Approach to the Patient with Achondroplasia-New Considerations for Diagnosis, Management, and Treatment

Abstract

Achondroplasia is the most common disproportionate short-stature skeletal dysplasia. Features associated with achondroplasia are rhizomelia, macrocephaly, midface hypoplasia, and typical cognition. Potential medical complications include foramen magnum stenosis, hydrocephalus, middle ear dysfunction, obstructive and central sleep apnea, spinal stenosis, and genu varum. Recently, vosoritide, a C-type natriuretic peptide analogue, was approved by the Food and Drug Administration with the primary indication of increasing linear growth in all children with achondroplasia and open growth plates. Due to this, pediatric endocrinologists suddenly are encountering infants and children with achondroplasia in their clinic whose families are seeking treatment with vosoritide. There is an urgent need to provide practical guidance pertaining to the diagnosis, management, and surveillance of these patients. Specific to current clinical use of vosoritide and other growth-modulating therapies in development for patients with achondroplasia, it is important to recognize that 1. some children and their families do not automatically desire such treatment, 2. not all treated children exhibit a response in linear growth, and 3. treatment does not negate the necessity of actively surveilling for the potential complications of achondroplasia that are part of its natural history. The goal of this paper is to provide probable, contemporary clinical scenarios of infants and children with achondroplasia who may present to an endocrinologist. This information is especially crucial to the endocrinologist when there is no specialized skeletal dysplasia center near the family.

Keywords: CNP; achondroplasia; foramen magnum stenosis; skeletal dysplasia; vosoritide.

Figure 1.

Complications at different stages of life in patients with achondroplasia.

Figure 2.

Features for clinical suspicion of achondroplasia after birth. A, Deviation between the third and fourth digits (“trident hands”). B, Decreased interpedicular distance from upper to lower lumbar spine. C, Flat rounded iliac bones with narrow sacrosciatic notches, and radiolucency of the proximal femurs. Consent obtained from patient.