[Daltonism and the genetics of aging]

In order to test whether mutations giving rise to color vision deficiencies are more frequently inherited from older fathers, an exhaustive screening of births in the Namur region has allowed to isolate a sample of 225 descending sons of maternal grandfathers who were older than 45 years at their daughter's birth. The incidence of color vision defects was compared between this set of cases and three control groups totalling 959 boys from independent families. While these comparisons were not conclusive, we propose new hypotheses concerning the population dynamics of color vision deficiencies. Neomutations in X-linked pigment genes may be a marker of the overall genetic load borne by the X chromosome. Selection against such loaded X chromosomes may occur in the second generation, either in the course of embryogenesis, or during female gametogenesis. The future assessment of these novel hypotheses relies on the arbitration of molecular genetics.