The purpose of this study is to learn more about how children with hypochondroplasia grow. Hypochondroplasia is a genetic condition that causes short stature and short limbs. Study procedures include a body check-up (measurements) and blood tests. Blood pressure, heart rate, and breathing rate will also be recorded. In addition, participants will be asked questions about how hypochondroplasia affects their daily life (physical activity, social relationships, emotions, etc.). If the parent/legal guardian agrees, leftover blood samples will be used for future research, including studies that examine the participant’s genes. The information may also be used to compare the participant’s growth without a study drug to their growth if they take part in a drug study.