Distribution of total mutation scores according to age of disease onset.

<p>The data are presented as the fitted Gaussian curve and the area under the curve. Distribution analysis, normality test, and data fit were performed with GraphPad Prism software. Early and late ages of disease onset are according to [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121511#pone.0121511.ref025" target="_blank">25</a>] and the references therein. Early age of onset is considered less than 6 years of age. Late age of onset is considered greater than 6 years (see text for more information).