title: Inverse maternal age effect in monosomy X.
abstract: The maternal age distribution of 45,X abortuses was significantly lower than that of chromosomally normal abortuses in two co-ordinated studies. One, carried out in Geneva, included 44 X-monosomic abortuses and the other, in Hiroshima, was based on 38 abortuses with a 45,X karyotype. It was deduced that 45,X conceptuses result from either non-disjunction during paternal meiosis or anaphase lag during meiosis or mitosis, and that anaphase lag is more frequent among young couples than among older ones.
mesh_terms: D000022:Abortion, Spontaneous; D000328:Adult; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007621:Karyotyping; D008423:Maternal Age; D011247:Pregnancy; D012729:Sex Chromosome Aberrations / Q000235:genetics*; D012730:Sex Chromosomes; D014960:X Chromosome