Supplementary Table
Case Type Criteria
Must meet ICD-10 criteria for autism and have clinical diagnosis of autism.
1
Must meet ADI-R and ADOS or ADOS-G criteria for autism.
IQ above 35.
Must have a history of language delay (no single words by 24 months or no phrase speech by 33 months).
Must meet ICD-10 criteria for Autism, Asperger's Syndrome, Atypical Autism or PDD.
Must meet ADI-R algorithm criteria on at least two domains can be 1 point below
2
3
4 threshold on the third one.
Must meet criteria for PDD on the ADOS-G.
IQ above 35.
Must have had abnormal development before 3 years of age although this does not have to have been autistic in quality.
Parents of case 1 cannot be included as a case 2.
Must meet ICD-10 criteria for Autism, Asperger's Syndrome or PDD-NOS.
Must meet ADI-R algorithm criteria on at least two domains can be 1 point below threshold on the third one.
Doesn't need to meet PDD cutoff on ADOS algorithm.
IQ above 35.
Must have had abnormal development before 3 years of age although this does not have to have been autistic in quality.
Must meet ICD-10 criteria for Autism, Asperger's Syndrome, Atypical Autism or PDD.
Must meet ADI-R algorithm criteria.
Must meet PDD cutoff on ADOS algorithm.
No IQ cutoff.
Must have had abnormal development before 3 years of age although this does not have to have been autistic in quality.
Criteria for all cases
Must have been diagnosed by the age 12 regardless of current age.
Age 4 years or greater.
Known medical aetiologies excluded.
Exclusion of clinically doubtful cases even when they meet ADI criteria.
1