osteogenesis imperfecta, a genetic disorder involving defective development of the connective tissue. It is inherited as an autosomal-dominant trait and is characterized by abnormally brittle and fragile bones that are easily fractured by the slightest trauma. In its most severe form, the disease may be apparent at birth, when it is known as osteogenesis imperfecta type II. The newborn has multiple fractures that have occurred in utero and is usually severely deformed because of imperfect formation and mineralization of bone. Most infants die shortly after birth, although a few survive as deformed dwarfs with normal mental development if no head trauma has occurred. If the disease has a later onset, it is called osteogenesis imperfecta type I and usually runs a milder course. Symptoms generally appear when the child begins to walk, but they become less severe with age, and the tendency to fracture decreases and often disappears after puberty. Other manifestations of the condition include blue sclerae, translucent skin, hyperextensibility of ligaments, hypoplasia of the teeth, recurrent epistaxis, excess diaphoresis, mild hyperpyrexia, and a tendency to bruise easily and develop otosclerosis with hearing loss. There is a broad expressivity of the disease so that the number and extent of pathological features may range from minimal to severe involvement. Also called Adair-Dighton syndrome, brittle bones, fragilitas ossium, hypoplasia of the mesenchyme, osteopsathyrosis.
