TABLE 1

Descriptive Statistics on the Samples of US and Dutch Families of the ASD Probands

VariableUSDutch
Total number of people genotyped472528
    Male, %62.361.7
    Female, %37.738.3
Ethnic background, %a
    White95100
    Ethnic minority50
No. of probands per family
    1129183
    2210
    320
Average age of the probands, y10.979.85
Proband clinical diagnosesb
    Autism8488
    Asperger syndrome4612
    CDD70
    PDD-NOS3457
  • CDD indicates childhood disintegrative disorder; PDD-NOS, pervasive developmental disorder not otherwise specified.

  • a The analyses for the US sample were carried out with and without families of minority ethnic backgrounds. Because the results were virtually identical, we present here the results for the ethnically admixed sample.

  • b Clinical diagnoses were obtained by consensus among practicing clinicians at both sites, respectively, on the basis of the opinions of ≥2 independent evaluators.