A placental diploid cell line is not essential for ongoing trisomy 13 or 18 pregnancies.
Viable trisomy 13 or 18 pregnancies may be supported by the presence of a diploid cell line, confined to the outer layer of the placenta (cytotrophoblast). To establish the presence of diploid cells we investigated five random biopsies from placentas of trisomy 13 (n = 8) and trisomy 18 cases (n = 6) of newborn infants and terminated pregnancies by means of fluorescence in situ hybridisation on interphase nuclei (n = 100). In 12 of these 14 placentas (including all five liveborns) 80% or more of the analysed nuclei showed three spots, suggestive of the presence of a full trisomy. In the other two placentas (both cases of trisomy 18) mosaicism was detected at most investigated sites. Thus, in contrast with earlier studies, these results show that a significant diploid cell line present in the placenta, confined to the trophoblast, is not a pre-requisite for intrauterine survival in the investigated cases.
Schuring-Blom
G H
GH
Department of Clinical Genetics, Academic Medical Center, Amsterdam, The Netherlands. G.H.Schuring@AMC.UVA.NL
Boer
K
K
Leschot
N J
NJ
D000328:Adult; D002460:Cell Line; D002882:Chromosomes, Human, Pair 13; D002887:Chromosomes, Human, Pair 18; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D007231:Infant, Newborn; D010920:Placenta / Q000473:pathology; D011247:Pregnancy; D014314:Trisomy / Q000235:genetics*