Abstract
As many as roughly 5% of men suffer from infertility; broadly defined as the inability to induce a pregnancy or the absence of offspring. Since mutations at a large number of genes (500 or more) can cause male infertility in Drosophila, it is possible that human male infertility is primarily caused by homozygosity for mutations at a fertility-related gene. In the present theoretical study, the effects of paternal exposure to 1 Gy of acute low LET radiation on infertility in the subsequent generation were estimated under the assumptions that (a) 100 to 4,000 genes are involved in human male fertility; (b) homozygosity for mutations at any one of these genes can cause infertility, and (c) the frequency of infertile males due to the homozygosity ranges from 1% to 20% in the population. The results indicate that, although the study endpoint is much more sensitive than that of monogenic hereditary disorders for the detection of mutagenic effects of radiation exposure, the predicted increase in the frequency of infertile men in the F1 generation would still be small. The maximum relative risk is estimated to be 1.013 under the conditions examined, and such a small increase would be undetectable. Overall, these results indicate that the detection of radiation effects in human germ cells would be an extremely difficult task, regardless of whether the investigators look at monogenic hereditary disorders or at diseases which involve multiple genes.
