Abstract
The most common hemoglobin arose as an adaptation to the environment and its expansion was carried out by mechanisms of gene flow and population growth related to the social changes of habits of mankind. Other hemoglobinopathies (Hbs) to have low prevalence and appear in population studies of Hb or glycosylated hemoglobin (Hb A1c). Most of these Hbs have been identified in isolation and individually, others in a few families, considering these cases de novo mutations or that the mutated gene has been transported inadvertently. An example is Hb Nunobiki, discovered in Japan and Belgium. We report 7 cases from four families in Andalusia, identified during the quantification of Hb A1c. In all cases, both by capillary electrophoresis and ion exchange HPLC (II-HPLC), HBX appeared faster than HbA. By reverse phase HPLC eluted globin chain slower than αA, αX. Sequencing of gene α2 shown the substitution (CGT>TGT) in exon 3 CD141(Arg>Cys)→Hb Nunobiki. This hemoglobin has increased affinity for oxygen but was not detected by polycythemia due to the low percentage of variant since it is α chain, but because it showed during the determination of Hb A1c. This fact confirms that the II-HPLC is the gold standard for identification of hemoglobinopathies. The quantification of Hb A1c, by HPLC can identify structural Hb variants that otherwise would not have been detected and are clinically silent but may help clarify the evolution, adaptation and distribution of hemoglobin to the medium.
Highlights
Common hemoglobinopathies are those genetic alterations of the hemoglobin (Hb) whose prevalence rates exceed 1% of the population of any given region of the world
HbS, Hb C, Hb E, α thalassemia and β thalassemia are the most frequent monogenic disorders in the world and are an important public health issue. These common hemoglobinopathies seem to appear as an adaptation to the environment. Their populations of origin were subject to positive selection, because heterozygotes got protected against Plasmodium falciparum [1] malaria
The seven cases reported in Spain were located in the same region (Andalusia), and could all have their origin on the same gene mutation whose involuntary dispersion might be related to a specific event occurred at some point in the distant past
Summary
Common hemoglobinopathies are those genetic alterations of the hemoglobin (Hb) whose prevalence rates exceed 1% of the population of any given region of the world. HbS, Hb C, Hb E, α thalassemia and β thalassemia are the most frequent monogenic disorders in the world and are an important public health issue. These common hemoglobinopathies seem to appear as an adaptation to the environment. Their populations of origin were subject to positive selection, because heterozygotes got protected against Plasmodium falciparum [1] malaria. These genes are expanded by genetic drift mechanisms and driven by major events in human history. The development of agriculture and the subsequent appearance of the first human settlements contributed suitable conditions to consolidate malaria as a holoendemic disease, as well as the endemicity of the genes of these hemoglobinopathies [2]
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