Research has documented a strong male sex bias in attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and Tourette syndrome (TS). Among males, the hemizygous nature of chromosome X (Chr X) has been a known vulnerability factor. Still, the characterization of rare genetic variation in Chr X has not been conducted in large-scale studies. Addressing this gap in research, a recent Nature Communications study exploited informative recombinations seen in simplex ASD families to highlight the risk-prone regions on Chr X.