Skin fibroblasts from patients show a reduction of type I procollagen synthesis. Most cases are new mutations, but some are autosomal recessive occurring in 1 in 60,000 live births. The skull is soft and the limbs are short. The skin is fragile as well. The sclerae may be blue at birth and become less blue with age.
Inheritance is autosomal recessive with clinical variability in severity.
Very few patients reach adulthood. Children sustain multiple fractures and progressive kyphoscoliosis. The skull is soft and deformed. Most patients succumb to cardiorespiratory complications in infancy or childhood. Type IV osteogenesis imperfecta is characterized by osteoporosis leading to bone fragility of variable severity.