Osteogenesis imperfecta (OI), also known as brittle bone disease, is a group of genetic disorders that mainly affect the bones. It results in bones that break easily. The severity may be mild to severe. Other symptoms may include a blue tinge to the whites of the eye, short height, loose joints, hearing loss, breathing problems and problems with the teeth.
Osteogenesis imperfecta is a rare, inherited connective tissue disorder with substantial variation in clinical severity; milder forms of osteogenesis imperfecta (osteogenesis imperfecta type 1) may be underdiagnosed, because premature or severe postmenopausal osteoporosis can be the only manifestation.
People with mild forms of the condition typically have a blue or grey tint to the part of the eye that is usually white (the sclera), and may develop hearing loss in adulthood. Affected individuals are usually of normal or near normal height. Most of the mutations that cause osteogenesis imperfecta type 1 occur in the COL1A1 gene.
The characteristic blue sclera is caused by thinness and transparency of the collagen fibers of the sclera that allow visualization of the underlying uvea. The sclera may be thinned in congenital diseases such as osteogenesis imperfecta or in acquired diseases such as iron deficiency anemia.
Dr. Glenn Pomerance answered 46 years experience in Ophthalmology Uveal "show": Oi causes a thinning of the sclera, the white coat of the eye. It allows the blue-gray uveal layer beneath to be visible through the sclera.
Osteogenesis imperfecta (OI) is present at birth. It is often caused by a defect in the gene that produces type 1 collagen, an important building block of bone. There are many defects that can affect this gene. The severity of OI depends on the specific gene defect.
Blue sclerae, especially at infancy, is the most visible ocular sign in osteogenesis imperfecta but it is not always present. It is also often present in normal infants. In some patients, it is present early but disappears later in life. Some patients have significantly lower ocular rigidity, corneal diameters, and decreased globe length.
Type VII can also involve small head, blue sclera, bulging eyes; Some people with Type VIII have lived into their second or third decade; Type IX. ... Osteogenesis Imperfecta Foundation. (2008). Respiratory issues in osteogenesis imperfecta. Retrieved May 7, 2012, ...
Increasingly, genetic causes are used to define rarer forms of osteogenesis imperfecta. Type I (also known as classic non-deforming osteogenesis imperfecta with blue sclerae) is the mildest form of osteogenesis imperfecta. Type II (also known as perinatally lethal osteogenesis imperfecta) is the most severe.
A baby may have other outward signs of OI, such as blue-tinted sclera or loose joints, but these signs may go unnoticed in a family with no history or knowledge of OI. Furthermore, blue sclera can be seen even in infants without OI until about 18 months of age.