The Children of Atomic Bomb Survivors A Genetic Study (1991) / Chapter Skim
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Atomic Bomb Exposure and the Pregnancies of Biologically Related Parents
Atomic Bomb Exposure and the Pregnancies of Biologically Related Parents
Pages 271-279
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From page 271... ...
Assessment of this risk in man has been hampered by a lack of basic information regarding such variables as spontaneous rates of mutation, selection pressure, average overdominance of nominally recessive mutant genes, and others. Furthermore, and fortunately so, the number of human populations exposed to high or moderately high amounts of ionizing radiations are few.
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From page 272... ...
In its simplest terms the main line of the argument is that the addition of radiation-induced mutants to the more homozygous' and presumably less elastic, genetic back',round of inbred children may produce a relatively greater effect than would be apparent if the same mutants were superimposed on the more heterozygous genetic background of noninbred children, that is, children born to unrelated parents. It seemed unwise, therefore, in the analysis of the data from Hiroshima and Nagasaki, to simply pool the present observations with those on noninbred children, particularly since the inbred children were not uniformly distributed over the various exposure classes to be described shortly.
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From page 273... ...
incomplete information on birth weight, birth rank, maternal age. Or parental exposure, (2 ~ relationship of uncertain degree' more remote than second cousins, or closer than first cous 1 623 THE CHILDREN OF ATOMIC BOMB SURVIVORS 273
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From page 274... ...
A less sensitive procedure is to pool the various types of parental relationship within each of the exposure cells, and then contrast the pooled observations. The validity of this latter approach rests on several assumptions, the most important of which is that the average coefficient of inbreeding, as well as the variances of these coefficients, is the same in each of the exposure cells.
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From page 275... ...
The sex ratio data on the offspring of tile related parents alone did not reveal a significant exposure effect. However, when taken in conjunction with the data presented on the unrelated parents, there emerged small, but consistent differences in the sex ratio compatible with the effects to be expected if sex-linked lethal genes were induced by the radiation.
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From page 276... ...
Nagasaki Mother's Exposure 1 2 3-5 1,481 25 0.(~169 204 0.0147 21 o 30 a 670 98 Total 2,249 33 0.01040.01020.0147 28623513 407 0.0140-0.0136 1364 0.07690.0156 N 1,7069861342,826 Total m 2811241 p 0.01640.01120.(~1490.0145 eflicients are both negative in sign although neither is significantly different from zero. The surprise with which one greets this failure to demonstrate significant differences among the exposure groups will be in part a function of 1 626 whether one views natural selection as primarily favoring homozygotes or heterozygotes.
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From page 277... ...
Table 4 presents the distribution, by There may, then, be no contradiction city of birth and parental exposure, of Table The Distribution by City of Birth and Parental Exposure of Infants Dying in the Perinatal Period Born to Parents Who Were Biologically Related a. Hiroshima Mother's Exposure 123-5 Total N1,1232891591,571 1 d4815467 p0.042?
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From page 278... ...
: "Analy sis of the frequency of malformed infants by city and parental exposure reveals no significant, consistent effect of parental exposure." '`Analysis of the stillbirth data fails to reveal significant differences be tween cities or consistent significant effects of parental exposure." Finally' "No con sistent, significant effect of parental expo sure on neonatal mortality emerges from the data obtained in Hiroshima and Nagasaki on deaths occurring in the first six days post partum." The present find inDs are not, then, at variance with those previously reported for pregnancy termi nations to unrelated parents. What now are the conclusions which we can draw from these data?
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From page 279... ...
This worI; was sponsored by the Atomic Bomb Casualty Commission, Field Agency of the National Academy of Seienees-National Research Council of the United States and the National Institute of Health of Japan. Analysis of these data was sponsored by the Atomic Energy Commission under a grant to the University of Michigan (Contract AT (11-1 )
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