OSTEOGENESIS IMPERFECTA (TYPE III)
Osteogenesis imperfecta is a progressive autosomal dominant genetic disorder characterized by fragile bones, skeletal deformities, and weakened tendons. It is caused by the dominant mutation in a gene coding for type 1 collagen, important in forming ligament, teeth, and sclera. This is brought about by poor quality type 1 collagen in small quantities, resulting into most of the above effects (Prockop et al. 1994). Clinical manifestations include; weak bones that fractures, and are present at birth, from x-rays; healed fractures and short stature, blue sclera, triangular face, barrel-shaped rib cage, respiratory problems, scoliosis and bone deformity.
Mutations affecting the structure of the pro-alpha 1(1) and pro-alpha 2(1) chains of type 1collagen, lead to a substitution of an amino acid glycine residue in the triple helix structure. Amino acids possible of deletion are Serine, Cysteine, and Alanine. Side chains of larger amino acids however cause bulges in the collagen compounds, compromisingthe interaction between molecules and molecular Nano mechanics, and triggering hydrolyzation of the improper collagen by the body. Subsequently, the relationship between collagen fibrils and hydroxyapatite crystals, supposed to form the bone, is altered, causing brittleness (National Institute of Health, 2015).
Every clinician should take a comprehensive family history in addition to a full medical, surgical history, concerning the disorder. A focused physical exam in addition to testssuch as an x-ray as well as blood and bone marrow test, and a skin biopsy would help to determine the structure and quantity of type 1 collagen. A DNA test would confirm the diagnosis (Robby Novak). With these, no clinician need to call the police.Respiratory failure is, however, the most common cause of death, for the disorder has no cure. A patient may have the signs of an abused child, but a keen clinician can differentiate the two and save a parent from unnecessary and inappropriate emotional trauma and jurisdiction.
References
Beck K, Chan V. C, Shenoy N.K, Ramshaw J.A.M:Destabilization of osteogenesis imperfecta collagen It’s model peptides . Correlation with the identity of the residue replacing glycine. Pro.c.Natl.Acad.scie.USA.2000; 97;4273-4279
Ostogenesis Imperfecta Overview (Web Document). In National Institute of Arthritis and Musculoskeletal Disorders. 2015. By National Institute of Health. Accessed from;https://www.niams.nih.gov/Health_Info/Bone/Osteogenesis_Imperfecta/overview.asp
Roughley P J, Rauch F, Glorieux F.H:Osteogenesis Imperfecta -Clinical molecular diversity. EurCellMater. 2003;5:41-47
