Abstract:

Objective To analyze the genotype distribution of thalassemia in the population of Pidu District of Chengdu City，and to investigate the clinical significance of mean corpuscular volume（MCV）and mean corpuscular hemoglobin（MCH）levels in patients with different genotypes of thalassemia，in order to provide a reference for clinical consultation and the formulation of auxiliary diagnostic schemes for thalassemia. Methods A total of 1 293 patients undergoing thalassemia genotyping at the Traditional Chinese Medicine Hospital of Pidu District and the Maternal and Child Health Hospital of Chengdu Pidu District from March 2023 to August 2024 were enrolled. The thalassemia genotypes and red blood cell-related determination data were collected. The patients were classified into 3 age groups：0-18 years old，19-50 years old and >50 years old. The differences in MCV and MCH levels among the 3 groups were compared. The differences in MCV and MCH levels among patients with different genders and different types of thalassemia were compared. The auxiliary diagnostic efficacy of 3 auxiliary diagnostic criteria for thalassemia（MCV<78 fL and/or MCH<27 pg，MCV<80 fL and/or MCH<27 pg，MCV<82 fL and/or MCH<27 pg）was compared. Results Among the 1 293 patients，440 cases（34.03%）were diagnosed with thalassemia. Among them，208 cases（47.27%，with 10 genotypes）were α-thalassemia，and 225 cases（51.14%，with 13 genotypes）were β-thalassemia. Totally，7 cases（1.59%，with 5 genotypes）were α- + β-thalassemia. The MCV and MCH levels in non-thalassemia group were higher than those in thalassemia group，and those in α-thalassemia group was higher than those in β-thalassemia group. In α-thalassemia group，patients with the mutation type of --^SEA/-α^3.7 had the lowest MCV and MCH levels，while those with the mutation type of -α^3.7/αα had the highest MCV and MCH levels. In β-thalassemia group，patients with the CD43 mutation had the lowest MCV and MCH levels，and those with the βE mutation had the highest MCV and MCH levels. The MCV and MCH levels of female thalassemia patients were higher than those of male thalassemia patients（P<0.001）. The MCV and MCH levels were the lowest in 0-18 years old group and the highest in 19-50 years old group. The determination rate of the 3 auxiliary diagnostic criteria was 8.55%（33/386）. The determination rates of α-thalassemia，β-thalassemia，and α- + β-thalassemia with the 3 criteria were 63.64%，33.33% and 3.03%，respectively，and the undetermined populations were the same. The undetermined genotypes of α-thalassemia were mainly -α3.7/αα，αCS/αα and -α4.2/αα；the undetermined genotypes of β-thalassemia were mainly CD41-42，IVS-Ⅱ-654 and CD17；the undetermined genotypes of α- + β-thalassemia were CD41-42 combined with -α3.7/αα（100%）. The undetermined rate for male thalassemia patients was 21.21%，and that for female thalassemia patients was 78.79%. The determination rate was the highest in 19-50 years old group（60.61%）and the lowest in >50 years old group（3.03%）. Conclusions The thalassemia genotypes in Pixu District of Chengdu City are diverse，and β-thalassemia is slightly more common than α-thalassemia. Gender，age and genotypes all affect the MCV and MCH levels of thalassemia patients，and quiescent-type α-thalassemia，19-50-year-old patients are more likely to be missed.

Key words: Mean corpuscular volume, Mean corpuscular hemoglobin, Genotype, Thalassemia, Pidu District of Chengdu City