I've lived in California my whole life and had no idea this existed, so here is the information for others. The Regional Centers assist with all developmental disabilities.
http://www.dds.ca.gov/RC/RCList.cfm
You simply have to apply for services, and, if accepted, the evaluation will be free. If you are diagnosed, they are also able to provide other services. They also assist in cases where the fetus or infant is at risk for a DD.