amperometry, using H2S as the analyte, validating its activity after immobilization. The current response to H2S concentrations was monitored over time giving a linear relationship from 30 to 700 nM with a corresponding sensitivity of 3.22 × 10-3 nA/nM. These results confirm that the analyzed gold nanostructured platform provides an efficient and strong link for polyhistidine-tag protein immobilization over gold and glassy carbon surfaces for a future biosensors development.

Quando a HbA1c não é suficiente: um caso de Hemoglobina de Baltimore / When HbA1c is not enough: a case of Baltimore Hemoglobin / Cuando la HbA1c no es suficiente: un caso de Hemoglobina de Baltimore

A hemoglobina A1c (HbA1c) é o gold standard para monitorização da diabetes mellitus. A HbA1c pode estar falsamente diminuída ou aumentada em algumas situações clínicas, como hemoglobinopatias, não traduzindo adequadamente o controle glicêmico. Apresenta-se aqui o caso de um doente com valor de HbA1c incompatível com os registros de glicemia capilar, devido à presença de hemoglobina N-Baltimore. O caso apresentando é relevante porque, apesar de assintomática, a presença desta hemoglobinopatia conduz a uma diabetes falsamente encarada como controlada, se utilizados os métodos de determinação de HbA1c habituais.

The haemoglobin A1c (HbA1c) test is the gold standard in monitoring diabetes mellitus. HbA1c can be falsely decreased or increased in some particular scenarios, as in hemoglobinopathies, inadequately reporting the glycemic control. Here we present the case of a patient with a HbA1c value incompatible with self-monitoring blood glucose levels, due to the presence of hemoglobin N-Baltimore. This case is relevant because, in spite of being asymptomatic, the presence of this type of hemoglobin leads to an incorrect appearance of glycemic control, if standard methods for HbA1c determination are used.

La hemoglobina A1c (HbA1c) es el estándar de oro para la monitorización de la diabetes mellitus. La HbA1c puede estar falsamente disminuida o aumentada en algunas situaciones clínicas, como hemoglobinopatías, no traduciendo adecuadamente el control glucémico. Se presenta aquí el caso de un paciente con valor de HbA1c incompatible con los registros de glucemia capilar, debido a la presencia de hemoglobina N-Baltimore. El caso que presenta es relevante porque, a pesar de asintomática, la presencia de esta hemoglobinopatía conduce a una diabetes falsamente encarada como controlada, si se utilizan los métodos de determinación de HbA1c habituales.

Thalassemia major phenotype caused by HB Zürich-Albisrieden [α2 59(E8) Gly > Arg (HBA2:C.178G > C)] in a Brazilian child.

Hemoglobin (Hb) Zürich-Albisrieden (ZA) [α2 59(E8) Gly > Arg; HBA2:c.178G > C] is a rare and highly unstable α-chain variant. A few simple and compound heterozygotes (αZA α/αα and -/αZA α, respectively) have been described so far in Switzerland and China. We describe here a case of homozygosity for the Hb ZA mutation (αZA α/αZA α) in a Brazilian child with severe congenital hemolytic anemia and ineffective erythropoiesis.

Two novel unstable hemoglobin variants due to in-frame deletions of key amino acids in the ß-globin chain.

Hemoglobinopathies are the most common autosomal recessive disorders and are mostly inherited in a recessive manner. However, certain mutations can affect the globin chain stability, leading to dominant forms of thalassemia. The aim of this work was the molecular and structural characterization of two heterozygous in-frame deletions, leading to ß-globin variants in pediatric patients in Argentina. The HBB gene of the probands and their parents was sequenced, and other markers of globin chain imbalance were analyzed. Several structural analyses were performed, and the effect of the mutations on the globin chain stability was analyzed. In Hb JC-Paz, HBB:c.29_37delCTGCCGTTA (p.Ala10_Thr12del), detected in an Argentinean boy, one α-helix turn is expected to be lost. In Hb Tavapy, HBB:c.182_187delTGAAGG (p.Val60_Lys61del), the deleted residues are close to distal histidine (His63) in the heme pocket. Both mutations are predicted to have a destabilizing effect. The development of computational structural models and bioinformatics algorithms is expected to become a useful tool to understand the impact of the mutations leading to dominant thalassemia.

The Results of Hemoglobin Variant Analysis in Patients Revealing Microcytic Erythrocytosis on Complete Blood Count.

BACKGROUND: Microcytic erythrocytosis is an underrecognized and underevaluated complete blood count (CBC) finding. The literature pertaining to the determination of its etiology specifically by hemoglobin variant analysis is limited. METHODS: We performed hemoglobin variant analysis by high performance liquid chromatography on 137 patients who revealed microcytic erythrocytosis on CBC, and reviewed the results for the diagnosis of hemoglobin-associated disorders. RESULTS: A diagnosis of thalassemia trait and/or a hemoglobinopathy was established in 93 of 137 (67.9%) patients. Amongst these, ß-thalassemia trait topped the list with 69 cases (74.1%), followed by hereditary persistence of fetal hemoglobin with 5 cases (5.5%), Hemoglobin E disease with 4 cases (4.3%), and ∂/ß-thalassemia with 2 cases (2.1%). Compound heterozygous conditions with 1 or more hemoglobinopathies and/or thalassemias were diagnosed in 13 cases (14.0%). Abnormal hemoglobins in the compound heterozygosity group included C, S, HPFH, and 2 unknowns. CONCLUSION: Hemoglobin variant analysis provided a very high positive yield in determining the etiology of microcytic erythrocytosis.

Understanding the molecular basis of the high oxygen affinity variant human hemoglobin Coimbra.

Human hemoglobin (Hb) Coimbra (ßAsp99Glu) is one of the seven ßAsp99 Hb variants described to date. All ßAsp99 substitutions result in increased affinity for O2 and decreased heme-heme cooperativity and their carriers are clinically characterized by erythrocytocis, caused by tissue hypoxia. Since ßAsp99 plays an important role in the allosteric α1ß2 interface and the mutation in Hb Coimbra only represents the insertion of a CH2 group in this interface, the present study of Hb Coimbra is important for a better understanding of the global impact of small modifications in this allosteric interface. We carried out functional, kinetic and dynamic characterization of this hemoglobin, focusing on the interpretation of these results in the context of a growth of the position 99 side chain length in the α1ß2 interface. Oxygen affinity was evaluated by measuring p50 values in distinct pHs (Bohr effect), and the heme-heme cooperativity was analyzed by determining the Hill coefficient (n), in addition to the effect of the allosteric effectors inositol hexaphosphate (IHP) and 2,3-bisphosphoglyceric acid (2,3-BPG). Computer simulations revealed a stabilization of the R state in the Coimbra variant with respect to the wild type, and consistently, the T-to-R quaternary transition was observed on the nanosecond time scale of classical molecular dynamics simulations.

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.

Coinheritance of Hb Bristol-Alesha [ß67(E11)Val→Met; HBB: c.202G>A] and the α212 Patchwork Allele in a Brazilian Child with Severe Congenital Hemolytic Anemia.

Hb Bristol-Alesha [HBB: c.202G>A; ß 67 Val>Met] is a rare structural variant of hemoglobin (Hb) resulting from a GTG>ATG substitution at codon 67 of the ß-globin gene that leads to the replacement of valine by methionine in the corresponding position of the ß-globin chain. The methionine residue is subsequently modified to aspartic acid [ß67(E11)Val-Met→Asp], possibly by autoxidation mechanisms. This substitution prevents normal non-polar binding of Val67 to the heme group, resulting in molecular instability and severe hemolysis. We identified Hb Bristol-Alesha (in the heterozygous state), as the cause of severe congenital hemolytic anemia in an 11-month-old girl of mixed (native Indian and European) ethnic origin from the Midwestern region of Brazil, whose parents were clinically and hematologically normal. The mutation on the ß-globin gene was found to have been coinherited with the α212 patchwork allele.

Hemoglobin Variant Profiles among Brazilian Quilombola Communities.

Brazilian Quilombolas are communities composed of African-derived populations that have their territories guaranteed by the Brazilian Constitution. The present study investigated the hemoglobin (Hb) variants among these population groups. This study was conducted in a total of 2843 individuals of Brazilian Quilombola communities of the Bahia, Pará, and Piauí states. All the participants had their Hb profiles evaluated. The Hb S (HBB: c.20A>T) variant was described in all the studied localities. However, the individuals in Bahia State had the highest frequency of the Hb C (HBB: c.19G>A) variant; individuals from Piauí State had a higher frequency of the Hb D-Punjab (HBB: c.364G>C) variant compared to the other states, and individuals from Pará State only carried the Hb S variant. The present study revealed a specific distribution of Hb variants that could represent different waves of African influence in these Brazilian populations.

HbA1c levels in individuals heterozygous for hemoglobin variants.

OBJECTIVE:: To evaluate the levels of glycated hemoglobin (HbA1c) in patients heterozygous for hemoglobin variants and compare the results of this test with those of a control group. METHOD:: This was an experimental study based on the comparison of HbA1c tests in two different populations, with a test group represented by individuals heterozygous for hemoglobin variants (AS and AC) and a control group consisting of people with electrophoretic profile AA. The two populations were required to meet the following inclusion criteria: Normal levels of fasting glucose, hemoglobin, urea and triglycerides, bilirubin > 20 mg/dL and non-use of acetylsalicylic acid. 50 heterozygous subjects and 50 controls were evaluated between August 2013 and May 2014. The comparison of HbA1c levels between heterozygous individuals and control subjects was performed based on standard deviation, mean and G-Test. RESULTS:: The study assessed a test group and a control group, both with 39 adults and 11 children. The mean among heterozygous adults for HbA1c was 5.0%, while the control group showed a rate of 5.74%. Heterozygous children presented mean HbA1c at 5.11%, while the controls were at 5.78%. G-Test yielded p=0.93 for children and p=0.89 for adults. CONCLUSION:: Our study evaluated HbA1c using ion exchange chromatography resins, and the patients heterozygous for hemoglobin variants showed no significant difference from the control group.