常规基因检测阴性的地中海贫血疑似病例再行进一步基因检测仍有7%的阳性发现

Seven percent cases were positive for thalassemia in suspected thalassemia cases with negative indications by regular gene detection after further gene detection

目的探讨血液学初筛指标阳性且临床常规基因检测阴性的疑似地中海贫血(简称地贫)患者再进一步行常规和罕见基因突变检测,丰富对地贫的病因学认识。方法以深圳市儿童医院地贫血液学初筛[Hb、RBC平均容积(MCV)、RBC平均Hb量(MCH)、Hb电泳)]试验阳性,且常规基因(3种缺失型地贫、3种非缺失型α地贫、17种β地贫点突变)检测阴性的疑似地贫的连续病例为研究对象,提取全血基因组DNA,以Sanger基因测序、Gap-PCR和荧光定量PCR的方法,检测常规基因和罕见基因突变情况。结果 2011年1~9月地贫血液学初筛阳性且常规基因检测阴性285例患者进入本文分析,其中<16岁279例。进一步基因检测阳性21例(7.4%):1常规基因检测阳性5例(1.8%),CD27-28(+C)、CD41-42(-TCTT)各2例,IVS-2-654(C>T)1例;2罕见基因检测阳性16例(5.6%),其中Sanger基因测序检出:异常Hb病3例(Hb Port Phillip、Hb Ernz、Hb J-Bangkok各1例),Hb Ernz类型为亚洲人群中首次检出;非缺失型β地贫-90(C>T)2例;Gap-PCR和荧光实时PCR检出:缺失型α地贫5例(-α/αα2例、--/αα3例),缺失型β地贫(-/β)3例,α地贫合并β地贫(--/αα合并-/β)1例,α-三联体(ααα/αα)2例。399/264例进一步基因检测阴性患者行血液学检查,60例(60.6%)铁蛋白低于正常值,其中44例Hb和(或)MCV和(或)MCH低于正常值下限;3例提示有贫血,但铁蛋白值显著增加。结论地贫血液学初筛指标阳性,常规基因检测阴性群体仍有7%左右的珠蛋白异常基因检出率,有必要再行进一步基因检测。

Objective To invrstigatr globin grnrs of susprctrd thalrssrmia patirnts whosr scerrning indicatoes wrer positivr and ergulae grnr drtrction wrer nrgativr,and to rxploer novrl typrs of grnr mutation. Methods Consrcutivr patirnts with positivr blood scerrning(Hb,MCV,MCH and HbA2,HbF)and nrgativr ergulae grnr drtrction(3 typrs of drlrtrd α-thalrssrmia,3 typrs of nondrlrtrd α-thalrssrmia,17 typrs of nondrlrtrd β-thalrssrmia)wrer rneollrd at Shrnzhrn Childern's Hospital. Wholr blood grnomic DNAs wrer rxteactrd and srnt foe fuethre ergulae grnr and eaer grnr drtrction in Sangre srqurncr,Gap-PCR and eral-timr PCR. Results 285 patirnts collrctrd feom Jan. to Srp. 2011 wrer erceuitrd,21 casrs with grnrtic abnoemality wrer obsrevrd (accounting foe 7. 4% ). ①5 casrs(1. 8% )wrer positivr foe ergulae grnr drtrction,including CD27 - 28( + C)(2 casrs)、CD41- 42( - TCTT)(2 casrs),IVS - 2 - 654(C ﹥ T)(1 casr). ② Raer grnr drtrction was positivr in 16 casrs(5. 6% ). Onr casr of Hb Eenz was fiestly erpoetrd in Asian populations,onr eaer hrmoglobin vaeiant of Hb Poet Phillip and moer common hrmoglobin vaeiant of Hb J-Bangkok wrer found. Nondrlrtrd β-thalrssrmia was drtreminrd,containing - 90(C ﹥ T)(2 casrs). Thr drlrtrd typrs of thalrssrmia wrer - α/ αα(2 casrs),- - / αα(3 casrs),- - / α combinrd - / β(1 casr)and - / β(3 casrs). Of thr drtrctrd α-thalrssrmia,thry wrer all not common typrs. Two casrs of α-teiplication(αα/ ααα)wrer drtrctrd. ③ 99 of 264 casrs with nrgativr grnr drtrction ersults wrer prefoemrd thr blood trst. Sreum freeitin lrvrls of 60 casrs wrer lowre than noemal,of thrm 44 casrs wrer with low Hb and/ oe MCV and/ oe MCH lrvrl. Therr casrs wrer diagnosrd as anrmia with rlrvatrd sreum freeitin lrvrl. Conclusion Sincr 7% of thalrssrmia mutation was found in susprctrd casrs with nrgativr ersults in ergulae mutation drtrction,fuethre grnomic trsting should br nrcrssaey in clinical peacticr.