title: [Sex ratio in Down syndrome. Estimation of chromosome 21 non-disjunction during spermatogenesis].
abstract: Derivation of a formula for determination of proportion of paternal trisomy 21 is presented. The formula can be applied for the literature data on sex ratio in the cases of paternal and maternal origin of the extra chromosome in the populations where direct studies of its origin can not be performed.
authors.forename: N V
authors.initials: NV
authors.lastname: Kovaleva
authors.forename: E V
authors.initials: EV
authors.lastname: Koval'chuk
mesh_terms: D002891:Chromosomes, Human, Pair 21 / Q000235:genetics*; D004314:Down Syndrome / Q000235:genetics*; D005220:Fathers; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D008540:Meiosis; D009630:Nondisjunction, Genetic; D010375:Pedigree; D012744:Sex Ratio; D013091:Spermatogenesis / Q000235:genetics*