摘要目的 总结206例地中海贫血(简称地贫)产前诊断家系资料,分析其地域分布、基因型分布以及胎儿产前基因诊断结果,用于指导临床遗传咨询,避免高风险地区严重类型地贫患儿的出生. 方法 206例地贫产前诊断家系来自2008年1月至2009年12月期间于广州南方医科大学南方医院产前检查的地贫携带者孕妇及其配偶,抽取夫妇双方外周血和胎儿绒毛、羊水或脐血样本并提取DNA,以跨越断裂位点的聚合酶链反应(gap-polymerase chain reaction,gap-PCR)技术和反向点杂交技术(reverse dot blot,RDB)对a和β-地贫常见突变位点进行检测,同时对临床表型阳性而常见突变位点检测结果阴性的样本进行DNA测序.婴儿出生后半年电话随访婴儿表型. 结果 206例产前诊断家系来自包括黑龙江在内的12个不同省份和地区.a-地贫的基因突变类型有--SEA/、-a 3.7/、-a4.2/、αCSα/和αQSα/,全部为试剂盒中可检测的突变类型；而β-地贫的基因突变除常见的试剂盒中可检测到的类型外,还有中国型G γ+(Aγδβ)0、-28(A→C)、CD54-58 (-TATGGGCAACCCT)和CD37(G→A)等4种突变类型无法用常规试剂盒做出诊断.57例α-地贫家系中,产前诊断严重类型地贫11例(19.3％),包括巴氏水肿胎8例和Hb H病3例,杂合子26例(45.6％),正常胎儿20例(35.1％);149例β-地贫产前诊断家系中,严重类型地贫28例(18.8％),杂合子82例(55.0％),正常胎儿39例(26.2％),其中1例β-地贫杂合子合并13-三体.11例严重类型α-地贫胎儿、28例严重类型β-地贫胎儿和1例β-地贫杂合子伴13-三体胎儿均在围产期前后接受了终止妊娠的处理.结论　地贫的发病地域从长江以南各省逐渐扩散至一些北方地区.运用gap-PCR和PCR-RDB技术对地贫家系进行产前基因诊断,检出严重类型地贫胎儿,是降低高危地域严重类型地贫患儿出生的有效手段.但目前的试剂盒覆盖的检测位点在β-地贫筛查中存在漏诊现象,因此对临床表型阳性而常见突变位点检测结果阴性的样本进行DNA测序是十分必要的.此外,在进行地贫产前诊断的同时,也要注意染色体病产前诊断指征的确定.

abstractsObjective To summarize the geographical distribution,phenotype and genotype data of 206 thalassemia families underwent prenatal diagnosis to provide information for clinical genetic counseling and avoid the birth of severe thalassemia children. Methods Totally,206 thalassemia families were collected from Southern Medical University Nanfang Hospital from January 2008 to December 2009.Genomic DNA was extracted from peripheral blood,villus,amniotic fluid or cord blood from the couples or the fetuses.Gap-polymerase chain reaction (gap-PCR) and reverse dot blot (RDB) technology were used to detect the common α and β-thalassemia mutations.DNA sequencing was used to detect the rare mutations.Follow-up visit were done half a year after the fetuses were born. Results The 206 thalassemia families came from 12 provinces and areas across China,including Heilongjiang province.Mutations detected in α-thalassemia families included --SEA/,-α3.7/,-α4.2/,αCS α/ and αQS α/,which were all included in the testing kit. While there were 4 kinds of β-thalassemia mutations,Gγ+ (A γδβ)0,-28(A→C),CD54-58(-TATGGGCAACCCT) and CD37(G→A),could not be identified with routine testing kit. The 57 α-thalassemia families consisted of 11(19.3％) severe thalassemia,induding 8 Bart's hydrops syndrome and 3 Hb H disease,26(45.6％) heterozygote and 20(35.1％) normal infants,and the 149 β-thalassemia majors families consisted of 28 (18.8％) severe thalassemia,82(55.0％) heterozygote and 39 (26.2％) normal infants.Among the β-thalassemia heterozygotes,there was one 13-trisomy.Follow-up visit found that babies with Bart ' s hydrops syndrome (n =8),Hb H disease (n =3),β-thalassemia majors (n =28) and β thalassemia heterozygote combined with 13-trisomy(n=1) were aborted. Conclusions Thalassemia was found in some north area other than south of China,which should be paid more attention by clinicians.Gap-PCR and PCR-RDB technology are effective measures for thalassemia prenatal diagnosis in identifying major thalassemia fetuses before their birth,thus reduce the birth rate of thalassemia baby.But missed diagnosis might exist during the screening,so it is necessary to perform DNA sequencing on those patients with positive symptoms and negative common genetic diagnostic results.At the same time,prenatal diagnosis of chromosomal disorders should not be neglected for high-risk families.