Introduction:Osteogenesis imperfect (OI) orbrittle bone disease is a rare clinically and genetically heterogeneoussystemic disorder of bone and connective tissue. Definition: It is a group of genetic diseases of collagen in which the bones are formed improperly, making them fragile and prone to breaking. (TheFreeDictionary.com, 2017)Type of OI: According to theOsteoporosis and Related Done Disease National Resource Center there are fourtype of OI following:Type I: The mildest and most common type _usually inherited.Type II: The most severe type _frequently life-threatening.Type III: Severe type_ usually no family history.Type IV: Moderate type_ often traced through family lines.
PathophysiologyPeople with OI are born with defective connective tissue (bone,ligament) or inability to make it because of deficiency of type-I collagen. Thisdeficiency arises from amino acids substitution of glycine to bulkier aminoacids in collagen triple helix structure which compromises interaction withother molecules. The body responds by hydrolysing the improper collagenstructure, however, if this does not happen then improper association betweencollagen fibre and hydroxyapatite crystals ensure resulting in brittle bones.Another theory explains the stress state of collagen fibrils at mutation sitesare altered leading to structural failure. These recent findings suggest thatthe disease is a multi-level phenomenon occurring at the genetic, macro, microand nano levels.CausesThere are manyreasons that causes Osteogensis imperfect. One of the most reasons is thedominant mutations happen on the gene (COL1A1 or COL1A2). Genetic (genes carryour hereditary and what make us look like our biological family) which do notwork properly.
In fact, people have two copies of most genes that are come fromtheir parent. If these gens do not work properly that mean there is not enoughcollagen in the body or the collagen do not work properly. This is lead to weakbones that break easily. Secondly, medical characteristics and issues such asbone deformity, short stature, and lower bone density. Finally, failure of theosteoclasts (a large multinucleate bone cell which absorbs bone tissue duringgrowth and healing to resorb none). RiskfactorBrittle bone disease is genetically inherited. In fact, there is a50% chance children will have OI if there parent has this disease.
Occasionallya child may be born with OI despite neither parent having the condition. Sign and symptom:As mention abovethere are many type of OI that mean this disease can range from mild to severe.In the mild OI the patient has following signs and symptoms: first, the bones breakeasily. This is because the density of bone is reducing due to luck of collagenwhich is response for produce protein. In fact, fracture of OI very highly fromperson to person even the patient have same type of OI or are in same family.
Second, reduce muscular strength or extra skeletal problem. Skeletal deformity is an importantcharacteristic of OI such as coxa vara (it is a deformity of the hip and it is not rare in OI specialityin severe form of this disease), whereby the angle between the head and theshaft of the femur is reduced to less than 120 degrees. In addition,there will be abnormal curvature of the spine (kyphosis and scoliosis). Infact, the degree and severity of scoliosis depend on aged of patient. In somecases the scoliosis associated with vertebra flatting and deformity of ribs whichall causes abnormality of pulmonary function.
Third, abnormality in healing ofwound and surgical incisions. Final, Obesity is a serious issue for somechildren and adults with OI. Lack of physical activity, small body size and adiet high in fat, salt and calories can quickly cause a person to be overweight.
However, in sever forms of the disease can cause hearing loss,heart failure, spinal cord problems and permanent deformities. It is importantto note that OI can sometimes be life-threatening if it occurs in babies eitherbefore or after short time of birth. Diagnosis· Doctor cannot always be diagnosed this disease at birth or during earlyinfancy because there are different types of OI and differing degrees ofseverity .The OI Foundation believes that genetic counselling should always bepart of the process when genetic testing for OI is done. The first step doctordo is collecting information about mutation because it helps them to know thecauses and identifying potential cures. In fact there are many tests which requireto identify OI such as collagen biochemical (skin biopsy), Collagen Molecular Testing (DNA analysis) and Testing for Recessive OIwhich give information about defects in the genes controllingCRTAP or P3H1.
Second X-Ray graphs which show abnormality in the bone. Forexample head, neck and spine X-Ray graphs show additional small bone kyphoscoliosis (is a deformity of the spinecharacterized by abnormal curvature of the vertebral column in two planes(coronal and sagittal). Also X-Ray graph in chest shows pigeon chest ( chestwall deformity in which the sternum protrudes inward). Finally MRI graph that can be used to assessextent of basilar invagination (it is infolding of the base of the skullthat occurs when the top of the C2 vertebra migrates upward). TreatmentThere is not yet anycare for OI. The only thing which doctor can do are preventing or controllingthe symptoms and develop bony mass and muscle strength. 1- Paediatric Treatment· Medication:IVbisphosphonates and zoledronate which use to increase bone mass.
In factsometime start in neonatal period if infant can breathe by own.· Physical and occupational therapy:Improve themobility of the joint and improve function, address joint, and improvecardiovascular status.· Surgery:Intramedullaryrodding surgery which use to support long bones. Also osteotomies which use tocorrect bowing of long bone. Other surgery like fixation use to stabilize thespine.2- Adulttreatment· Medication:Themedication of adult is similar to paediatric.
· Physical andoccupational therapy: The aim ofphysical therapy is to maintain mobility and adjust to physical changes due toinjury or aging.· Surgery:There aremany surgeries available such as joint replacement, fracture repair and rodrepair. PrognosisTheprognosis for a person with OI different depending on number and severity ofsymptoms. The most frequent causes of death for people with OI is respiratoryfailure.