Objective To study the influence of KLF1 gene mutations on fetal hemoglobin (Hb F) levels and their effects on thalassemia.

Methods Cases undergoing thalassemia screening at the First Affiliated Hospital of Guangxi Medical University from March 2023 to December 2024 were selected. Hb analysis and blood routine analysis were performed using a Hb analyzer and a blood cell analyzer. Sanger sequencing was used to detect KLF1 gene mutations and γ-globin gene promoter region mutations, while fluorescence PCR melting curve method and Gap-PCR were used to detect the genotypes of α- and β-thalassemia gene mutations.

Results Among 100 cases with elevated Hb F, 25 cases were detected with KLF1 gene mutations. Hb analysis showed that the Hb F levels in the 25 cases ranged from 4.9% to 75.9%, and the Hb A₂ levels ranged from 1.2% to 6.3%. Blood routine results showed that the Hb levels ranged from 63.4 g/L to 144.00 g/L, the red blood cell count (RBC) ranged from 1.90×10¹²/L to 6.48×10¹²/L, the mean corpuscular volume (MCV) ranged from 44.20 fL to 102.90 fL, and the mean corpuscular hemoglobin (MCH) ranged from 13.70 pg to 35.40 pg. Gene mutation analysis identified 5 types of KLF1 gene mutations, including c. 325 C > T heterozygote, c. 519-525dup CGGCGCC heterozygote, c.304T > C heterozygote and homozygote, c.1022G > A heterozygote, and c.939G > T heterozygote. Among the 25 cases, 14 cases were compounded with β-thalassemia and 7 cases were compounded with α-thalassemia.

Conclusion It is the first time in China that rare KLF1 gene mutations c.325 C > T and c.939G > T have been found to cause elevated Hb F levels, and they can alleviate the severity of anemia when combined with thalassemia. The KLF1 gene mutations c.519-525dup CGGCGCC, c.304T > C, and c.1022G > A have the same effects.