Hypochondroplasia is a form of short-limbed dwarfism. This condition affects the conversion of cartilage into bone (a process called ossification), particularly in the long bones of the arms and legs. Hypochondroplasia is similar to achondroplasia, but the features tend to be milder. All people with hypochondroplasia are short. The adult height for men with this condition ranges from 138 to 165 cm (4 feet, 6 inches to 5 feet, 5 inches). The height range for adult women is 128 to 151 cm (4 feet, 2 inches to 4 feet, 11 inches). People with hypochondroplasia have disproportionately short arms and legs and broad, short hands and feet. Other clinical features may include an enlarged head (macrocephaly), limited range of motion at the elbows, and a sway of the lower back (lordosis). These signs are generally less pronounced than those seen with achondroplasia and may not be noticeable until early or mid-childhood. Mild to moderate mental retardation and learning disabilities have been reported in a small percentage of people with hypochondroplasia.