Three M syndrome is an extremely rare genetic disorder characterized by low birth weight, short stature (dwarfism), characteristic abnormalities of the head and facial (craniofacial) area, distinctive skeletal malformations, and/or other physical abnormalities. The name "three M" refers to the last initials of three researchers (J.D. Miller, V.A. McKusick, P. Malvaux) who were among the first to identify the disorder. Characteristic craniofacial malformations typically include a long, narrow head (dolichocephaly), an unusually prominent forehead (frontal bossing), and a triangular-shaped face with a prominent, pointed chin, large ears, and/or abnormally flat cheeks. In addition, in some affected children, the teeth may be abnormally crowded together; as a result, the upper and lower teeth may not meet properly (malocclusion). Skeletal abnormalities associated with the disorder include unusually thin bones, particularly the shafts of the long bones of the arms and legs (diaphyses); abnormally long, thin bones of the spinal column (vertebrae); and/or distinctive malformations of the ribs and shoulder blades (scapulae). Affected individuals may also have additional abnormalities including permanent fixation of certain fingers in a bent position (clinodactyly), unusually short fifth fingers, and/or increased flexibility (hyperextensibility) of the joints. The range and severity of symptoms and physicial features may vary from case to case. Intelligence appears to be normal. Three M syndrome is thought to be inherited as an autosomal recessive genetic trait.