LBX1 and attention deficit-hyperactivity disorder: The robust novelty-induced locomotor hyperactivity phenotype observed in both lbx1a(−/−) and lbx1b(−/−) animals suggests that dysregulated LBX1 function is associated with a risk for ADHD, as indicated by the perfect segregation of a SNP variant (rs941909) in an extended pedigree with a high density of affected individuals [28].