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The phenomena of balanced effect between ?-globin gene and of ?-globin gene.

ABSTRACT: BACKGROUND:Thalassemias (TM) are the most common autosomal recessive disorders in Southeast Asian countries. Both ?- and ?-thalassemia lead to a decrease or absence of globin chains. The most serious of the thalassemia syndromes is thalassemia major which is characterized by a transfusion dependent anemia and subsequent iron overload caused by repeated blood transfusions. It is preventive by genotyping the parents. A better understanding of the laboratory data will help provide an accurate diagnosis of thalassemia major, and prevention and controlling programs in routine laboratories. CASE PRESENTATION:The patient was a one-year-old boy born to non-consanguineous parents. He was referred to our outpatient clinic for hemolytic anemia after a cold. Hematological investigations revealed severe anemia (Hb57 g/dL). The red cells displayed microcytosis, hypochromia and misshapen erythrocytes (MCV48.8 fL, MCH15.7 pg). Capillary electrophoresis (CE) electropherogram revealed normal level of HbA2 (3.2%) and elevated HbF (35.1%). The patient was diagnosed with ?-TM, based on severe microcytosis, hypochromia, normal Hb A2 and high Hb F level but no Hb H inclusion at the first visit. Later our molecular analysis revealed compound heterozygosity for codons 41-42 (-TTCT) (HBB: c.126_129delCTTT, ?0) and IVS-II-654 (C?>?T) (HBB: c.316-197C?>?T, ?+) mutation and deletional Hb H (--SEA/-?3.7). Thus, a combination of Hb H disease and a compound heterozygosity of ?+/?0-thalassemia (?+/?0-thal) was finally diagnosed. CONCLUSIONS:Genotype-phenotype analysis shows that heterozygous mutations in the ?-globin gene could affect not only hematological parameters, but also elevate HbA2 levels. These effects could be ameliorated by the coinheritance of Hb H disease, which may be explained by the phenomena of the ?-globin gene and of the ?-globin gene balanced effect.

SUBMITTER: Zhong L

PROVIDER: S-EPMC6098578 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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The phenomena of balanced effect between α-globin gene and of β-globin gene.

Zhong Liangying L Gan Xin X Xu Lingling L Liang Chujia C Xie Yingjun Y Lin Wenbin W Chen Peisong P Liu Min M

BMC medical genetics 20180817 1

<h4>Background</h4>Thalassemias (TM) are the most common autosomal recessive disorders in Southeast Asian countries. Both α- and β-thalassemia lead to a decrease or absence of globin chains. The most serious of the thalassemia syndromes is thalassemia major which is characterized by a transfusion dependent anemia and subsequent iron overload caused by repeated blood transfusions. It is preventive by genotyping the parents. A better understanding of the laboratory data will help provide an accura ...[more]

PMID: 30119651

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Project description:BACKGROUND:The lancelet amphioxus (Cephalochordata) is a close relative of vertebrates and thus may enhance our understanding of vertebrate gene and genome evolution. In this context, the globins are one of the best studied models for gene family evolution. Previous biochemical studies have demonstrated the presence of an intracellular globin in notochord tissue and myotome of amphioxus, but the corresponding gene has not yet been identified. Genomic resources of Branchiostoma floridae now facilitate the identification, experimental confirmation and molecular evolutionary analysis of its globin gene repertoire. RESULTS:We show that B. floridae harbors at least fifteen paralogous globin genes, all of which reveal evidence of gene expression. The protein sequences of twelve globins display the conserved characteristics of a functional globin fold. In phylogenetic analyses, the amphioxus globin BflGb4 forms a common clade with vertebrate neuroglobins, indicating the presence of this nerve globin in cephalochordates. Orthology is corroborated by conserved syntenic linkage of BflGb4 and flanking genes. The kinetics of ligand binding of recombinantly expressed BflGb4 reveals that this globin is hexacoordinated with a high oxygen association rate, thus strongly resembling vertebrate neuroglobin. In addition, possible amphioxus orthologs of the vertebrate globin X lineage and of the myoglobin/cytoglobin/hemoglobin lineage can be identified, including one gene as a candidate for being expressed in notochord tissue. Genomic analyses identify conserved synteny between amphioxus globin-containing regions and the vertebrate ?-globin locus, possibly arguing against a late transpositional origin of the ?-globin cluster in vertebrates. Some amphioxus globin gene structures exhibit minisatellite-like tandem duplications of intron-exon boundaries ("mirages"), which may serve to explain the creation of novel intron positions within the globin genes. CONCLUSIONS:The identification of putative orthologs of vertebrate globin variants in the B. floridae genome underlines the importance of cephalochordates for elucidating vertebrate genome evolution. The present study facilitates detailed functional studies of the amphioxus globins in order to trace conserved properties and specific adaptations of respiratory proteins at the base of chordate evolution.

Dataset Information

The phenomena of balanced effect between ?-globin gene and of ?-globin gene.

Publications

The phenomena of balanced effect between α-globin gene and of β-globin gene.

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