User:SaswatPanda/Genetic Basis of the Osteochondrodysplasias

Osteochondrodysplasias are a heterogenous group of disorders characterized by abnormal growth and remodeling of cartilage and bone, affecting about 2 to 4.7 per 10,000 individuals. Osteochondrodysplasia is a general term for a disorder of the development (dysplasia) and cartilage("chondro").

Achondroplasia
Achondroplasia is a type of autosomal dominant genetic disorder that is a common cause of dwarfism. Achondroplastic dwarfs have short stature, with an average adult height of 131 cm (4 feet, 3.8 inches) for males and 123 cm (4 feet, 0.6 inches) for females.

The prevalence is approximately 1 in 25,000.

Genetic Basis
Mutations in the FGFR3 gene cause achondroplasia. The FGFR3 gene provides instructions for making proteins which maintain and evelop bone and brain tissues. Researchers believe that these mutations cause the FGFR3 protein is overly active in cases of achondroplasia, and this causes disturbances in bone and cartilage growth.

Presentation
Achondroplasia is a form of short-limbed dwarfism, it literally means "without cartilage formation."

Cleidocranial dysostosis
Cleidocranial dysostosis is a general skeletal condition named for the collarbone (cleido-) and cranium deformities which people with it often have. Common features include:
 * Partly or completely missing collarbones.
 * A soft spot or larger soft area in the top of the head where the fontanelle failed to close.
 * Bones and joints are underdeveloped.
 * The permanent teeth include supernumerary teeth.
 * Permanent teeth not erupting
 * Bossing (bulging) of the forehead.
 * Hypertelorism

Fibrous dysplasia
Fibrous dysplasia causes bone thinning and growths or lesions in one or more bones of the human body.

These lesions are tumor-like growths that consist of replacement of the medullary bone with fibrous tissue, causing the expansion and weakening of the areas of bone involved. Especially when involving the skull or facial bones, the lesions can cause externally visible deformities. The skull is often, but not necessarily, affected, and any other bone(s) can be involved.

Langer-Giedion syndrome
Langer-Giedion syndrome is a very rare genetic disorder caused by a deletion of chromosomal material. Diagnosis is usually made at birth or in early childhood.

The features associated with this condition include mild to moderate learning difficulties, short stature, unique facial features, small head and skeletal abnormalities including bony growths projecting from the surfaces of bones.

Mafucci syndrome
Maffucci syndrome is a sporadic disease characterized by the presence of multiple enchondromas associated with multiple simple or cavernous soft tissue hemangiomas. Also lymphangiomas may be apparent.

Patients are normal at birth and the syndrome manifests during childhood and puberty. The enchondromas affect the extremities and their distribution is asymmetrical.

Osteosclerosis
Osteosclerosis, an elevation in bone density, is normally detected on an X-ray as an area of whiteness, and is where the bone density has significantly increased. Localized osteosclerosis can be caused by injuries that compress the bone, by osteoarthritis, and osteoma.

Other

 * Deformity type Erlenmeyer flask gives a distal femur similar to an Erlenmeyer flask. It may result from Gaucher disease.
 * Kashin–Beck disease
 * Melnick–Needles syndrome
 * Ovine chondrodysplasia