Screening results and genetic diagnosis of thalassemia in 8 024 cases in Chongqing region

Abstract:

Objective：To investigate the distribution of α-& β-thalassemia in Chongqing. Methods：Totally 8 024 samples from district and counties of Chongqing were detected for α-& β-thalassemia genotype using gap single polymerase chain reaction（GSPCR） com－bined with reverse dot blot hybridization（RDB）. Before the detection，red peripheral blood cell（RBC），hemoglobin（HB），mean cor－puscular volume（MCV），mean corpuscular hemoglobin（MCH），mean corpuscular hemoglobin concentration（MCHC），hemoglobin elec－trophoresis index in each set of sample were screened. In the 8 024 samples，1 267 were male and 6 757 were female. The sample aged from 0-91 years old and were divided into chil－dren group（0-16 years old，317 cases），adult group（17-49 years old，7 572 cases） and seniors group（50-91 years old，155 cases）. Results：1 117 cases of α- and β-thalassamia were detected out from the 802 4 cases，accounting for 13.92%. Among the 1 117 cases，479 were α-thalassamia. The most common mutations were as follows：--SEA/αα（332 cases），-α3.7/αα（84 cases） and -α4.2/αα（15 cases），accounting for 89.98%，69.31%，17.54% and 3.13% respectively. Deletion a-thalassaemia was the domain type，5 cases of --SEA/-α3.7 and 1 cases of --SEA/-α4.2. There were 42 cases of non-deletional alpha-thalassaemi，accounting for 8.76%. 619 cases were surly diagnosed as β-thalassamia and 19 cases were α-thalassemia composite β-thalassamia. 12 β-thalassamia genotypes were found，and the common constitutions of mutation were CD17（A→T）（the most common constitution），CD41—42（-TCTT），IVS-2-654（C→T），CD43，TATAboxnt -28（A→T），βE，accounting for 96.12%. There was 1 case CAP and 1 case IVS1-1. Among the 8 024 cases，167 male cases and female 950 cases were diagnosed as α-& β-thalassemia including 77 male cases and 402 female cases of α-tha－lassemia as well as 74 male cases and 545 female cases of β-thalassemia. The positive rate of α-& β-thalassemia was higher in fe－male than in male，but having no statistical significance（ χ2=0.691，P=0.433）. There was no statistical significance in detection rate of α-& β-thalassemia between male and female（ χ2=0.381，P=0.604）. Among all samples，317（33.75%） cases in children group，982（13.00%） cases in adult group and 155（18.06%） cases in senior group were diagnosed as thalassemia（ χ2=1.711，P=0.318），without statistical differences. Conclusions：--SEA/αα genotype and CD17（A→T） gene mutation is the most common type in α-thalassemia and β-thalassemia in Chongqing. However，the significant hazard in adult group concentrates in the breeding age. Thus to screen tha－lassemia genotype of adult in breeding age is of great significance in raising population quality.