What is achondroplasia?
Achondroplasia is a type of rare genetic bone disorder. Achondroplasia is the most common type of these disorders. It causes the strong, flexible tissue called cartilage to not be made into bone as normal. This causes a series of signs, such as short arms and legs and a large head. This condition used to be called dwarfism. A boy with the condition will reach an average adult height of about 4 feet, 4 inches (52 inches). A girl with the condition will reach an average adult height of about 4 feet, 1 inch (49 inches). People with achondroplasia have normal intelligence and normal lifespan.
What causes achondroplasia?
Achondroplasia is a genetic disease. It is an autosomal dominant disease. This means that only one abnormal gene inherited from one parent leads to the condition. Most cases of achondroplasia are from a new gene mutation in families. This means the parents are average height and do not have the abnormal gene.
Which children are at risk for achondroplasia?
Having a parent with achondroplasia increases the risk of being born with the condition. But most babies born with the condition do not have a family history of it.
What are the signs of achondroplasia?
Signs can occur a bit differently in each child. They can include
- Large head size with large forehead
- Flattened bridge of nose
- Crowded or crooked teeth
- Short arms, legs, and fingers, but normal-sized torso
- Upper arms and thighs more shortened
- Bowed lower legs
- Curved lower spine (lordosis or sway-back), which may lead to hunchback (kyphosis)
- A small hump near the shoulders that usually goes away after a child begins walking
- Flat feet that are short and broad
- Extra space between the middle and ring fingers (trident hand)
- Poor muscle tone and loose joints
- Short spells of slow or stopped breathing (apnea)
- Middle ear infections that occur often, which may lead to hearing loss
- Delayed development milestones, such as walking occurring at 18 to 24 months instead of at 12 months
- Small canals in the spinal bones that can cause breathing problems
The signs of achondroplasia can be like other health conditions. Make sure your child sees his or her healthcare provider for a diagnosis.
How is achondroplasia diagnosed?
Achondroplasia can be diagnosed before birth by fetal ultrasound. This test uses sound waves and a computer to create images of the baby growing in the womb. DNA testing can also be done before birth to confirm fetal ultrasound results.
The condition can also be diagnosed after birth with a physical exam. You can track your child's growth for any signs of slowing. In particular, note if it's different from how your other children grew.
How we treat Achondroplasia
There is no treatment for changing the condition. But different kinds of treatment can be done to help relieve problems caused by the condition.
Surgery may be done to
- Treat hunchback (kyphosis)
- Lengthen the legs, in some cases
- Treat bowing of the legs
Other treatments may include
- Fixing dental problems. A child may need to be treated by an orthodontist. This is a dentist with special training in fixing the alignment of teeth.
- Treating ear infections right away. This is to avoid the risk of hearing loss.
- Tests to look for bone problems. The spine needs to be checked to prevent breathing problems. Breathing problems can happen if the upper end of the spine is compressed.
Other bones need to be checked to prevent leg pain or loss of function.
Treatment with growth hormone does not largely affect the height of a person with achondroplasia.