Pseudoachondroplasia

Pseudoachondroplasia is an inherited disorder of bone growth that produces mild to severe short stature. Growth is normal in early infancy, so the condition is usually first noticed at about two or three years of age, when a child falls behind peers in linear growth, develops a waddling gait or shows deformities of the lower limbs. It follows an autosomal dominant pattern and is caused by a heterozygous mutation in the COMP gene, which encodes cartilage oligomeric matrix protein; the same gene can also cause multiple epiphyseal dysplasia, a related but milder condition. It is also called PSACH or pseudoachondroplastic dysplasia. Despite the similar name it is clinically and genetically distinct from achondroplasia, and the two should not be confused.