Management of prenatally detected trisomy 8 mosaicism.
We report on ten pregnancies with trisomy 8 mosaicism. Nine cases were prenatally detected in chorionic villi (n=6), amniotic fluid (AF) cells (n=2) or fetal blood (FB) lymphocytes (n=1). Follow-up laboratory investigations showed confined placental mosaicism (CPM) or pseudomosaicism in eight cases. In one case with ultrasound abnormalities, trisomy 8 mosaicism was detected in FB cells although cultured AF cells showed normal cells only. Another case of mosaic trisomy 8 was prenatally missed; cytogenetic analysis of short-term cultured villi revealed a normal male karyotype, while postnatally, trisomy 8 mosaicism was detected in peripheral blood lymphocytes and skin fibroblasts of the affected child. These findings indicate the difficulties in the prenatal diagnosis of trisomy 8 mosaicism. When found in chorionic villi, it mostly represented CPM, while in a case of true fetal trisomy 8 mosaicism, the cytotrophoblast cells showed a normal karyotype. So, the cytotrophoblast compartment of chorionic villi is a poor indicator of the presence or absence of fetal trisomy 8 mosaicism. Follow-up investigations including amniocentesis and especially fetal blood sampling are required to come to a definite prenatal diagnosis of trisomy 8 mosaicism.
van Haelst
M M
MM
Department of Clinical Genetics, Erasmus University Rotterdam, Rotterdam, The Netherlands. vanhaelst@kgen.azr.nl
Van Opstal
D
D
Lindhout
D
D
Los
F J
FJ
D000649:Amniocentesis; D000653:Amniotic Fluid / Q000166:cytology; D002478:Cells, Cultured; D015193:Chorionic Villi Sampling; D002898:Chromosomes, Human, Pair 8; D005260:Female; D005312:Fetal Blood / Q000166:cytology; D006801:Humans; D007621:Karyotyping; D008214:Lymphocytes / Q000648:ultrastructure; D009030:Mosaicism; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012189:Retrospective Studies; D014314:Trisomy