The gene spectrum of thalassemia in Yangjiang of western Guangdong Province

Front Genet. 2023 Feb 13:14:1126099. doi: 10.3389/fgene.2023.1126099. eCollection 2023.

Abstract

Background: Thalassemia presents a higher incidence in southern China. The objective of this study is to analyze the genotype distribution of thalassemia in Yangjiang, a western city of Guangdong Province in China. Methods: The genotypes of suspected cases with thalassemia were tested by PCR and reverse dot blot (RDB). Unidentified rare thalassemia genotypes of the samples were further ascertained by PCR and direct DNA sequencing. Results: Among 22467 suspected cases with thalassemia, 7658 cases were found with thalassemia genotypes using our PCR-RDB kit. Among these 7658 cases, 5313 cases were found with α-thalassemia (α-thal) alone, --SEA/αα was the most common genotype, accounting for 61.75% of α-thal genotypes, and the following mutations were found: α3.7/αα, -α4.2/αα, αCSα/αα, αWSα/αα, and αQSα/αα. A total of 2032 cases were found with β-thalassemia (β-thal) alone. βCD41-42N, βIVS-II-654N, and β-28N accounted for 80.9% of all β-thal genotypes, and the following genotypes were found: βCD17N, βCD71-72N, and βEN. Compound heterozygotes of β-thal and β-thalassemia homozygotes were identified in 11 and five cases, respectively, in this study. α-thal combined with β-thal was identified in 313 cases, showing 57 genotype combinations of the coincidence of both Hb disorders; one extreme patient had a genotype of --SEAWSα and βCD41-42-28. In addition, four rare α-mutations (--THAI, HKαα, Hb Q-Thailand, and CD31 AGG>AAG) and six rare β-mutations (CD39 CAG>TAG, IVS-Ⅱ-2 (-T), -90(C>T), Chinese Gγ+(Aγδβ)0, CD104 (-G), and CD19 A>G) were also found in this study population. Conclusion: This study provided detailed genotypes of thalassemia in Yangjiang of western Guangdong Province in China and reflected the complexity of genotypes in this high-prevalence region, and this would be valuable for diagnosis and counseling for thalassemia in this area.

Keywords: China; Guangdong Province; gene testing; genotype; thalassemia.

Grants and funding

This study was supported by the Natural Science Foundation of Guangdong Province (No. 2016A030307035) and High Level Development Plan of People’s Hospital of Yangjiang (Nos G2020007 and 2021007).