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Race, Zygosity, and Mortality Among Twins: Interaction of Myth and Method

Published online by Cambridge University Press:  01 August 2014

C.E. Boklage
C.E. Boklage*
Affiliation:
Genetics Program, East Carolina University School of Medicine Greenville, North Carolina, USA
*
Genetics Program, East Carolina University School of Medicine Greenville, NC 27858-4534, USA

Abstract

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For epidemiological purposes, it is customary to assume that same-sex (SS) dizygotic (DZ) twin pairs are approximately equal in number to unlike-sex (OS)-DZs, the remainder of the SS pairs being monozygotic (MZ). It is also customary to consider OS-DZs to be epidemiologically representative of all DZs, which can only mean that difference in frequency of any trait between OS and SS twins is due to the MZ fraction of the SS twins. Since this is assumed as a premise, there is little value in its usual appearance as the result. The basic tenet of twin biology, that most twin excess anomalies are due to MZs, is a myth self-perpetuated by a methodological tautology, and is false, at least for mortality. In a consecutively ascertained and prospectively studied sample of 616 twin pairs, over 80% diagnosed for zygosity, it can be shown that the standard assumption mentioned above have given impossible answers. The most probable possible answer is that mortality does not differ greatly with zygosity overall, but that SSDZ mortality is much higher than that of OS twins, and probably even higher than that of MZs. Race differences in the probable answers further suggest that standard assumptions of the Weinberg method may have consistently provided false explanations for race differences in the OS fraction of twin pairs.

Keywords

Twin mortalityWeinberg methodZygosity
Type
Research Article
Information
Acta geneticae medicae et gemellologiae: twin research , Volume 36 , Issue 3 , July 1987 , pp. 275 - 288
Copyright
Copyright © The International Society for Twin Studies 1987

References

REFERENCES

1.Boklage, Ce (1981a): On the timing of monozygotic twinning events. Prog Clin Biol Res 69A: 155–165.Google Scholar
2.Boklage, CE (1981b): On the distribution of monrighthandedness among twins and their families. Acta Genet Med Gemellol 30:167–187.Google ScholarPubMed
3.Boklage, CE (1985): Interaction between opposite-sex dizygotic fetuses and the assumptions of Weinberg difference method epidemiology. Am J Hum Genet 37:591–605Google Scholar
4.Boklage, CE (1987): Developmental differences between twins and singletons in distributions of dental diameter asymmetries. Am J Phys Anthropol (in press).Google Scholar
5.Boklage, CE (1987): Twinning, nonrighthandedness, and fusion malformations: Evidence for heritable causai elements held in common. Am J Med Genet 28:67–84.CrossRefGoogle Scholar
6.Derom, C, Derom, R, Vlietinck, R, Van Den Berghe, H, Thiery, M (1987): Increased monozygotic twinning rate after ovulation induction. Lancet i:1236–1238.Google Scholar
7.Derom, C, Bakker, E, Vlietinck, R, Derom, R, Van den Berghe, H, Thiery, M, Pearson, P (1985): Zygosity determination in newborn twins using DNA variants. J Med Genet 22:279–282.Google Scholar
8.Derom, R, Thiery, M (1976) Intrauterine hypoxia - A phenomenon peculiar to the second twin. Acta Genet Med Gemellol 25:314–316.CrossRefGoogle Scholar
9.Elston, RC, Boklage, CE (1978): An examination of fundamental assumptions of the twin method. Prog Clin Biol Res 24A: 189–199.Google Scholar
10.Hill, AVS, Jeffreys, AJ (1985): Use of minisatellite DNA probes for determination of twin zygosity at birth. Lancet, Dec 21/28:1394–5Google Scholar
11.James, WH (1971): Excess of like-sexed pairs of diziygotic twins. Nature 232(5308):277–278.CrossRefGoogle ScholarPubMed
12.James, WH (1975): Sex ratio in twin births. Ann Hum Biol 2:365–378.CrossRefGoogle ScholarPubMed
13.James, WH (1976): The possibility of a flaw underlying Weinberg's Differential Rule. Ann Hum Genet 40:197–199.CrossRefGoogle ScholarPubMed
14.James, WH (1979): Is Weinberg's Differential Rule valid? Acta Genet Med Gemellol 28:69–71Google ScholarPubMed
15.Layde, PM, Erickson, JD, Falek, A, McCarthy, BJ (1980): Congenital malformations in twins. Am J Hum Genet 32:69–78.Google ScholarPubMed
16.Myrianthopoulos, NC (1970): An Epidemiological survey of twins in a large prospectively studied population. Am J Hum Genet 22:611–629.Google Scholar
17.Myrianthopoulos, NC (1985): Malformations in Children from One to Seven Years: A Report from the Collaborative Perinatal Project. New York: Alan R Liss.Google Scholar
18.Nylander, PPS, Corney, G (1969): Placentation and zygosity of twins in Ibadan, Nigeria. Ann Hum Genet 33:31–40.CrossRefGoogle ScholarPubMed
19.Uchida, IA, Freeman, VCP, Gedeon, M, Goldman, J (1983): Twinning rate in spontaneous abortions. Am J Hum Genet 35:987–993.Google Scholar
20.Vlietinck, RF (1986): Determination of the zygosity of twins. Thesis, Katholieke Universiteit, Leuven.Google Scholar