罕见β-珠蛋白基因Codon 24(GGT>GGA)突变导致β-地中海贫血1例及文献分析

Rare β-globin gene Codon 24(GGT>GGA) mutation causing β-thalassemia:a case report and literature analysis

目的:分析罕见β-珠蛋白基因突变类型、血液学及临床特征。方法:收集疑为β-地中海贫血的病例120例。对病例进行全血细胞分类及计数、血红蛋白(Hb)电泳分析检测。用跨越断裂点PCR方法、荧光PCR熔解曲线方法、DNA测序等分析α-和β-珠蛋白基因突变类型。结果:120例β-地中海贫血病例中,检出1例为罕见β-珠蛋白基因突变,基因分析为Codon 24(GGT>GGA,HBB:c.75T>A)杂合子。该病例为男性,39岁,血常规检测显示:Hb 127.3 g/L,血红细胞(RBC)5.81×10^(12)/L,红细胞平均体积(MCV)70.29 fL,红细胞平均血红蛋白量(MCH)21.94 pg,红细胞平均血红蛋白浓度(MCHC)312.10 g/L。Hb分析显示Hb A_(2)4.5%,Hb F 0.4%。a-地中海贫血基因分析未发现常见的基因突变类型。结论:首次在国内发现罕见β-珠蛋白基因Codon 24(GGT>GGA,HBB:c.75T>A)突变导致β-地中海贫血。该病例在临床上易漏诊,应引起重视。

Objective:To study the mutation types,hematological characteristics and clinical manifestations of rare β-globin gene.Methods:A total of 120 suspected cases of β-thalassemia were collected.The whole blood cells were classified and counted,and hemoglobin (Hb) was analyzed by electrophoresis for all the cases.The mutation types of α-and β-globin genes were analyzed by cross break point PCR,fluorescence PCR melting curve analysis and DNA sequencing.Results:A total of 120 cases of β-thalassemia were detected,of which 1 case was a rare mutation of β-globin gene,and the genotype was Codon 24 (GGT>GGA,HBB:c.75T>A) heterozygote The case was a 39-year-old male,and the routine blood test showed the following results:Hb 127.3 g/L,red blood cell (RBC) 5.81x10^(12)/L,mean corpuscular volume (MCV) 70.29 fL,mean corpuscular haemoglobin(MCH) 21.94 pg and mean corpuscular hemoglobin concentration (MCHC) 312.10 g/L.Hb analysis showed tha Hb A_(2)was 4.5%and Hb F was 0.4%.The a-thalassemia genetic analysis did not identify common types of mutations.Conclusion:The rare β-globin gene Codon 24 (GGT>GGA,HBB:c.75T>A) mutation causing β-thalassemia is found in China for the first time.This type of case is clinically prone to misdiagnosis and should be given more attention.