Case Report Osteogenesis Imperfecta Biology Essay

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A 24-year-old woman presented with low back pain after water-tubing. Her medical history included a Colles fracture at age 9 and several digital fractures in childhood. She denied smoking or consuming alcohol, she had adequate calcium intake, and her menstrual history was non-contributory. Her father, who had been diagnosed with osteoporosis, had had more than a dozen fractures, including a hip fracture at age 54. Her sister, age 35, also had osteoporosis.

On examination, the patient was 167 cm tall and weighed 52 kg. She had blue-gray sclera and normal dentition. A mid-peak ejection murmur was heard over the left sternal border. Musculoskeletal examination demonstrated scoliosis and paralumbar tenderness. Other systems were intact.

Lumbar radiographs confirmed an L1 compression fracture, and computed tomography demonstrated fracture stability without cord impingement. Osteoporosis was suspected, and dual-energy x-ray absorptiometry assessment of bone mineral density confirmed severe disease in the lumbar spine and femoral neck. Secondary causes of osteoporosis were ruled out. Owing to her physician's high index of suspicion, a diagnosis of OI was pursued. Because the patient presented as an adult with relatively minor symptoms, Type IA OI (the mildest form) was established. Systemic screening for disease complications included an echocardiogram, pulmonary function tests, an audiogram, and consultation with a geneticist. Therapy with calcium and vitamin D was initiated, and an in-depth discussion regarding bisphosphonates was pursued. Close follow up and screening of family members was arranged. [4]

Taken from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1479493/

Case Report: Osteogenesis imperfecta

Elusive cause of fractures

Elizabeth L. Strevel, MD, Alexandra Papaioannou, MD, MSC, Jonathan D. Adachi, MD, and Marty McNamara, MD

X-ray showing areas of fibula deformity (curvature) and tibia fracture of an OI patient

Taken from: http://www.szote.u-szeged.hu/radio/csont/csont4b.gif&imgrefurl

Etiology:

Osteogenesis Imperfecta (brittle bone disease) can be categorized as a dominant hereditary disorder in which there is a genetic defect in the production of type 1 collagen. Without genetic investigation, it is often incorrectly diagnosed as Osteoporosis, which is where a family history of the patient would come in handy. Osteogenesis Imperfecta can be distinguished from Osteoporosis by observing the age of the patient, as people over the age of 45 are more likely to have bone fractures due to Osteoporosis. Recurrent bone fractures are also more likely to be caused by Osteogenesis Imperfecta. Worldwide, OI in general affects approximately 7 out of 100,000 people, and is a significant contributing factor to injuries such as stress fractures of long bones. The main mutations are:

Collagen 1, alpha-1 polypeptide gene (COL1A1) located on chromosome 17

Collagen 1, alpha-2 polypeptide gene (COL1A2) located on chromosome 7

Mutation of the cartilage associated protein gene (CRTAP) required for prolyl 3-hydroxilation.

As a result, the body is unable to produce collagen, leading to poor formation of bones (particularly long bones) which explains the characteristic short stature of people with OI. Other symptoms of OI vary depending on the class that they are associated with, which are of 4 main types:

Type 1 - defect in the COL1A1 and COL1A2 genes, resulting in proper formation of collagen but synthesized in inadequate amounts. This form is mild and is the most common. Symptoms include blue sclera, loose connective tissue and joints and poor muscle tone. Affects 5 in every 100,000 people worldwide.

Type 2 - rare, defect in COL1A1, COL1A2 and CRTAP genes resulting in collagen that is both poorly synthesized and inadequate in amount. As a result, this form of OI is severe and lethal in infants between the20th to 28th week of pregnancy to about the 4th week after birth. Majority of infants born with Type 2 OI die within the first year of life due to malformation of rib cage and lungs resulting in respiratory failure. Patients also present with blue sclera, low birth weight and a soft skull. Affects 1 in every 100,000 people worldwide

Type 3 - rare, defect in COL1A1 and COL1A2. Substantial quantities of defective collagen are synthesized. This form is also severe and is characterized by multiple bone deformities that worsen overtime. Hearing loss, prenatal fractures and blue sclera are other symptoms seen in Type 3 OI. Worldwide, if affects approximately 2 in 100,000 people.

Type 4 - defect in COL1A1 and COL1A2. The amount of collagen synthesized is adequate but is synthesized poorly. The sclera of the eye in the type of OI is normal, possibility of early hearing loss, barrel-shaped rib cage, bone fracture before puberty and short stature. Bone malformations are mild to moderate. Affects 5 in every 100,000 people worldwide.

Blue sclera of the eye seen in OI patients.

Taken from: http://medlibes.com/uploads/blue-sclera-1.jpg&imgrefurl

Diagnosis:

Initially, X-rays, CT scans or Magnetic Resonance Imaging techniques can be used to identify types and areas of bone fractures. A family history of the patient will also help identify the cause of the symptoms of the disease. Prenatal diagnosis techniques like chronic villus sampling and ultrasound imagining can be used to detect the presence of bone malformation before birth. Also, discoloration of the sclera (blue-gray color) can be used to narrow the diagnosis of the disease. The use of gel electrophoresis is used to identify and confirm the type of genetic defect present.

Treatment/Therapy:

Increasing bone strength is the main method of treatment of Osteogenesis Imperfecta, as there is presently no known cure. Also, nitrogen bisphosphate drugs (inhibit the action of osteoclasts) such as alendronate, zoledronic acid and pamidronate are used to help increase bone mass and reduce the risk of fracture mainly in children (the nitrogen in the bisphosphates is utilized more in growing children than in adults). Physical therapeutic techniques such as light swimming are also done to help increase muscle tone of OI patients, as well as surgical intervention.

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