[Screening Results of Thalassemia and Analysis of Rare Genotypes]

To analyze the genotypes and distribution of thalassemia in Xindu District of Chengdu, in order to provide reference for the prevention and treatment of thalassemia in this area.

A total of 3 679 samples screened for thalassemia gene in Xindu District People's Hospital of Chengdu from June 2021 to April 2024 were selected as the study objects. Blood related parameters were detected by blood analyzer, hemoglobin composition was analyzed by capillary electrophoresis, and routine thalassemia gene detection was performed by PCR + flow-through hybridization. For the samples whose hematologic characteristics did not match the conventional results of thalassemia genes, the genotypes were determined by gene sequencing technology and the results were analyzed.

Among 3 679 samples, 540 carriers were detected, the total detection rate was 14.68%. Among them, 329 cases were α-thalassemia, with a total of 8 genotypes. The top 3 genotype in frequency were --^SEA/ αα (45.29%, 149/329), - α^3.7/ αα (38.91%, 128/329), and - α^4.2 / αα (6.08%, 20/329). There were 197 cases of β-thalassemia, with a total of 10 genotypes, and the top 3 genotype in frequency were β ^{CD41-42 (-TCTT)}/β ^N (29.95%, 59/197), β ^CD17(A>T)/β ^N (27.92%, 55/197), and β ^{IVSII-654(C>T)} /β ^N (24.87%, 49/197). There were 14 cases of αβ-thalassemia, with a total of 12 genotypes, and the main were - α^3.7/ αα, β ^{IVSII-654(C>T)} /β ^N and - α^3.7/ αα, β ^{CD41-42 (-TCTT)}/β ^N . There was a rare thalassemia genotype (--^SEA/ HKαα). In addition, three rare abnormal hemoglobin mutations and one unreported abnormal hemoglobin mutation (HBA1:c.300+13C>G site heterozygous mutation) were also found.

The detection rate of thalassemia gene in this area is high and the genotype is complex. In gene diagnosis, we should pay attention to the combination of multi-technology detection to avoid missing rare genotypes.