title: Monochorionic dizygous twins presenting with blood chimerism and discordant sex.
abstract: Monochorionic dizygous twins are probably more frequent than considered previously as many cases remain unrecognized, especially when the children have the same sex. Here we present a pair of dizygous, sex-discordant monochorionic twins who were conceived after artificial insemination. Histological examination of the placenta and extensive genetic studies of the healthy boy and girl clearly proved that they indeed were monochorionic dizygous twins with a fully joined blood circulation. We conclude that when counseling parents expecting monochorionic twins of discordant sex, not only a disorder of sexual differentiation in one of the twins should be addressed but also the possibility of dizygosity with a completely normal (sexual) development of both children.
authors.affiliation: Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. D.Smeets@gen.umcn.nl
authors.forename: Dominique
authors.initials: D
authors.lastname: Smeets
authors.forename: John M G
authors.initials: JM
authors.lastname: van Vugt
authors.forename: Ingrid
authors.initials: I
authors.lastname: Gomes
authors.forename: Simone
authors.initials: S
authors.lastname: van den Heuvel
authors.forename: Arno
authors.initials: A
authors.lastname: van Heijst
authors.forename: Annette
authors.initials: A
authors.lastname: Reuss
authors.forename: Hedi L
authors.initials: HL
authors.lastname: Claahsen-van der Grinten
mesh_terms: D000328:Adult; D046528:Chimerism; D002823:Chorion / Q000098:blood supply*; D005260:Female; D005307:Fertilization in Vitro; D047109:Fetal Development; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D010920:Placenta / Q000098:blood supply*; D011247:Pregnancy; D059285:Pregnancy, Twin; D012737:Sex Factors; D014429:Twins, Dizygotic / Q000235:genetics*; D016216:Ultrasonography, Prenatal