FGFR1 and Pfeiffer syndrome: However, other mutated genes are important, mainly fibroblast growth factor receptor 1 FGFR1, known as basic fibroblast growth factor receptor 1, fms-related tyrosine kinase-2/Pfeiffer syndrome, and CD331, as a receptor of tyrosine kinase, whose ligands are specific members of the fibroblast growth factor family.