What is the definition or description of: achondroplasia?

Abnormal bone growth: that is caused by a mutation affecting fibroblast growth factor and results in shortened bones. It is one of the major causes of dysproporotinate dwarfism. The mutation can be spontaneous, especially in advanced paternal age, or inherited as an autosomal dominant. It especially affects the proximal limb bones, prominent forehead, increased lordosis or kyphosis and either bowed or knock knees.