KDM2B and attention deficit-hyperactivity disorder: Chromosomal deletions encompassing the 12q24.31 region including KDM2B, as well as putative loss-of-function (pLOF) variants, missense variants and a small in-frame deletion, have been identified in individuals presenting with a variable expression of disease including developmental delay (DD)/intellectual disability (ID), autism, attention deficit hyperactivity disorder (ADHD), congenital organ anomalies and facial dysmorphism [2, 21–26].