Achondroplasia

Achondroplasia is the condition that results in people growing to a short height, with an average height of those with achondroplasia at 4 foot 4 for males and 4 foot 1 for females. It also leads to disproportionately short limbs, and is an inherited genetic condition.

The reason that those with achondroplasia are so short is due to the fact that their cartridge does not properly form into bone, particularly in longer bones in the body. It is one of the oldest known birth defects and the most common cause of short stature.

The condition is usually noted at birth where there is a small hump which goes away with walking. There is often usually a prominent forehead, and many joints are able to extend more than normal (excluding the elbow joint). Achondroplastic children will also follow a different development schedule of motor skills than the average child.

What is done for those with achondroplasia?

Many of those with achondroplasia will lead normal lives with due guidance and attention from parents and doctors. This will include careful measurements of growth and head circumference. At times intervention may be required in the case of special problems. For example surgery may be required to decompress the spinal cord.

Any disproportion between the brain and the base of the skull can result in ‘water on the brain’ (hydrocephalus) which much be detected and treated promptly. There has also been experimental treatment with a human growth hormone to increase the growth rate.

Regarding pregnancy the larger head of the baby will increase the risk of vaginal bleeding which will be taken into account when planning birth and pregnant women with achondroplasia should have babies delivered by cesarean. The achondroplasia gene is not inherited by all babies of achondroplastics, but usually in about 1/8th of cases.