DDX23 and Global developmental delay: DDX23 belongs to the DExD/H-box RNA helicase genes that have been associated with multi-organ diseases, neurodevelopmental disorders, brain malformations and several types of cancer.18,27,28  DDX23 (OMIM #612172) has recently been reported to be associated with a novel syndromic neurodevelopmental disorder.29 The phenotype includes developmental delay, muscle tone abnormalities and dysmorphic features.