Novel alternative splicing of human faciogenital dysplasia 1 gene

The human faciogenital dysplasia 1 (FGD1) gene product plays an important role in morphogenesis. Its dysfunction causes Aarskog-Scott syndrome (MIM musical sharp 305400). To characterize the FGD1, we investigated its expression by RT-PCR and Southern blot analysis in normal tissues. We found novel alternative forms of the FGD1. One has a novel exon located in intron 8, named exon 8B (8B FDG1) and the other has an exon in intron 7, exon 7B (7B FGD1). The 8B FDG1 is expressed strongly in the brain, testis, spinal cord, trachea and stomach, and weakly in the thymus and lymphocytes. However, expression of the 7B FGD1 is weak and restricted in the testis and salivary gland. Insertion of each novel exon results in production of a premature termination codon, respectively, and the predicted proteins generated from them have only a proline-rich domain and an incomplete DH domain which potentially compete with the wild type of FGD1.