The advent of the new and high-throughput technologies such as next generation sequencing are contributing to better elucidate the implication of the rare variants on the ADHD susceptibility: interestingly it has been observed an increased burden of rare variants inside the 7R allele of DRD4 both in ADHD children72, and in adults75 that needed further investigation. Here, DRD4 is linked to attention deficit-hyperactivity disorder.