罕见β-珠蛋白基因突变导致儿童β-地中海贫血的研究

Study on rare β-globin gene mutations causing β-thalassemia in children

  • 摘要: 目的:研究儿童罕见β-地中海贫血(β-地贫)的β-珠蛋白基因突变类型、血液学特征和临床表现。方法:选取广西医科大学第一附属医院2022年1—12月检测地中海贫血的病例。血细胞分析仪行血常规检测,高效液相色谱法行血红蛋白(Hb)分析;跨越断裂点聚合酶链反应(Gap-PCR)法、荧光PCR 熔解曲线法和DNA 测序检测α-地中海贫血(α-地贫)和β-地贫基因突变。结果:共检出99例β-地贫患儿,其中2例为罕见β-珠蛋白基因突变导致β-地贫的患儿。病例1为1岁女患儿,轻度贫血,血常规示Hb 101.00 g/L,红细胞计数(RBC)5.43×1012/L,红细胞平均体积(MCV)56.90 fL,红细胞平均血红蛋白量(MCH)18.60 pg,红细胞平均血红蛋白浓度(MCHC)327.00 g/L,红细胞比容(HCT)0.31 L/L和红细胞体积分布宽度(RDW)0.19;Hb分析结果示Hb A25.70%,Hb F 2.60%。基因分析及DNA测序结果显示β-珠蛋白基因IVS-Ⅰ-2(T> C)突变杂合子。病例2为6岁男孩,轻度贫血,血常规示Hb 94.90 g/L,RBC 4.97×1012/L,MCV 59.97 fL,MCH 19.11 pg,MCHC 318.70 g/L,HCT 0.30 L/L,RDW 0.15;Hb分析结果示Hb A2 5.80%,Hb F 1.90%。基因分析及DNA测序结果显示β-珠蛋白基因CD95(+A)杂合子突变。结论:首次在国内发现β-珠蛋白基因CD95(+A)杂合子突变导致β-地贫的患儿,临床表现为轻度贫血,Hb A2水平增高;首次报道国内儿童β-珠蛋白基因IVS-Ⅰ-2(T> C)杂合子β-地贫的血液学特征、Hb分析和临床表现。这两种β-地贫基因突变类型在国内较罕见,提示临床上容易漏诊。

     

    Abstract: Objective:To study the mutation types, hematological characteristics and clinical features of the rare β-globin gene mutations causing β-thalassemia (β-thal) in children.Methods:Cases tested for thalassemia were selected in the First Affiliated Hospital of Guangxi Medical University from January 2022 to September 2022.Blood routine tests were performed by a blood cell analyzer.Hemoglobin (Hb) analysis was performed by high performance liquid chromatography.Gap polymerase chain reaction (Gap-PCR), fluorescent PCR melting curve and DNA sequencing were used to detect α-thalassemia(α-thal)and β-thal gene mutations.Results:A total of 99 cases of β-thal in children were detected.Among them, two cases were caused by rare β-globin gene mutations leading to β-thal.Case one was a 1-year-old girl with mild anemia, and her blood routine results showed Hb level 101.00 g/L, red blood cell count (RBC)5.43×1012/L, mean corpuscular volume(MCV) 56.90 fL, mean corpuscular hemoglobin (MCH) 18.60 pg, mean corpuscular hemoglobin concentration (MCHC)327.00 g/L, hematocrit (HCT) level 0.31 L/L and red blood cell distribution width (RDW) 0.19; Hb analysis showed that Hb A2 and Hb F were 5.70% and 2.60%, respectively.Gene analysis and DNA sequencing results showed that it was a β-globin gene IVS-Ⅰ-2(T> C) mutant heterozygote.Case two was a 6-year-old boy with mild anemia, and his blood routine results showed Hb level 94.90 g/L, RBC 4.97×1012/L, MCV 59.97 fL, MCH 19.11 pg, MCHC 318.70 g/L, HCT level 0.30 L/L and RDW 0.15; Hb analysis showed that Hb A2 was 5.80%and Hb F was 1.90%.Gene analysis and DNA sequencing results showed that it was a β-globin gene CD95(+A)heterozygous mutation.Conclusion:A heterozygous mutation of β-globin gene CD95(+A) is found to cause β-thal in pediatric patients for the first time in China, which is characterized by mild anemia and increased Hb A2.The hematological characteristics, Hb analysis and clinical phenotype of β-thal caused by the β-globin gene IVS-Ⅰ-2(T> C) mutant heterozygote are reported in the Chinese pediatric cases for the first time.These two types of βthal gene mutations are rare in China, indicating that they can be easily missed in clinical diagnosis.

     

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