This work proposes to explore an association between vitamin D status and ASD diagnosis and severity. In addition to its classical role of proper bone mineralization vitamin D, plays an important role in brain development, cognitive and behavioral function and the suppression of autoimmunity. Using the CHARGE study at the MIND Institute in California, Dr. Hammock will examine both levels of vitamin D as well as gene variants which control Vitamin D metabolism from mothers, newborn blood spots, children with autism and typically developing controls. They will also examine the relationship between vitamin D status and genetic influences which control vitamin D metabolism. The study will determine whether there is a difference in prenatal levels of vitamin D, and whether this contributes to later developing autism. Additional variables, such as diet and lifestyle habits will be examined to help explain this relationship. What this means for people with autism: Twenty years ago scientists advised mothers to keep their children out of the sun as much as possible. Although this led to a decrease in skin cancer, studies now show that approx. 25-57 % (depending on race and season) of adults are vitamin D deficient. Even if the differences are only social, the broad implications of vitamin D deficiency in bone health, immune modulation and cancer indicate that providing vitamin D status will be of value to the families of autistic children. Further, this information can be used as a basis for future treatment options.