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

OBJECTIVE: To investigate the incidence and the gene mutation frequencies and patterns of ß-thalassemia (ß-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 ß-Thal screening indicators. The positive samples of screening indicators were detected and identified by PCR-reverse dot blot method for 18 common ß-Thal mutations in Chinese populations, unknown mutations samples were subjected to DNA sequencing analysis of the ß-globin gene. RESULT: Twenty-five cases of ß-Thal carriers were observed from the 1726 samples, with 24 cases of ß-Thal heterozygote and one case of double heterozygote. Therefore, the ß-Thal carrier rate was 1.51%. After 1726 peripheral venous blood samples analyzed by hematological parameters, 164 positive cases of ß-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 ß-Thal. Epidemiological Data from the research was useul for the genetic counseling and the prevention of ß-Thal major.

Prevalence and genetic analysis of α-thalassemia and ß-thalassemia in Chongqing area of China.

BACKGROUND AND AIMS: Thalassemia is one of the most common hereditary disorders. This study aimed to investigate the prevalence of thalassemia and the mutation spectrum in Chongqing, the southern area of China. METHODS: A total of 1057 children were recruited from Chongqing. Hematological parameters were examined and globin genes were genetically analyzed. RESULTS: The total frequency of thalassemia carriers was 7.76% in this group of children. Among these, α-thalassemia was 5.20%, ß-thalassemia was 1.99% and abnormal hemoglobin variant was 0.57%. Furthermore, 24 cases of α-triplication were detected, frequency of which was 2.55%. The true prevalence of silent α-thalassemia was first reported in this study. In addition, six novel mutations that give rise to α-thalassemia and two rare abnormal hemoglobin variants were first identified in Chinese population. CONCLUSIONS: Our data suggested that the population in Chongqing are at high risk of α- and ß-thalassemia. The findings will be useful for genetic counseling and the prevention of severe thalassemias in this area.