Osteogenesis imperfecta refers to a group of several genetic disorders that manifest in bone abnormalities. Persons suffering from this condition break their bones very easily usually after mild trauma or even in absence of any apparent cause. They frequently suffer from multiple fractures. Estimates indicate that 6 to 7 in every 100,000 people are affected. The distribution is almost uniform worldwide.
There are about eight types of the conditions which are designated type I to type VIII. There are mild differences in signs and symptoms that characterize the different types. Type is the mildest of them all while type II is the most severe; the rest are somewhere between these two. There is on-going research that seeks to identify the genetic factors that are responsible for these differences.
In the mild form such as type I, affected individuals start getting bone fractures early in childhood, adolescence and teenage. In most cases, there is predisposing minor trauma. As they grow older the incidence of fractures is significantly reduced. Accompanying features include hearing loss and a blue-grey tint on the sclera. Height is rarely affected.
The severe forms are associated with frequent bone fractures that typically start before birth without any predisposing factors. Other characteristics of the severe forms include blue sclerae, respiratory problems, abnormal teeth, hearing problems and a short stature. The respiratory problems are the result of extremely fragile ribs and underdeveloped lungs. Children may succumb shortly after birth due to respiratory distress.
Several studies have been carried out in an attempt to find the aetiological factors. The genes believed to carry the greatest responsibility in this disorder include CRTAP, COL1A1, COL1A2 and LEPRE1. Most cases of the conditions come about as a result of mutations that involve COL1A1 and COL1A2 genes. These are the genes that are responsible for the manufacture of collagen type 1 which is important in the integrity of connective tissues such as skin and bone.
The inheritance in this disorder is what is known as autosomal dominant pattern. This simply means that the disorder will manifest so long as one of the pairs of the copies of the gene pair involved in collagen synthesis is mutated. This is what is usually seen as regards collagen type I and IV. As for types II and III, there is no positive family history and the mutations are believed to be sporadic.
Currently there is no effective treatment for this disorder. The modes of management that are available aim at increasing bone strength and prevention of fractures. A drug known as alendronate has been tried in experimental cases but the results have been inconclusive. Conservative approaches include regular physical exercises, increased dietary calcium and vitamin D and prompt treatment of bone infections.
Other treatments that have been considered for management of osteogenesis imperfecta include physiotherapy, the use of physical aids and surgery. Physiotherapy is done to improve motility and to minimize fracture risks. The physical aids that can be used include wheelchairs, splints, crutches and grabbing arms. Surgical options include insertion of metallic rods in the long bones and spinal fusion to correct deformities such as scoliosis.
There are about eight types of the conditions which are designated type I to type VIII. There are mild differences in signs and symptoms that characterize the different types. Type is the mildest of them all while type II is the most severe; the rest are somewhere between these two. There is on-going research that seeks to identify the genetic factors that are responsible for these differences.
In the mild form such as type I, affected individuals start getting bone fractures early in childhood, adolescence and teenage. In most cases, there is predisposing minor trauma. As they grow older the incidence of fractures is significantly reduced. Accompanying features include hearing loss and a blue-grey tint on the sclera. Height is rarely affected.
The severe forms are associated with frequent bone fractures that typically start before birth without any predisposing factors. Other characteristics of the severe forms include blue sclerae, respiratory problems, abnormal teeth, hearing problems and a short stature. The respiratory problems are the result of extremely fragile ribs and underdeveloped lungs. Children may succumb shortly after birth due to respiratory distress.
Several studies have been carried out in an attempt to find the aetiological factors. The genes believed to carry the greatest responsibility in this disorder include CRTAP, COL1A1, COL1A2 and LEPRE1. Most cases of the conditions come about as a result of mutations that involve COL1A1 and COL1A2 genes. These are the genes that are responsible for the manufacture of collagen type 1 which is important in the integrity of connective tissues such as skin and bone.
The inheritance in this disorder is what is known as autosomal dominant pattern. This simply means that the disorder will manifest so long as one of the pairs of the copies of the gene pair involved in collagen synthesis is mutated. This is what is usually seen as regards collagen type I and IV. As for types II and III, there is no positive family history and the mutations are believed to be sporadic.
Currently there is no effective treatment for this disorder. The modes of management that are available aim at increasing bone strength and prevention of fractures. A drug known as alendronate has been tried in experimental cases but the results have been inconclusive. Conservative approaches include regular physical exercises, increased dietary calcium and vitamin D and prompt treatment of bone infections.
Other treatments that have been considered for management of osteogenesis imperfecta include physiotherapy, the use of physical aids and surgery. Physiotherapy is done to improve motility and to minimize fracture risks. The physical aids that can be used include wheelchairs, splints, crutches and grabbing arms. Surgical options include insertion of metallic rods in the long bones and spinal fusion to correct deformities such as scoliosis.
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