罕见和未知基因型珠蛋白生成障碍性贫血的分析与鉴定

目的对珠蛋白生成障碍性贫血(简称地贫)血液学表型阳性但未检出常见地贫基因型的疑似个体做进一步分子水平检测,以明确诊断。方法收集2015年5月至2018年8月在清远市妇幼保健院就诊的地贫血液学表型阳性但常见地贫基因型检测为阴性的标本96例(包括疑似α-地贫88例和β-地贫8例),分别采用单管多重PCR、DNA测序法、荧光定量PCR和芯片捕获测序法检测罕见和未知缺失型地贫基因。结果从上述疑似α-地贫标本中共检出罕见α-地贫基因型17例,其中泰国缺失型(--^THAI/αα)5例,菲律宾缺失型(--^FIL/αα)2例,α^ΔCD303例,α珠蛋白基因拷贝数增加(ααα^anti3.7或ααα^anti4.2)5例,并且发现2例新的α-地贫突变,即α^ΔCD272-279delAGCTTCGG和CD167-169insT。在8例β-地贫特征个体中检出罕见β-地贫基因型Poly A(A>G)2例,-90(C>T)3例,CD37(TGG>TAG)1例,IVS-I-2(T>A)1例,另外还鉴定出1例新的缺失型β-地贫基因(缺失位置为ch11:5,246,000-5,250,500,缺失长度为4kb左右)。结论对未检出常见地贫突变但血液学表型阳性个体进行深度分析,既可提高地贫基因的检出率,有利于遗传咨询和产前诊断,又可能发现新的地贫突变,丰富了中国人群的地贫基因突变谱。

Analysis and identification of rare and unknown genotype of thalassemia

Objective To investigate the rare or unknown genotypes of thalassemia for suspected as thalassemia subjects whose hematological phenotype were positive,but regular gene type were negative.Methods From May 2015 and August 2018,96 samples were collected from Qingyuan Municipal Maternity and Child Healthcare Hospital.In the patients,88 cases were suspected asα-thalassemia and 8 cases were suspected as β-thalassemia with positive hematological phenotype and negative regular gene type,which were selected to be detected for rare genotypes of thalassemia with Gap-PCR,DNA-sequencing,real-time PCR and unknown deletion genotypes of thalassemia by chip-captured-sequencing analysis.Results Seventeen cases with rare genotypes of α-thalassemia were detected,including Thailand deletion(--^THAI/αα,5 cases),Filipino deletion(--^FIL/αα,2 cases),α^ΔCD30(-GAG)(3 cases)and increasing of copies ofα-globin gene(ααα^anti3.7 or ααα^anti4.2,5 cases).Besides above mentioning rare mutation,two types of novel frame shift mutations(α^ΔCD272-279 delAGCTTCGG and CD167-169 insT)were detected.Among 8 samples suspected as β-thalassemia,2 cases were detected as Poly A(A>G),3 cases were detected as- 90(C>T),1 case were detected as CD37(TGG>TAG)and 1 case were detected as IVS-I-2(T>A).In addition,1 case of novel deletion mutation was identified by DNA sequencing and chip-captured-sequencing analysis the location was ch11:5,246,000-5,250,500,the deletion lenyth was about 4 kb.Conclusion Further analysis for rare and novel mutations of thalassemia can be explored for subjects with positive screening indicators and negative regular gene detection,so as to raise the detection rate of thalassemia gene,provide the help of genetic counseling and prenatal diagnosis,enrich gene mutation spectrum of thalassemia in Chinese population.