title: Origin of acrocentric trisomies in spontaneous abortuses.
abstract: A total of 33 spontaneous abortuses with various acrocentric trisomies were studied for the origin of the extra chromosomes using Q- and R-band polymorphisms as markers. Eleven trisomic abortuses were informative: nine trisomic abortuses (one with trisomy 13, three with trisomy 21, and five with trisomy 22 including one with a 46,XX/47,XX,+22 mosaicism) originated at maternal first meiosis; a 21-trisomic abortus resulted from an error at maternal second meiosis (or first mitosis); and a 13-trisomic abortus was of maternal first or second meiotic origin. The abortus with mosaic trisomy 22 started as a 22-trisomic zygote resulting from an error at maternal first meiosis, followed by a mitotic (in vivo or in vitro) loss of the paternally derived chromosome 22.
mesh_terms: D000022:Abortion, Spontaneous / Q000235:genetics*; D002901:Chromosomes, Human, 13-15; D002904:Chromosomes, Human, 21-22 and Y; D005260:Female; D006801:Humans; D007621:Karyotyping; D008540:Meiosis; D008938:Mitosis; D009030:Mosaicism; D011247:Pregnancy; D014314:Trisomy