Achondroplasia

What does the name mean?

Achondroplasia literally means failure or lack of cartilage formation. This is not strictly true as cartilage formation does occur in the growth plates of patients with achondroplasia.

How common is achondroplasia?

Achondroplasia is the most common skeletal dysplasia. Although the exact incidence is not known estimates range from 1 in 15,000 to 1 in 26,000 births (1,2).

Is achondroplasia inherited?

Achondroplasia is inherited in an autosomal dominant manner, but about 75% of patients with achondroplasia represent new mutations. These new mutations are typically arise from the father during sperm formation. Paternal age greater than 35 years has been found to be a risk factor (3,4).

What causes achondroplasia?

Achondroplasia is caused by a mutation in the fibroblast growth factor receptor-3 (FGFR-3) gene (3). Mutations which change the amino acid glycine to arginine at position 380 of the FGFR-3 protein account for >97% of all reported cases of achondroplasia. Normally the FGFR-3 protein functions as "brake" for endochondral bone growth. This typical G380R mutation actually increases the ability of the FGFR-3 protein to slow bone growth and causes the features of achondroplasia. This type of change associated with an increased ability is termed a "gain-of-function" mutation (4).

• What are the physical characteristics of Achondroplasia?
• How is the diagnosis made?
• What are the associated medical problems?
• Problems in the musculoskeletal system
• Problems elsewhere in the body
• What are things to watch out for?
• References