Rogers J G, Voullaire L, Gold H
Am J Med Genet. 1982 Feb;11(2):143-6. doi: 10.1002/ajmg.1320110204.
Monochorionic twins were phenotypically discordant for Down syndrome. Chromosome analysis of lymphocytes showed both to be mosaics. Fibroblast chromosome analysis showed that one twin was 46,XY and the other 47,XY, +21. Blood mosaicism appears to have resulted from placental anastomoses. The twins are presumed to be monozygotic on the basis of placentation, identical blood groups, HLA haplotypes, and serum proteins. We offer some speculation on the manner of occurrence of this rare event.
单绒毛膜双胎在唐氏综合征表型上不一致。淋巴细胞染色体分析显示二者均为嵌合体。成纤维细胞染色体分析表明，一个双胎为46,XY，另一个为47,XY, +21。血液嵌合体似乎是由胎盘吻合所致。基于胎盘形成、相同血型、HLA单倍型和血清蛋白，推测这对双胎为单合子。我们对这一罕见事件的发生方式进行了一些推测。
