CYP27A1 and Dravet syndrome: The bone formation marker P1NP was decreased significantly in Ts65Dn mice compared to euploid mice at 24 months and in humans with DS at 19-51 years compared to control individuals, whereas the bone resorption marker TRAP 5b was decreased in Ts65Dn mice at 24 months; however, the bone resorption marker CTx was not significantly decreased in humans with DS aged 19-51 years (Fowler et al., 2012; McKelvey et al., 2013).