HKαα及其复合-α4.2缺失型α地中海贫血的临床分析

Clinical analysis of HKααand its combination with-α4.2 deletionα-thalassemia

目的:探讨香港型地中海贫血(HKαα)及其复合-α^(4.2)缺失型α地中海贫血(HKαα/-α^(4.2))的临床表型和血液学特征,为临床诊疗和遗传咨询提供参考。方法:收集2021年5月至2022年3月在广西医科大学第一附属医院进行地中海贫血检测的病例,采用血细胞分析仪进行血液学分析,高效液相色谱法(HPLC)进行血红蛋白分析;采用跨越断裂点聚合酶链反应(Gαp-PCR)和荧光PCR熔解曲线法(FCMA)进行α和β地中海贫血基因分析。结果:共检出165例患者,其中-α^(3.7)或-α^(4.2)缺失型α地中海贫血杂合子90例,--^(SEA)/-α^(3.7)或--^(SEA)/-α^(4.2)缺失型血红蛋白H(Hb H)病75例。在165例中检出1例罕见的HKαα/-α^(4.2)及5例HKαα。基因型为HKαα/-α^(4.2)的患者血常规检测结果:红细胞计数(RBC)5.59×10^(12)/L,血红蛋白(Hb)166 g/L,红细胞平均容积(MCV)88.60 fL,红细胞平均血红蛋白量(MCH)29.70 pg,红细胞平均血红蛋白浓度(MCHC)335.00 g/L;5例HKαα的患者血常规结果:RBC(4.77±0.26)×10^(12)/L,Hb(135.68±4.37)g/L,MCV(86.25±4.05)fL,MCH(28.47±1.12)pg,MCHC(330.48±3.75)g/L。6例患者中,Hb分析结果均未见异常,均无贫血表现,无黄疸及肝脾肿大。基因分析结果:6例患者ααα^(αnti4.2)基因检测结果均为阳性,1例基因型为HKαα/-α^(4.2),5例基因型为HKαα。结论:首次发现HKαα/-α^(4.2)患者无贫血症状,且血液学检测正常,提示此类病例在临床上较容易漏诊和误诊。

Objective:To explore the clinical phenotypic and hematological characteristics of Hong Kong allele(HKαα)and its combination with-α^(4.2) thalassemia(HKαα/-α^(4.2)),so as to provide reference for clinical diagnosis,treatment and genetic counseling.Methods:The cases of thalassemia detected in The First Affiliated Hospital of Guangxi Medical University from May 2021 to March 2022 were analyzed by hematology analyzer.The hemoglobin was analyzed by high performance liquid chromatography(HPLC),and the genes of α-thalassemia and β-thalassemia were analyzed by Gap Polymerase Chain Reaction(Gap-PCR)and Fluorescence PCR melting curve analysis(FCMA).Results:A total of 165 patients were detected,including 90 cases of-α^(3.7) and-α^(4.2) deletional athalassemia heterozygotes and 75 cases of--^(SEA)/-α^(3.7) or--^(SEA)/-α^(4.2) deletional hemoglobin H(Hb H)disease.Among the 165 cases,1 case of rare HKαα/-α^(4.2) and 5 cases of HKαα were detected.The results of routine blood test in patients with HKαα/-α^(4.2) were as follows:red blood cell count(RBC)was 5.59×10^(12)/L,Hb was 166 g/L,mean corpuscular volume(MCV)was 88.60 fL,mean corpuscular hemoglobin(MCH)was 29.70 pg,mean corpuscular hemoglobin concentration(MCHC)was 335.00 g/L.The blood routine results of 5 HKαα patients were as follows:RBC was(4.77±0.26)×10^(12)/L,Hb was(135.68±4.37)g/L,MCV was(86.25±4.05)fL,MCH was(28.47±1.12)pg,MCHC was(330.48±3.75)g/L.Among the 6 patients,Hb analysis showed no abnormality,no anemia,no jaundice and hepatosplenomegaly.The results of gene analysis showed that all the 6 patients were positive for ααα^(anti4.2),1 patient had the genotype of HKαα/-α^(4.2),and 5 patients had the genotype of HKαα.Conclusion:It is found for the first time that the patients with HKαα/-α^(4.2) have no symptoms of anemia,and the hematological tests are normal,suggesting that such cases are easy to be missed and misdiagnosed in clinic.