Machin G, Still K, Lalani T
Department of Laboratory Medicine, University of Alberta Hospitals, Edmonton, Canada.
Am J Med Genet. 1996 Jan 22;61(3):229-36. doi: 10.1002/(SICI)1096-8628(19960122)61:3<229::AID-AJMG6>3.0.CO;2-P.
Monochorionic monozygotic twins frequently suffer complications from the presence of vascular anastomoses in their monochorionic placentas. Also, sharing of perfusion zones may be unequal, leading to marked growth discordance. This paper analyzes four measures of perinatal outcome (gestational age at delivery, perinatal mortality, birth weight discordance, and presence/absence of hydramnios) according to the vascular patterns of the monochorionic placentas. The worst clinical outcomes were associated with arteriovenous anastomoses in the absence of arterio-arterial and veno-venous anastomoses. The vascular patterns of monochorionic placentas cause significant fetal environmental differences within pairs of monochorionic monozygotic twins. These differences may cause life-long discordance for several phenotypic traits that are not genetically based, and which cause monochorionic monozygotic twins to be "non-identical."
单绒毛膜单卵双胞胎常常因单绒毛膜胎盘存在血管吻合而出现并发症。此外，灌注区的共享可能不均衡，导致显著的生长不一致。本文根据单绒毛膜胎盘的血管模式分析了围产期结局的四项指标（分娩时的孕周、围产期死亡率、出生体重差异以及羊水过多的有无）。最差的临床结局与缺乏动脉 - 动脉和静脉 - 静脉吻合的动静脉吻合有关。单绒毛膜胎盘的血管模式在单绒毛膜单卵双胞胎对之间造成了显著的胎儿环境差异。这些差异可能导致一些非基因决定的表型特征出现终生不一致，从而使单绒毛膜单卵双胞胎表现为“非完全相同”。
