Morssink L P, Sikkema-Raddatz B, Beekhuis J R, De Wolf B T, Mantingh A
Department of Obstetrics and Gynaecology, University Hospital Groningen, The Netherlands.
Prenat Diagn. 1996 Sep;16(9):845-51. doi: 10.1002/(SICI)1097-0223(199609)16:9<845::AID-PD958>3.0.CO;2-0.
In this patient-control study, we examined the impact of placental mosaicism on the concentrations of maternal serum human chorionic gonadotropin (MShCG) and maternal serum alpha-fetoprotein (MSAFP) in the second trimester of pregnancy. Patient and control groups were selected from 2347 women with a singleton pregnancy, who underwent chorionic villous sampling in the first trimester and from whom second-trimester serum samples had been collected. The concentrations of both serum markers, expressed in multiples of the median (MOM), in 35 women with confined placental mosaicism (CPM) were compared with those in 70 controls with uncomplicated pregnancies. Elevated MSAFP or MShCG was defined as a concentration of > or = 2.0 MOM. Of the 35 pregnancies with CPM, none had an elevated MSAFP level, as opposed to two out of the 70 women (2.9 per cent) in the control group (P = NS). Nine women in the placental mosaicism group (26 per cent) had an MShCG level of > or = 2.0 MOM, compared with five in the control group (7.1 per cent; P = 0.0135). Nineteen women in the placental mosaicism group (54 per cent) were screen-positive for Down's syndrome (cut-off 1:250), compared with 17 women (24 per cent) in the control group (P = 0.0042; relative risk = 2.3). The three highest MShCG levels were found in pregnancies with CPM that involved trisomy 16; all these women delivered a small-for-gestational age (SGA) infant. CPM, especially with trisomy 16, is associated with elevated levels of MShCG, but not with elevated levels of MSAFP. It is an important cause of false-positive results in serum screening programmes for fetal Down's syndrome. It is possible that abnormal MShCG levels in pregnancies with CPM result from dysfunctional placenta, caused by chromosomally abnormal areas. We therefore recommend increased surveillance of pregnancies with unexplained elevated MShCG levels.
在这项病例对照研究中，我们检测了胎盘嵌合体对妊娠中期母血清人绒毛膜促性腺激素（MShCG）和母血清甲胎蛋白（MSAFP）浓度的影响。病例组和对照组选自2347名单胎妊娠女性，她们在孕早期接受了绒毛取样，并采集了孕中期血清样本。将35例局限性胎盘嵌合体（CPM）女性的两种血清标志物浓度（以中位数倍数表示，MOM）与70例妊娠正常的对照者进行比较。MSAFP或MShCG升高定义为浓度≥2.0MOM。35例CPM妊娠中，无1例MSAFP水平升高，而对照组70例中有2例（2.9%）升高（P=无显著性差异）。胎盘嵌合体组9例女性（26%）MShCG水平≥2.0MOM，而对照组为5例（7.1%；P=0.0135）。胎盘嵌合体组19例女性（54%）唐氏综合征筛查呈阳性（截断值1:250），而对照组为17例（24%）（P=0.0042；相对危险度=2.3）。MShCG水平最高的3例出现在涉及16三体的CPM妊娠中；所有这些女性均分娩出小于胎龄儿（SGA）。CPM，尤其是伴有16三体时，与MShCG水平升高有关，但与MSAFP水平升高无关。它是胎儿唐氏综合征血清筛查计划中假阳性结果的重要原因。CPM妊娠中MShCG水平异常可能是由染色体异常区域导致的胎盘功能障碍引起的。因此，我们建议对MShCG水平不明原因升高的妊娠加强监测。
