Background
Acidic and basic fibroblast growth factors (FGFs) are members of a family of multifunctional polypeptide growth factors that stimulate proliferation of cells of mesenchymal, epithelial and neuroectodermal origin. Like other growth factors, FGFs act by binding and activating specific cell surface receptors. These receptors usually contain an extracellular ligand-binding region containing three immunoglobulin-like domains, a transmembrane domain and a cytoplasmic tyrosine kinase domain. Fibroblast growth factor-13 (FGF-13), also known as FHF-2, is involved in nervous system development. The FGF13 gene, mapping by linkage to the q26 region of the human X chromosome, is a candidate gene for the Borjeson-Forssman-Lehmann syndrome (BFLS), an Xlinked mental retardation. It is highly expressed in brain and skeletal muscle.