caa a22 4500 388058838 CHVBK 20180307125114.0 cr unu---uuuuu 161130e19980801xx s 000 0 eng 10.1375/twin.1.4.212 doi S1369052300000453 pii (NATIONALLICENCE)cambridge-10.1375/twin.1.4.212 No paternal effect on monozygotic twinning in the Swedish Twin Registry [Elektronische Daten] Previous research has provided evidence for a genetic effect in monozygotic twinning, indicated by an increased risk for monozygotic women to have monozygotic offspring. However, since the biological mechanism for this trait is unknown, it is not clear if there exists a paternal inheritance. In this study we investigated twin pregnancies in offspring born in 1941-1996 to male twins in the Swedish Twin Registry and population controls born in 1926-1980. In total 4 225 331 offspring, of which 89 286 were twins, were studied. There was neither an increase in the probability for monozygotic men to have like-sexed twin offspring risk ratio (RR = 0.95; 95% CI = 0.77-1.13) nor an increase in the estimated number of monozygotic twin births. Thus, there is no evidence for a paternal effect on monozygotic twinning, suggesting that the gene(s) increasing the liability for division of the embryo are expressed in the mother and not in the fertilised egg. Copyright © Cambridge University Press 1998 monozygotic twins nationallicence multiple pregnancy nationallicence risk estimate nationallicence genetics nationallicence paternal inheritance nationallicence Lichtenstein Paul Institute for Environmental Medicine, Karolinska Institute, Stockholm. paul.lichtenstein@imm.ki.se Källén Bengt Tornblad Institute, University of Lund, Lund. Köster Max Epidemiological Center, National Board of Health, Stockholm, Sweden. Twin Research Cambridge University Press 1/4(1998-08-01), 212-215 1369-0523 1:4<212 1998 1 THG https://doi.org/10.1375/twin.1.4.212 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1375/twin.1.4.212 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Lichtenstein Paul Institute for Environmental Medicine, Karolinska Institute, Stockholm. paul.lichtenstein@imm.ki.se NATIONALLICENCE 700 1- Källén Bengt Tornblad Institute, University of Lund, Lund NATIONALLICENCE 700 1- Köster Max Epidemiological Center, National Board of Health, Stockholm, Sweden NATIONALLICENCE 773 0- Twin Research Cambridge University Press 1/4(1998-08-01), 212-215 1369-0523 1:4<212 1998 1 THG CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge