Changes in an X chromosome gene called NONO have been shown to cause delayed development and intellectual disability in males.  In this article we describe three males with changes in NONO who have the delayed development and intellectual disability previously described but also have heart defects and/or abnormal heart muscles.  This suggest that changes in NONO may put males at risk for developing heart problems.   We also found that males with changes in NONO often have large heads and sometime have changes in the nerve fibers that connect the right and left sides of the brain. (By Dr. Daryl A. Scott, http://jmg.bmj.com/content/early/2016/08/22/jmedgenet-2016-104039 )