7873例产前诊断病例中有关嵌合体的临床分析

Retrospective analysis of the outcomes of chromosome mosaicism and clinical undertake in 7873 cses

目的探讨羊水检查中发现胎儿染色体嵌合体的临床分析。方法自2007年1月至2012年12月在北京大学人民医院产前诊断中心,对具有产前诊断指征的孕妇进行超声引导下羊膜腔穿刺抽取羊水,进行培养、制备染色体并分析其染色体核型。对羊水检测胎儿染色体嵌合的患者,建议再行脐静脉穿刺复查,结合超声检查结果进行综合分析和临床咨询,继续妊娠者新生儿出生后随访。结果羊水穿刺的7873份病例中,共发现染色体嵌合体92例,按照目前嵌合体类型定义,其中真性嵌合体19例(0.24%),假性嵌合体73例(0.93%)。19例羊水检查胎儿染色体嵌合的孕妇中,11例同意进一步行脐静脉血复查胎儿染色体,7例拒绝复查,1例胎死宫内。11例脐静脉血复查患者中,3例复查结果染色体核型正常(继续妊娠),8例脐血与羊水中核型一致(6例结合超声结果选择终止妊娠,1例继续妊娠,1例失访)。7例拒绝脐带血复查患者中,2例选择继续妊娠,5例结合超声结果终止妊娠。继续妊娠的6例患者,出生后随访的病例中目前未见异常。73例临床诊断为假嵌合的患者均选择继续妊娠,出生后随访,11例失访,另62例中1例为室间隔缺损,其余目前未见异常。结论羊水培养及染色体核型中出现假性嵌合体概率较高。在产前诊断中出现胎儿染色体嵌合者,应建议进一步抽取脐带血复查,并结合超声结果进行咨询,以防误诊。

Objective We estimated the frequency and clinical outcome of true mosaicism and pseudomosaicism in the prenatal diagnosis of cytogenetic disorders in 7873 eases pregnancies studied in our laboratory. Methods From January 2007 to December 2012, 7873 cases of high - risk pregnant women underwent invasive testing. Ultra- sound and clinical consult were offered and neonates were under folbw- up. Results Among the 7873 cases, 19 cases （0. 24 per cent） were diagnosed as true mosaics, 73 cases （0. 93 per cent） had pseudomosaicism involving less than two cells from the same culture with an identical abnormality. In 19 cases with true mosaics, 11 cases were obtained umbilical cord blood transabdominally again and the results of 8 cases were in accordance with that of amniocentesis samples （in those cases, 6 cases terminating pregnancy, one case continuing pregnancy and one case losing）, but the results of 3 cases were normality without mosaicism （the cases continuing pregnancy）. Other 7 eases refused to underwent umbilical cord blood （2 cases continuing pregnancy and 5 cases terminating pregnancy）. 73 cases of pseudomosaicism were seen in amniotic fluid specimens, and all these cases resulted in the live birth of normal healthy infants except for one fetus with ventricular septal defect and 11 cases lossing. Conclusions There was high pseudomosaicism in amniocentesis cultures. So, if necessary a third culture （including an in situ culture） is extensively analyzed for misdiagnosing as true mosaicism from pseudomosaicism. Detailed long term follow- up of prenatal diagnosed mosaics is also essential for assessing the clinical significance of the laboratory findings.