This work proposes to explore an association between vitamin D status and autism spectrum disorder (ASD) diagnosis and severity. Using the Childhood Autism Risks from Genetics and the Environment (CHARGE) study at the Medical Investigation of Neurodevelopmental Disorders (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.