Rare β-globin gene poly A (AATAAA > AATAGA) mutation causes β-thalassemia

Objective To analyze the rare β-globin gene poly A (AATAAA > AATAGA) mutation that causes β-thalassemia, and provide a basis for clinical diagnosis and treatment.

Methods Patients undergoing thalassemia screening and diagnosis at the First Affiliated Hospital of Guangxi Medical University from October 2023 to December 2024 were collected. Blood routine and hemoglobin (Hb) analyses were performed on these patients. The fluorescence PCR melting curve assay (FCMA) was applied to detect common β-thalassemia gene mutations, while Sanger sequencing technique was used to detect unknown or rare β-thalassemia gene mutations.

Results A total of 282 cases of β-thalassemia heterozygotes were detected, including 2 cases with the rare β-globin gene poly A (AATAAA > AATAGA, HBB: c. +112 A > G) mutation. Their blood routine results showed that hemoglobin (Hb) was 130.00 g/L-135.00 g/L, mean corpuscular volume (MCV) was 61.90 fL-65.90 fL, mean corpuscular hemoglobin (MCH) was 19.20 pg-21.70 pg, mean corpuscular hemoglobin concentration (MCHC) was 311.00 g/ L-329.00 g/L, and hematocrit (HCT) was 0.41 l/L-0.42 L/L. Notably, MCV and MCH levels were decreased. The results of hemoglobin (Hb) analysis showed that the level of Hb A₂ was elevated, ranging from 4.6% to 4.9%. When this mutation combined with other β-thalassemia mutations, mild to moderate anemia was observed clinically.

Conclusion The rare β-globin gene poly A (AATAAA > AATAGA) mutation was first identified in China. It causes β⁺-thalassemia, and needs to be attached importance to clinical diagnosis and treatment, genetic counseling, and prenatal diagnosis.