Thanatophoric Dysplasia: A severe form of neonatal dwarfism with very short limbs. All cases have died at birth or later in the neonatal period.Receptor, Fibroblast Growth Factor, Type 3: A fibroblast growth factor receptor that regulates CHONDROCYTE growth and CELL DIFFERENTIATION. Mutations in the gene for fibroblast growth factor receptor 3 have been associated with ACHONDROPLASIA; THANATOPHORIC DYSPLASIA and NEOPLASTIC CELL TRANSFORMATION.Achondroplasia: An autosomal dominant disorder that is the most frequent form of short-limb dwarfism. Affected individuals exhibit short stature caused by rhizomelic shortening of the limbs, characteristic facies with frontal bossing and mid-face hypoplasia, exaggerated lumbar lordosis, limitation of elbow extension, GENU VARUM, and trident hand. (Online Mendelian Inheritance in Man, http://www.ncbi.nlm.nih.gov/Omim, MIM#100800, April 20, 2001)Bone Diseases, DevelopmentalMacrocephaly: A congenital abnormality in which the occipitofrontal circumference is greater than two standard deviations above the mean for a given age. It is associated with HYDROCEPHALUS; SUBDURAL EFFUSION; ARACHNOID CYSTS; or is part of a genetic condition (e.g., ALEXANDER DISEASE; SOTOS SYNDROME).Osteochondrodysplasias: Abnormal development of cartilage and bone.Receptors, Fibroblast Growth Factor: Specific molecular sites or structures on cell membranes that react with FIBROBLAST GROWTH FACTORS (both the basic and acidic forms), their analogs, or their antagonists to elicit or to inhibit the specific response of the cell to these factors. These receptors frequently possess tyrosine kinase activity.Protein-Tyrosine Kinases: Protein kinases that catalyze the PHOSPHORYLATION of TYROSINE residues in proteins with ATP or other nucleotides as phosphate donors.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.