According to the most recent statistics from the Centers for Disease Control, nearly 1 in 45 children born today in the United States have or will eventually have autism. Its symptoms and severity differ among individuals with the same diagnosis, yet all affected by the disorder have impaired social communication and social interaction skills, and restricted, repetitive patterns of behavior and/or interests.

One of the major roadblocks to understanding the causes of, and finding effective treatments for, autism is that it has diverse patterns of symptoms and associated disorders. Some individuals have seizures, but others do not. Some have troubling gastrointestinal problems, but others have none. Some have severe developmental delays, but others have normal or even enhanced IQs. This heterogeneity raises the possibility that there are several types of autism, with a variety of causes. This complexity limits both scientific progress and the development of effective treatments. Thus far, research on autism has not produced precise definitions of autism subtypes based on biomedical and behavioral characteristics.

The Autism Phenome Project or "APP" is the largest and most comprehensive longitudinal assessment of children with autism ever attempted. It aims to define clinically meaningful subgroups or phenotypes of autism based on distinct patterns of behavior and biological characteristics.


  • Boys between the ages of 2 to 3-1/2 at the time of the first visit
  • Have a diagnosis of autism spectrum disorder or are typically developing
  • Live with at least one biological parent
  • Must understand English

What does participation involve?

The APP is a longitudinal study with families returning for follow-up evaluations for several years. During the first year, participation involves 2 half-day visits to the UC Davis MIND Institute for behavioral assessments, a medical examination, and a blood draw. You will return for an evening visit to complete the MRI scan at the Imaging Research Center; this is done while your child is sleeping. For those families who live farther away from the MIND Institute, all activities may be scheduled in one 2-day visit, with hotel accommodations provided. We try to schedule the visits at your convenience, given the availability of staff and resources. The testing or procedures during each visit follow a general pattern, but the sequence may vary in order to accommodate your family’s needs.

One year later, your child will be asked to return for a repeat MRI scan. Two years after your first visit, your child will be asked to repeat some of the behavioral tests and repeat the MRI scan. When your child reaches 9-12 years of age, we will ask you to return for a repeat MRI scan and additional behavioral/medical evaluations.

What will you receive for participating in the study?

  • A comprehensive letter of information about your child’s performance on the behavioral assessments.
  • A copy of the MRI brain scan
  • A copy of the MRI report will be provided to your child’s physician, with your consent
  • Compensation for participating in each visit and mileage reimbursement

How can I find out more information?

Please contact our Research Study Coordinator, Katelyn Huynh, at 916-703-0404. She will be happy to answer any additional questions you may have.


New APP Detailed Overview »