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Relevance of Twin Data to Intrauterine Selection Special case of childhood cancer

Published online by Cambridge University Press:  01 August 2014

D. Hewitt  and
A. Stewart
D. Hewitt
Affiliation:
Dept. of Epidemiology and Biometrics, University of Toronto
A. Stewart
Affiliation:
Dept. of Social Medicine, University of Oxford

Extract

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The purpose of this paper is to draw attention to the statistical implications of abortion risks being greater for twins than singletons, greater for MZ than DZ twins, and greater for one member of a twin pregnancy than both members. This last fact is important, because if one twin aborts the other is usually mistaken for a singleton at birth; thus allowing a given number of nonconcordant abortions to have a marginally greater effect on twin frequency than double the number of concordant abortions.

This feature of abortion hazards is shown in Tab. I, which is based on Sandon's calculations of concordance effects. The figures show how much greater is the effect of a high rate of nonconcordant abortions (Case B) than the effect of an equally high rate of 90% concordant abortions (Case A) or a lower rate of 60% concordant abortions (Case C). In other words, a low frequency of twins in general (and MZ twins in particular) should be typical of an abortion-ridden population and might be a means of recognizing diseases whose prevalence rates are misleading, because they are associated with an abortion hazard (i.e., inherited diseases and diseases acquired during embryogenesis).

Type
Session 7 - Multiple Conception and Pregnancy
Information
Acta geneticae medicae et gemellologiae: twin research , Volume 19 , Issue 1-2 , April 1970 , pp. 83 - 86
Copyright
Copyright © The International Society for Twin Studies 1970

References

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