Gene Analysis Of Beta-thalassemia Among Children In Luzhou City

Objective: Thalassemia is a single-gene hereditary and hemolyticanemia caused by globin synthesis imbalance which due to hemoglobin genemutation. There are two types of thalassemia:α-and β-thalassemia. It is themost common and the highest-incidence of hereditary hemolytic anemia in theworld, and is also one of the most serious hazards hemoglobinopathies. Abroadto the Mediterranean countries and Southeast Asian countries is more common,Guangdong, Guangxi, Hainan, Sichuan and other provinces (autonomousregions) are more common in China. This disease has a high degree of geneticheterogeneity and great geographical ethnic differences, so prevention anddiagnosis of these variations can provide a scientific basis for the disease. Thisresearch paper focuses on the gene mutation types and proportions of β-thalassemia in Luzhou area, as to provide a theoretical basis for the diagnosisand prevention of β-thalassemia in this region. As well as to discuss theimportance and significance of genetic diagnosis technique.Methods:1.Allcase sources have been collected from pediatric clinic (including child healthclinic) and child inpatient in the Affiliated Hospital of Luzhou Medical Collegeduring January2011to June2013.2.All patients underwent blood tests，screening of hemoglobin (Hb)<110g/L, mean corpuscular volume (MCV)<80fl, mean corpuscular hemoglobin (MCH)<27pg small cell hypochromicanemia in children further make hemoglobin electrophoresis.3.Hemoglobin electrophoresis results judged as positive for β-thalassemia phenotype, namelyMCV <80%, HbA2>3.2%or HbF>3.1%, carried β thalassemia gene detection.4.The common known17types mutation on β-globin gene were idenfified bypolymerase chain reaction(PCR) and reverse dot blot hybridization (RDB),including CD41-42(-TTCT)、IVS-Ⅱ-654(C﹥T)、-28(A﹥G)、CD71-72(+A)、CD17(AAG﹥TAG)、βE (GAG→AAG)、CD31(-C)、CD43(GAG﹥TAG)、-32(C﹥A)、-29(A﹥G)、-30(T﹥C)、CD14-15(+G)、CAP+40-43(-AAAC)、start codon Int(ATG﹥AGG)、CD27/28(+C)、IVS-Ⅰ-1(G﹥T)、IVS-Ⅰ-5(G﹥C). First, DNA samples were prepared by PCR amplification, hybridization,washing film. Then, color results were observed that blue hybridized spotsmeans positive.Results:1. The detection rate of β-thalassemia was63.16%(72cases) among114cases of β-thalassemia phenotype positive children.2.Therewere7different types of gene mutations in72cases of β-thalassemia, namelyCD41-42(-TTCT), IVS-Ⅱ-654(C> T), CD17(AAG> TAG),-28(A> G),CD71-72(+A), βE (GAG→AAG),-32(C> A). The most importantβ-thalassemia gene mutations were CD17, IVS-Ⅱ-654, CD41-42, accountingfor90.22%.3.15different genotypes were identified．52cases ofheterozygosity (72.22%),13cases of double heterozygote(18.05%),3cases oftriple heterozygotes (4.17%) and4cases of homozygote (5.56%) were dectcted.Heterozygous genotypes were: CD17(27.78%), CD41-42(19.44%), IVS-Ⅱ-654(22.22%) and-28(2.78%). Double heterozygous genotypes were: IVS-Ⅱ-654/CD17(8.33%), CD41-42/CD17(2.78%),-28/CD17(1.39%),CD41-42/CD71-72(1.39%), CD41-42/βE (1.39%), CD41-42/IVS-Ⅱ-654 (1.39%), CD41-42/-32(1.39%). Triple heterozygous genotypes were: IVS-Ⅱ-654+CD17/-32(2.78%), CD41-42+IVS-Ⅱ-654/-28(1.39%). Homozygousgenotype: CD41-42/CD41-42(2.78%) and IVS-Ⅱ-654/IVS-Ⅱ-654(2.78%).Conclusion:1.1.CD17（AAG﹥TAG）、IVS-Ⅱ-654（C﹥T）、CD41-42（-CTTT）are the mainly genotype of β-thalassemia in children of Luzhou.2.Heterozygous genotype are most common in genotype β-thalassemia of Luzhou.3. The detection rate of β-thalassemia is relatively high in children of Luzhou.It’s important to strengthen intervention of thalassemia,and to avoid the birth ofchildren with major thalassemia.4. RDB technique plays an important role inthe diagnosis of β-thalassemia, and it’s suitable for Chinese people to takegenetic testing in common types of β-thalassemia mutations.