Topic: secondary microcephaly

RAC1 encodes a Rho family small GTPase that regulates actin cytoskeletal reorganization and intracellular signaling pathways. Variants in RAC1 can cause a phenotypically heterogeneous neurodevelopmental disorder with brain size anomalies and facial dysmorphism. Pathophysiological mechanism of this genetic disorder remains to be clarified. We investigated an early adolescent male with global developmental delay, intellectual disability, and secondary microcephaly. The novel de novo variant (NM_006908.5): c.92A>G, p.(E31G) in RAC1 was identified by whole exome sequencing. We then examined the