What is Hypochondroplasia?

Hypochondroplasia is a condition that causes a person to develop short limbs as well as short hands and feet. A person with the condition is characterized by having a short physique. Typically, a male adult with the condition ranges in height from 4 feet 6 inches (about 1.37 m) to 5 feet 5 inches (about 1.65 m). A female adult with the disorder typically ranges from 4 feet 2 inches (about 1.27 m) to 4 feet 11 inches (about 1.5 m) in height. Generally, a person with hypochondroplasia is also noted for other traits, including an oversized head, partial range of movement at the elbows, and bowed legs.

One in 15,000 to 40,000 live births result in hypochondroplasia. The condition can be unnoticed at birth, as weight and length are often normal and the discrepancy in limb-to-trunk ratio is not pronounced. As a child becomes older, the condition becomes more evident – it typically is diagnosed between the ages of two and six.

Hypochondroplasia, a genetic disorder, is a form of dwarfism and is caused when there is a problem with cartilage forming into bones in certain areas of the body. The condition is the result of a mutation or alteration in the fibroblast growth factor receptor 3 (FGFR3) gene. No cure for the condition exists.

A person afflicted with hypochondroplasia often will have normal intelligence; but in 10 percent of cases, a child is born with mild mental retardation or grows to have learning disabilities. One who is living with the genetic defect is prone to neurological disorders, including sluggishness and abnormal reflexes due to pressure on the spinal canal. Also, a person with the condition is apt to suffer from other health problems, including sleep apnea and middle ear infections.

Hypochondroplasia can be treated through surgery. Surgical methods include lengthening the limbs by attaching rods to elongated bones in the legs and arms. After about 18 to 24 months, the tension on the rods increases the size of the body. This procedure, an elective surgery, can raise a person's height by a foot, but can also lead to infections and nerve problems.

A person with hypochondroplasia who has an offspring with a partner who does not have the genetic disorder has a 50-percent chance of bearing a child with the condition. While it is common for a person with hypochondroplasia to not suffer from learning disorders or mental retardation, the individual will have to deal with being short in size and may have trouble with activities such as driving. Support groups, including the Little People of America, Inc., exist to help individuals afflicted with the genetic condition. Such groups can offer personal support and provide information on medical issues, employment, and disability rights.