Adel Fahmideh M, et al. - The effect of parental age on the risk of phacomatoses in offspring was examined in this population-based nested case-control study. All individuals born and residing in Sweden between January 1960 and December 2010 were eligible for inclusion in this study. Using conditional logistic regression, data were analyzed. Researchers reported a consistent increase in the risk of de novo incidence of phacomatoses inclining to nervous system tumors in offspring with increasing paternal age, most pronounced for neurofibromatosis. On the other hand, maternal age did not appear to influence the risk. They observed an increased rate of new mutations in the NF1 and NF2 genes in spermatozoa of older fathers.