title: Case of non-mosaic trisomy 20 in amniotic fluid cultures without anomalies in the fetus: cytogenetic discrepancy between amniocytes and fetal blood.
abstract: We report a case of non-mosaic trisomy 20 detected prenatally by amniocentesis during the 16th week of pregnancy. Fetal blood sampling showed a normal karyotype and no fetal, neonatal or infant abnormalities were observed. Amniotic fluid cell karyotyping revealed a trisomy 20 (47,XY,+20) with 100% trisomic cells (38/38); however, a subsequent cordocentesis revealed a normal male karyotype. Moreover, a follow-up ultrasonographic examination did not reveal any major congenital malformations, and a healthy male infant was delivered subsequently at an appropriate gestational age without obvious anomalies. Cytogenetic analysis of blood lymphocytes from the infant revealed a normal karyotype, but cultured cells from the term placenta showed a mosaic karyotype 47,XY,+20/46,XY with 88% trisomic cells (44 of 50). Furthermore, no anomalies or developmental delays were observed in the neonatal period, thus suggesting two possibilities: confined placental mosaicism with the presence of normal and abnormal cell lineages, or generalized mosaicism affecting a limited number of tissues in both the placenta and fetus.
authors.affiliation: Shikoku Medical Center for Children and Adults, General Perinatal Medical Center, Zentsuji, Japan; Department of Obstetrics and Gynecology, Tokushima University Hospital, Tokushima, Japan.
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Maeda
authors.forename: Issei
authors.initials: I
authors.lastname: Imoto
authors.forename: Takashi
authors.initials: T
authors.lastname: Kaji
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Soichiro
authors.initials: S
authors.lastname: Nakayama
authors.forename: Minoru
authors.initials: M
authors.lastname: Irahara
mesh_terms: D000328:Adult; D000653:Amniotic Fluid / Q000166:cytology*; D002890:Chromosomes, Human, Pair 20; D020732:Cytogenetic Analysis; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011247:Pregnancy; D014314:Trisomy
keywords: amniocentesis; confined placental mosaicism; cordocentesis; non-mosaic trisomy 20; prenatal diagnosis