ACHONDROPLASIA IN CHILDREN
What is achondroplasia?
Achondroplasia is derived from the Greek word ?without cartilage formations?. In patients with achondroplasia only a small amount of cartilage forms bones leading to short bones and reduced height. Achondroplasia leads to relatively normal torso and short arms and legs (disproportionate short stature). The average adult height in achondroplasia is about 4 feet for both men and women.
What are the signs and symptoms of achondroplasia?
In a child with achondroplasia, the upper arms and thigh are more shortened than the forearms and lower legs. Generally, the head is large. Teeth may be crowded and upper & lower teeth may be poorly aligned. A person with achondroplasia usually has a relatively straight upper back with markedly curved lower spine. Hands are short with stubby fingers that easily bend backward due to weakened joints. Lower legs may become bowed and feet are generally short, broad and flat. Because of large head, short arms and legs and loose joints, a baby with achondroplasia is slow to sit, stand and walk alone. However intelligence is normal.
Patients have frequent ear infections which can lead to mild to moderate hearing loss.
What is the diagnosis of achondroplasia?
Achondroplasia is a genetic disorder. It is an autosomal dominant disorder i.e., a child inherits achondroplasia from a parent who has the condition. If one parent has achondroplasia and the other one does not, then with every pregnancy there is a 50 percent chance that the child will be affected. If both parents have achondroplasia, there is a 50 percent chance that the child will inherit the condition, 25 percent chance that the child will not have it and 25 percent chance that the child will inherit one abnormal gene from each parent and have severe skeletal abnormalities that lead to early death.
In most cases (over 75 percent), achondroplasia is not inherited but due to a new mutation. Parents of such children are normal and their chance of having a second child with achondroplasia is extremely small.
Diagnosis of achondroplasia is based on clinical signs and symptoms and specific features on X-rays. Specific mutation can be checked for by DNA analysis.
What the complications of achondroplasia?
The most common complication occurs in adulthood is spinal cord compression leading to paralysis of legs requiring surgery to relieve the pressure.
Some children may die suddenly in infancy due to difficulty in breathing due to compression of the upper end of the spinal cord. Breathing problems may occur due to small chest size, large tonsils and small facial structure. In some children excess fluid may accumulate in the brain (hydrocephalus) for which surgery may be required.
How is achondroplasia diagnosed?
Xrays are used to confirm the diagnosis of achondroplasia. It will show large skull with a narrow foramen magnum and relatively small skull base, short, flattened vertabral bodies with relatively large intervertebral disk height and narrow spinal canal. The ribs are short with cupped anterior ends.
What is the treatment of hydrocephalus?
Currently, there is no cure for achondroplasia. However complications such as ear infections, spinal cord compression and hydrocephalus need to be treated as and when required.
Can achondroplasia be prevented?
The diagnosis of achondroplasia in the unborn child can be made with certainty if one or both parents have the condition. In most situations, in which parents have normal height, the diagnosis can only be suspected based on observation of disproportionately short limbs in the fetus by ultrasound. DNA testing for mutation can also be done.
Last updated on 16-04-2007