46 Hypochondroplasia is a form dwarfism that affects the conversion of cartilage into bone, particularly in the long bones of the arms and legs. hypochondroplasia is similar to achondroplasia, but the features tend to be milder. people with this condtion usually have short arms and legs and broad, short hands and feet. other features include a large head, limited range of motion in the elbows, lordosis, and bowed legs. hypochondroplasia is caused by mutations in the fgfr3 gene and is inherited in an autosomal dominant fashion