Palmer N, et al. - The high-confidence sex-specific recurrence rates of autism spectrum disorder (ASD) among siblings were estimated in this trial. The yielded data affirmed the existence of higher rates of ASD among males than among females in the general cohort. More specific guidance was obtained with regard to the screening and counselling of families. This, in turn, could assist in informing prospective analyses into the environmental and genetic factors which conferred the risk of ASD.