ABSTRACT
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.
Subject(s)
Humans , Female , Child , Hemoglobins, Abnormal/analysis , Hemoglobins, Abnormal/genetics , Hemoglobins, Abnormal/chemistry , Hemoglobinopathies/diagnosis , Hemoglobinopathies/genetics , Anemia , Oxygen , OximetryABSTRACT
Hemoglobinopathies are important inherited disorders with considerable high prevalence in Asia. Hemoglobin Q-India is a hemoglobinopathy that was first identified in India. Hb Q-India is caused by the mutation GAC --> CAC at codon 64 of the alpha-1 globin gene. The correlation between this hemoglobinopathy and thalassemia was reported. Although primary structure of disorder Hb Q-India is well documented, the secondary and tertiary structures, which can help explain the pathogenesis of the Hb Q-India disorder is not known. In this study, amino acid sequence of human alpha globin was searched using ExPASY and used for further mutation to Hb Q-India disorder. The derived sequences, alpha globin chains in both normal and Hb Q-India disorder, were used for further investigation for secondary and tertiary structures. Modeling of these proteins for secondary and tertiary structures was done using the NNPREDICT server and CPHmodels 2.0 Server, respectively. In this study, the secondary and tertiary structures of human alpha globin chains of normal and hemoglobin Q-India disorder are calculated and presented. Based on this information, the main difference between the predicted alpha globin secondary structures of normal and Hb Q-India is an extra helix in the Hb Q-India. The predicted tertiary structure also supports this finding. The results from this study can be good data for further study on Hb Q-India disorder, which can bring to the further understanding on this hemoglobinopathy.