The majority of neuro-developmental disorders (NDDs) such as intellectual disability are likely due to alterations in the genome. It has been shown that about 30% of these patients have losses or gains of large segments of the genome containing many genes or whole chromosomes as in trisomy 21. In this study, we evaluated the contribution of small gains and losses sizing less than 500 kb affecting only few or single genes. We showed that such smaller changes cause NDDs in 2% of patients. In addition, we discovered three novel genetic conditions associated with losses of the genes MED13L, CTNND2 or ACOT7. Our findings are useful for better diagnosis and management of patients with NDDs. (By Prof. Anita Rauch, http://jmg.bmj.com/content/early/2014/08/08/jmedgenet-2014-102588 )