The FGD1 gene encodes a guanine nucleotide exchange factor (GEF) belonging to the DBL family of proteins. The FGD1 protein localizes preferentially to the trans-Golgi network of mammalian cells and activates Rho GTPase CDC42 by mediating the exchange of CDC42-bound GDP for GTP. FGD1 regulates secretory membrane trafficking and extracellular matrix remodeling, playing an important role in skeletal development and morphogenesis.
The protein is considered essential for normal embryogenesis in mammals. Mutations in the gene have been associated with Aarskog-Scott Syndrome (AAS), a condition characterized by facial, genital and skeletal anomalies.