Aging, DNA damage, and reproductive outcome

Due to increasing life expectancy and a number of social factors, at least in the Western world, an increasing proportion of men who are considered to belong to an “older age group” have the wish of becoming fathers. One of the reasons is that many women postpone their first pregnancy, which automatically leads to higher age of the potential fathers. Furthermore, divorce and building new families has become more frequent, which also affects the paternal age. For those reasons, from a social and a medical point of view, the issue of age-dependent changes in reproductive capacity of the males is receiving increasing attention. Aging might not only lead to reduced fertility but also to an increase in the occurrence of sperm DNA defects, which potentially might be transmitted to the offspring. Understanding the mechanisms linking paternal age to reproductive outcome is, therefore, crucial not only for understanding this process, but first of all in order to prevent possible negative impact of male aging on fertility and health of the offspring. In this chapter we will focus on the available information regarding age and numerical or structural changes in the DNA. The issue of epigenetic effects will be covered in a separate chapter.