Association between idiopathic infantile macrocephaly and autism spectrum disorders.

We conducted a case-controlled, catch-up study of a cohort of boys born with macrocephaly in order to determine whether infantile macrocephaly is a risk marker for the later development of autism spectrum disorders. Our results show that infantile macrocephaly was associated with an increased risk of developing autism spectrum disorders (odds ratio 5.44, 95% CI 1.11-52.15; p=0.03). These findings suggest that neurobiological differences during infancy may predict behavioural manifestations of autism spectrum disorders.