Satthakarn S, Panyasai S. α-Globin mutations and Genetic Variants in γ-globin Promoters are Associated with Unelevated Hemoglobin F Expression of Atypical β
0-thalassemia/HbE.
Arch Med Res 2024;
55:103055. [PMID:
39029212 DOI:
10.1016/j.arcmed.2024.103055]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 06/29/2024] [Accepted: 07/08/2024] [Indexed: 07/21/2024]
Abstract
BACKGROUND
Excessive expression of hemoglobin F (HbF) is a characteristic feature and important diagnostic marker of β0-thalassemia/HbE disease. However, some patients may exhibit low-HbF levels, leading to misdiagnosis and precluding genetic counseling. The genetic factors influencing these differences in HbF expression in this atypical disease are not completely understood.
AIMS
To investigate determinants contributing to the non-elevation of HbF expression in β0-thalassemia/HbE disease.
METHODS
We studied 231 patients with β0-thalassemia/HbE confirmed by DNA analysis; classified them into the low-HbF (n = 62) and high-HbF (n = 169) groups; analyzed hematological parameters and hemoglobin levels in both groups; and characterized mutations in β- and α-globin genes and genetic variants in γ-globin promoters.
RESULTS
Both groups showed similar rates of type β0-thalassemia mutations but significantly different proportions of α-globin mutations: approximately 88.7% (95% confidence interval [CI] = 66.8-115.5) and 39.1% (95% CI = 30.2-49.7) in the low- and high-HbF groups, respectively. The results revealed single-nucleotide polymorphisms (SNPs) at -158 (C>T) in the Gγ-globin promoters and novel SNPs at the 5' untranslated region position 25 (G>A) in Aγ-globin promoters. The distribution of CC genotypes of the Gγ-globin promoter in the low-HbF group was significantly higher than that in the high-HbF group.
CONCLUSIONS
Cases with HbE predominance with low-HbF levels and undetectable HbA may not be as conclusive as those with homozygous HbE until DNA analysis is performed. Concomitant inheritance of α-thalassemia is an important inherent factor modifying HbF expression in a typical β0-thalassemia/HbE, and SNPs with the CC genotype in the Gγ-globin promoter may indicate unelevated HbF expression in patients with this disease.
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