Osteogenesis imperfecta is disorder of bone formation. It is caused by an abnormality in the genes that control synthesis of bone components. The affected persons will frequently suffer multiple fractures when subjected to mild trauma or even in the absence of the same. In terms of epidemiology, the prevalence has been estimated to stand at 6 to 7 persons per 100,000 of population. The distribution is more or less 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.
In the severe forms, the frequency of fractures is much higher. The problem starts even before the child is born. They suffer multiple fractures while still in the uterus usually without any predisposing trauma. There are other accompanying features that include abnormal teeth, blue sclerae, short stature and respiratory problems. The respiratory problems are caused by fragile ribs and the presence of underdeveloped lungs.
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 abnormal genes are inherited through an autosomal dominance pattern. What this means is that as long as one of the copies of genes that code for the collagen synthesis is mutated, the condition will manifest. This is what happens as regards the inheritance of types I and IV. Type II and three usually have no predisposing positive family history; they are just sporadic mutations.
There is no definitive treatment for this disorder at the present time. Several conservative approaches may be considered. These are aimed at increasing bone strength and reducing the incidence of fractures. A drug known as alendronate has been tried but results have not been satisfactory. It is recommended that affected individuals should engage on regular physical exercises and should also increase their dietary intake of calcium and vitamin D. Any bone infections should be treated as soon as possible.
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.
In the severe forms, the frequency of fractures is much higher. The problem starts even before the child is born. They suffer multiple fractures while still in the uterus usually without any predisposing trauma. There are other accompanying features that include abnormal teeth, blue sclerae, short stature and respiratory problems. The respiratory problems are caused by fragile ribs and the presence of underdeveloped lungs.
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 abnormal genes are inherited through an autosomal dominance pattern. What this means is that as long as one of the copies of genes that code for the collagen synthesis is mutated, the condition will manifest. This is what happens as regards the inheritance of types I and IV. Type II and three usually have no predisposing positive family history; they are just sporadic mutations.
There is no definitive treatment for this disorder at the present time. Several conservative approaches may be considered. These are aimed at increasing bone strength and reducing the incidence of fractures. A drug known as alendronate has been tried but results have not been satisfactory. It is recommended that affected individuals should engage on regular physical exercises and should also increase their dietary intake of calcium and vitamin D. Any bone infections should be treated as soon as possible.
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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