福建人群香港型地中海贫血的基因变异检测

Variant analysis for patients from Fujian area with Hong Kong αα type thalassemia

目的分析福建省籍人群右向缺失型地中海贫血(-α^3.7)样本中香港型地中海贫血基因(Hong Kongαα,HKαα)检出率,探讨其临床意义。方法对10145份福建省籍人群地贫筛查阳性样本进行常规地贫基因诊断,应用单重PCR及巢式PCR技术对检测到的507例-α3.7/αα样本及2例电泳结果同时出现东南亚缺失型α-地中海贫血(--SEA)、-α^3.7及α2条带样本进行HKαα基因型检测。结果在507例-α3.7/αα样本中,共检出25例HKαα/αα,5例HKαα/-α^3.7,4例HKαα/αα合并CD41/42(HBB:c.126_129delCTTT)杂合变异,1例HKαα/αα合并IVS-Ⅱ-654(HBB:c.316_197C>T)杂合变异,另检出1例-α^3.7/anti4.2,2例电泳结果同时出现--SEA、-α^3.7及α2条带样本均为HKαα/--SEA,HKαα基因型在福建省籍人群中检出率为0.36%,在-α^3.7阳性样本中检出率为7.27%。结论在福建人群中检出一定比例的HKαα基因型,为临床提供更准确的地贫基因诊断结果及遗传咨询。

Objective To determine the frequency of Hong Kong αα(HKαα) gene in -α^3.7 positive samples among carriers from Fujian area. Methods Routine genetic testing for thalassemia was carried out for 10 145 patients with positive screening results. Single PCR and two-round nested PCR were utilized to detect HKαα among 507 patients with -α^3.7/αα and 2 patients for whom electrophoresis showed -α^3.7,--SEA and normal α2 alleles. Reverse dot blot test was used for detecting non-deletional α thalassemia and β thalassemia variants. Results Among the 507 patients with -α^3.7/αα, HKαα was identified in 35 cases, which included 25 HKαα/αα, 5 HKαα/-α^3.7, 4 HKαα/αα with heterozygous CD41/42 (HBB: c. 126_129delCTTT) variant, 1 HKαα/αα with IVS-Ⅱ-654 (HBB: c.316_197C>T) heterozygous variant. One patient was confirmed to have -α^3.7/anti4.2 genotype. The two cases with -α^3.7,--SEA and normal α2 alleles were confirmed to be HKαα/--SEA. The frequency of HKαα genotype in Fujian area was therefore 7.27% among patients with -α3.7 and 0.36% in the general population. Conclusion A certain proportion of HKαα has been detected in Fujian area, which will enable more accurate diagnosis and genetic counseling.