GJA1 and oculodentodigital dysplasia: ODDD is primarily an autosomal dominant disorder caused by mutations in the gap junction protein alpha 1 (GJA1, OMIM#121014, HGNC ID: 4274, NM_000165.5) gene, which encodes the connexin 43 (Cx43) transmembrane protein (Paznekas et al., 2003).