Rationale: Autism Spectrum Disorder (ASD) is defined by deficits in social interaction and communication identified before the age of 3 years. Modified Checklist for Autism in Toddlers (M-CHAT) is a sensitive tool for ASD screening in children 16-23 months. A limited number of studies with a small number of patients have documented the developmental profile of children with ASD during infancy. Retrospective evaluations of videotaped behavior of children with ASD at 8 months and at 12 months identified early signs of ASD. A few studies found early signs of ASD during infancy in siblings of autistic children. Data documenting the age of onset and regression in ASD is controversial and limited. No large prospective studies documented the specific developmental profile of children with ASD starting at 6 months of age. Defining a specific autistic pattern on a developmental screening test could help identify infants at risk for ASD and improve their outcome through earlier diagnosis and treatment. More recently, genetic tests have been shown to aid in early identification of ASD which facilitates earlier intervention. Genetic testing among siblings of children with autism can aid in identification of autism or other related disorders in the siblings.

PURPOSE: The purpose of this study is to learn about the early signs of autism in siblings of children with autism spectrum disorders.

• The investigators will enroll siblings of children with ASD. Those siblings who completed the Red Flags for Communication scale (RFC) at 6 months and/or at 12 months and failed the RFC at 12 months will be given a genetic screening test.
• It is the investigators goal to define a specific autistic pattern on a developmental screening test that could help identify sibling infants at risk for ASD and improve their outcome through earlier diagnosis and treatment and to evaluate if the results of the clinical screening test will correlate with the results of the genetic screening test.

Inclusion Criteria:

• The subject must be a sibling of a child with a previous expert clinical diagnosis of Autism Spectrum Disorder.

• Subjects will be included for the genetic test if he/she meets the following criteria:

  • At 12 months of age he/she failed two or more items on the RFC with at least one failed critical item
  • They have no significant known hearing, vision or motor impairment that will impact on their ability to perform on developmental assessments

Exclusion Criteria:

• Those children who do not meet the inclusion criteria
• Those who do not speak English will be excluded from this study.

Biological siblings of children with a previous expert clinical diagnosis of Autism Spectrum Disorder.