Sex/Gender Differences in CARS2 and GARS-3 Item Scores: Evidence of Phenotypic Differences Between Males and Females with ASD.

Growing evidence suggests that autistic females are more likely to be diagnostically overlooked than males, perhaps due to differences in ASD presentations (van Wijngaarden-Cremers in JAMA 44:627-635, 2014). To investigate specific behaviours in which differences lie, we analysed profiles of 777 children using the Childhood Autism Rating Scale (Scholper in JAMA 29:489-493, 2010) or Gilliam Autism Rating Scale (Gilliam, 2014). Males demonstrated greater difficulty in six CARS2-ST items and seven behaviours on the GARS-3, mostly reflecting restricted and repetitive behaviours. Across all instruments, the only area in which females showed greater difficulty was fear or nervousness (CARS2-ST). No meaningful differences emerged from the CARS2-HF analysis. Where males showed greater difficulty, females were more likely to present with developmentally typical behaviour.