title: Blood chimerism in a dizygotic dichorionic pregnancy.
abstract: Blood chimerism in twins is known to occur through the transfer of hematopoietic stem cells between the fetuses via a common placenta. We present a case of blood chimerism in a dizygotic dichorionic twin pregnancy. The female twin was delivered at 34 weeks of gestation, and the male twin was stillborn. Pathologic examination confirmed dichorionic diamniotic placentas. The karyotype of the female child was obtained using peripheral blood sample, and it revealed a mixture of 46,XX and 46,XY cells (chi 46,XY[13]/46,XX[7]). FISH analysis performed on the buccal cells by using CEP X/Y probe (Abbott Molecular Inc., USA) revealed 100% XX signals (nuc ish Xcen(DXZ1x2)[500]). Gross examination of the external genitalia and abdominal ultrasonography revealed no definitive abnormal findings in relation to sex differentiation. When XX/XY chimerism is present in blood lymphocytes, careful examination of external genitalia and reproductive organs and further studies are required to detect chimerism in non-hematopoetic tissues. This is a rare case of blood chimerism in dichorionic placentas, in contrast to those in monochorionic placentas.
authors.affiliation: Department of Laboratory Medicine & Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. sunnyhk@skku.edu
authors.forename: Ja-Hyun
authors.initials: JH
authors.lastname: Jang
authors.forename: Haiyoung
authors.initials: H
authors.lastname: Jung
authors.forename: Jong-Hwa
authors.initials: JH
authors.lastname: Kim
authors.forename: Won-Soon
authors.initials: WS
authors.lastname: Park
authors.forename: Sun-Hee
authors.initials: SH
authors.lastname: Kim
mesh_terms: D000328:Adult; D001787:Blood Group Incompatibility / Q000000981:diagnostic imaging / Q000235:genetics*; D046528:Chimerism / Q000196:embryology*; D004200:Diseases in Twins / Q000000981:diagnostic imaging / Q000235:genetics*; D005260:Female; D005307:Fertilization in Vitro; D005865:Gestational Age; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007231:Infant, Newborn; D007621:Karyotyping; D008297:Male; D011247:Pregnancy; D014429:Twins, Dizygotic / Q000235:genetics*; D016216:Ultrasonography, Prenatal