Health Supervision for Children With Achondroplasia

Abstract

This set of guidelines is designed to assist the pediatrician in caring for children with achondroplasia confirmed by radiographs and physical features. Although pediatricians usually first see children with achondroplasia during infancy, occasionally they are called on to advise the pregnant woman who has been informed of the prenatal diagnosis of achondroplasia or asked to examine the newborn to help establish the diagnosis. Therefore, these guidelines offer advice for these situations as well. Achondroplasia is the most common form of disproportionate short stature.1 The diagnosis is based on very specific features on the radiographs, which include a contracted base of the skull, a square shape to the pelvis with a small sacrosciatic notch, short pedicles of the vertebrae, rhizomelic (proximal) shortening of the long bones, trident hands, a normal length trunk, proximal femoral radiolucency, and, by mid-childhood, a characteristic chevron shape of the distal femoral epiphysis. Hypochondroplasia and thanatophoric dysplasia are part of the differential diagnosis, but achondroplasia can be distinguished from these because the changes in hypochondroplasia are milder and the changes in thanatophoric dysplasia are much more severe and invariably lethal. Achondroplasia is an autosomal dominant disorder, but approximately 75% of cases represent new dominant mutations. The gene for achondroplasia has recently been found. Achondroplasia is due to a change in the genetic information for fibroblast growth factor receptor 3.2,3 Almost all of the mutations have been found to occur in exactly the same spot. Now that the gene has been found and the mutation known, potential therapies and diagnostic methodologies are likely to be developed.