Abstract
BackgroundDeletional hereditary persistence of fetal hemoglobin (HPFH)/δβ‐thalassemia and δ‐thalassemia are rare inherited disorders which may complicate the diagnosis of β‐thalassemia. The aim of this study was to reveal the frequency of these two disorders in Southwestern China.MethodsA total of 33,596 subjects were enrolled for deletional HPFH/δβ‐thalassemia, and positive individuals with high fetal hemoglobin (Hb F) level were diagnosed by multiplex ligation‐dependent probe amplification (MLPA). A total of 17,834 subjects were analyzed for mutations in the δ‐globin gene. Positive samples with low Hb A2 levels were confirmed by δ‐globin gene sequencing. Furthermore, the pathogenicity and construction of a selected δ‐globin mutation were analyzed.ResultsA total of 92 suspected cases with Hb F ≥5.0% were further characterized by MLPA. Eight different deletional HPFH/δβ‐thalassemia were observed at a frequency of 0.024%. In addition, 195 cases suspected to have a δ‐globin gene mutation (Hb A2 ≤2.0%) were characterized by molecular analysis. δ‐Globin gene mutation was found at a frequency of 0.49% in Yunnan. The pathogenicity and construction for a selected δ‐globin mutation was predicted.ConclusionScreening of these two disorders was analyzed in Southwestern China, which could define the molecular basis of these conditions in this population.
Highlights
Thalassemias are autosomal recessive disorders that result from reduced or absent synthesis of one or more of the hemoglobin chains
Deletional hereditary persistence of fetal hemoglobin (HPFH) and δβ‐thalassemia is a rare inherited condition that is characterized by increased Hb F, which results from deletions in the upstream silencer region of the γ‐globin genes or upregulation of the γ‐globin genes (Sankaran, Xu, & Orkin, 2010), as there is no competition from the expression of β‐ and δ‐globin genes
The testing for δ‐thalassemia traits was carried out using the following selection criteria: (a) Hb A2 levels at or below 2.0% (Hb A2 ≤ 2.0%) and (b) low levels of Hb A2 associated with a visible second Hb A2 fraction (Hassan, Harteveld, Bakker, & Giordano, 2014)
Summary
National Natural Science Foundation of China (81260415, 81860040, 81660022, 81860030, 81460678); Natural Science foundation of Yunnan Province (2017FE467[‐108], 2017FE467[‐122]); Academic Leader Programme of Health and Family Planning Commission of Yunnan province (D‐2017056); and Internal scientific Research Project of Clinical Genetics Institute of Yunnan Province (2016NS234)
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