OBJECTIVETo investigate the incidence and the gene mutation frequencies and patterns of β-thalassemia (β-Thal) in ethnic Han children in Chongqing city.

METHODA total of 1726 children were screened by using automatic hemocytic analyzer, cellulose acetate electrophoresis and fetal hemoglobin alkali denaturation test. Samples with mean corpuscular volume (MCV) < 80 fl, cell hemoglobin content (MCH) < 27 pg and hemoglobin A2 (HbA2) levels >3.3%, fetal hemoglobin (HbF) >2% for β-Thal screening indicators. The positive samples of screening indicators were detected and identified by PCR-reverse dot blot method for 18 common β-Thal mutations in Chinese populations, unknown mutations samples were subjected to DNA sequencing analysis of the β-globin gene.

RESULTTwenty-five cases of β-Thal carriers were observed from the 1726 samples, with 24 cases of β-Thal heterozygote and one case of double heterozygote. Therefore, the β-Thal carrier rate was 1.51%. After 1726 peripheral venous blood samples analyzed by hematological parameters, 164 positive cases of β-Thal screening indicators were found, with the positive rate being 9.50% (164/1726). A total of 6 different gene mutations were detected, the four most common mutations were as the following: CD41-42, IVS-II-654, CD17 and beta E. These four mutations as the major types in this area accounted for 88.00% of all the mutations. In addition, one rare mutation of 5 'UTR; + (43 -40) was found, and one case of the hemoglobin variant of Hb Zurich was reported in Chinese people for the first time.

CONCLUSIONChongqing is a high risk region of the β-Thal. Epidemiological Data from the research was useul for the genetic counseling and the prevention of β-Thal major.