[Prevalence and molecular analysis of β-thalassemia in children of Han ethnicity in Chongqing city].

OBJECTIVE

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

METHOD

A 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.

RESULT

Twenty-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.

CONCLUSION

Chongqing 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.