Achondroplasia is a congenital skeletal dysplasia that is the most common cause of dwarfism.
Achondroplasia is caused by a gain-of-function mutation in fibroblast growth factor receptor 3 (FGFR3). Constitutive activity of FGFR3 impairs chondrocyte (cartilage) proliferation and differentiation, resulting in shortened extremities and macrocephaly (enlarged head relative to body). In particular, while long bones rely on endochondral ossification (cartilage-dependent), bones of the skull use membranous ossification (not reliant on cartilage) and are thus unaffected.
Find Achondroplasia and other Autosomal Dominant Diseases among Pixorize's visual mnemonics for the USMLE Step 1 and NBME Shelf Exams.