Osteogenesis imperfecta is a disorder of bone that results from abnormalities in a group of genes that code for bone formation. The bones formed are weak and break very easily. Consequently, affected persons will frequently suffer multiple injuries following mild trauma or just spontaneously. It is estimated that close to 7 people are affected per 100,000 of population. The distribution is almost the same worldwide.
At least 8 types of the disorder have been profiled to date. These are type I through VII. The different types have many overlapping features and a few differences in terms of signs and symptoms. Type I is regarded as the least severe and type II is the most severe. The rest are somewhere in-between. Studies are going on to try and establish the reason as to why some people are affected by one type and not the other.
In type I and other mild forms, fractures are experienced early in childhood and adolescence. Fractures usually result from minor trauma. As these people grow older, the incidence of the same is markedly decreased. Other prominent features include a characteristic grey or blue tint on the white of the eye and varying degrees of hearing impairment.
Severe forms of the condition present with a high frequency of fractures. This typically starts way before the child is born. They suffer from numerous fractures that are not associated with any trauma. Additional features include hearing problems, abnormal teeth, blue sclera, short stature and respiratory problems. Respiratory problems are due to the presence of very fragile ribs as well as underdeveloped lungs.
A lot of studies have been carried out in this area. In terms of genetics the genes believed to be responsible for the abnormality include COL1A1, COL1A2, LEPRE1 and CRTAP. Mutations affecting the COL1A1 and COL1A2 alone are responsible for more than 90% of the cases. These genes code for proteins that are required for the synthesis of collagen type 1. This collagen is very important in the integrity of skin and bone as well as other connective tissues.
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.
There is no definitive treatment for this disorder at present. The available modes of management are aimed at strengthening the bones so as to reduce the incidence of fractures. The drug alendronate, a bisphosphonate, has undergone several clinical trials to check for its effectiveness but the results are still inconclusive. Other conservative measures include engagement in weight bearing exercises regularly and increasing the intake of calcium and vitamin D. Bone infections should be treated promptly.
There are other options that may be considered in managing osteogenesis imperfecta. These include physiotherapy, surgery and the use of physical aids. Physiotherapy involves the stretching of muscles and joints regularly by a trained professional in a bid to increase the strength and reduce the chances of getting fractures. Surgery is done to insert metal rods in some long bones and to correct spine defects. The physical aids that can be used include crutches, grabbing arms, splints and wheelchairs.
At least 8 types of the disorder have been profiled to date. These are type I through VII. The different types have many overlapping features and a few differences in terms of signs and symptoms. Type I is regarded as the least severe and type II is the most severe. The rest are somewhere in-between. Studies are going on to try and establish the reason as to why some people are affected by one type and not the other.
In type I and other mild forms, fractures are experienced early in childhood and adolescence. Fractures usually result from minor trauma. As these people grow older, the incidence of the same is markedly decreased. Other prominent features include a characteristic grey or blue tint on the white of the eye and varying degrees of hearing impairment.
Severe forms of the condition present with a high frequency of fractures. This typically starts way before the child is born. They suffer from numerous fractures that are not associated with any trauma. Additional features include hearing problems, abnormal teeth, blue sclera, short stature and respiratory problems. Respiratory problems are due to the presence of very fragile ribs as well as underdeveloped lungs.
A lot of studies have been carried out in this area. In terms of genetics the genes believed to be responsible for the abnormality include COL1A1, COL1A2, LEPRE1 and CRTAP. Mutations affecting the COL1A1 and COL1A2 alone are responsible for more than 90% of the cases. These genes code for proteins that are required for the synthesis of collagen type 1. This collagen is very important in the integrity of skin and bone as well as other connective tissues.
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.
There is no definitive treatment for this disorder at present. The available modes of management are aimed at strengthening the bones so as to reduce the incidence of fractures. The drug alendronate, a bisphosphonate, has undergone several clinical trials to check for its effectiveness but the results are still inconclusive. Other conservative measures include engagement in weight bearing exercises regularly and increasing the intake of calcium and vitamin D. Bone infections should be treated promptly.
There are other options that may be considered in managing osteogenesis imperfecta. These include physiotherapy, surgery and the use of physical aids. Physiotherapy involves the stretching of muscles and joints regularly by a trained professional in a bid to increase the strength and reduce the chances of getting fractures. Surgery is done to insert metal rods in some long bones and to correct spine defects. The physical aids that can be used include crutches, grabbing arms, splints and wheelchairs.
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