Orthopedic The main symptom of<unk>  is fragile, low mineral density bones; all types of<unk>  have some bone involvement. In moderate and especially severe<unk> , the long bones may be bowed, sometimes extremely so. The weakness of the bones causes them to fracture easily; a study in Pakistan found an average of 5.8 fractures per year in untreated children. Fractures typically occur much less after puberty, but begin to increase again in women after menopause and in men between the ages of 60 and 80. Joint hypermobility is also a common sign of<unk> , thought to be because the affected genes are the same as those that cause some types of Ehlers–Danlos syndrome. Otologic By the age of 50, about 50% of adults with<unk>  experience significant hearing loss, much earlier as compared to the general population. Hearing loss in<unk>  may or may not be associated with visible deformities of the ossicles and inner ear. Hearing loss frequently begins during the second, third, and fourth decades of life, and may be conductive, sensorineural, or a combination of both ("mixed"). If hearing loss does not occur by age 50, it is significantly less likely to occur in the years afterwards. Mixed hearing loss is most common among those with<unk>  of all age groups, while conductive hearing loss is most likely to affect older people, with sensorineural hearing loss most likely to affect children. Although relatively rare,<unk> -related hearing loss can also begin in childhood; in a study of forty-five children aged four to sixteen, two were found to be affected, aged 11 and 15. In a different 2008 study, the hearing of 41 people with<unk>  was checked. The results showed that 88% of those over 20 years of age had some form of hearing loss, while only 38% of those under 20 did. Hearing loss is most common in type I<unk> ; it is less common in types III and IV. Other parts of the inner ear may also be affected by<unk> . causing balance issues; however, only small studies have found links between vertigo and<unk> .<unk>  may worsen the outcome of medical treatments which correct hearing loss. Besides<unk> 's association with sensorineural hearing loss,<unk>  is associated with a number of neurological abnormalities, usually involving the central nervous system, due to deformities in the skeletal structures surrounding it. Neurological complications, especially basilar invagination, may adversely affect life expectancy. In<unk> , this is most often due to upwards migration of the dens, a feature of the C2 vertebra. Neurosurgery may be needed to correct severe abnormalities when they risk the patient's life or cause either great suffering or intolerable neurological deficits. Systemic As its biological causes have been more precisely determined, it has become more widely recognized that while the primary disease process of<unk>  happens in the bones, the most common types of<unk> —those caused by type I collagen gene mutations—affect virtually all of the human body's organs in some way. Type I collagen is present throughout the circulatory and respiratory systems: from the ventricles of the heart itself, to the heart valves, to the vasculature, it is an integral part of the connective tissue of the lungs. As such, cardiovascular complications, among them aortic insufficiency, aortic aneurysm, and arterial dissections, are sometimes comorbid with<unk> , but not as frequently as they are comorbid with Marfan syndrome. Respiratory illnesses are a major cause of death in<unk> . The most obvious source of respiratory problems in<unk>  is pulmonary insufficiency caused by problems in the architecture of the thoracic wall. However, respiratory tract infections, such as pneumonia, are also more fatal among those with<unk>  than the general population. Those with more severe ribcage deformities were found to have worse lung restriction in a small-scale 2012 study involving 22 Italian patients with<unk>  types III and IV, plus 26 non-affected controls.<unk> —especially its severe form type III—also has effects on the gastrointestinal system. It was found to be associated with recurrent abdominal pain and chronic constipation in two studies on patients affected by<unk> . Chronic constipation is especially common, and is thought to be aggravated by an asymmetric pelvis (acetabular protrusion). Especially in childhood,<unk> -associated constipation may cause a feeling of fullness and associated food refusal, leading to malnutrition.
Osteogenesis imperfecta
Lhermitte's sign
Dentinogenesis imperfecta
Cleidocranial dysostosis
Gerodermia osteodysplastica
Kyrle disease
Rhizomelic chondrodysplasia punctata
Acrodysostosis