What is Achondroplasia?
Achondroplasia is a genetic bone disorder that affects one child in 20,000. It is the most common type of dwarfism in which the child has short arms and legs compared to body length. The head is often large, the body is of normal size. The average height of adult men with achondroplasia is 132 cm, and the average height of adult women with achondroplasia is 125 cm.
What are the symptoms of achondroplasia?
Here are the most common symptoms of achondroplasia, but each child may present differently:
- short arms and legs, upper arms and thighs shorter than forearms and lower legs
- large head size with a protruding forehead and a flattened bridge of the nose
- crowded or misaligned teeth
- curvature of the lower spine: a condition also called lordosis, which can lead to kyphosis, or the development of a small bump near the shoulders, which usually resolves after the child begins to walk
- small spinal canals: can lead to compression of the spinal cord during adolescence (sometimes children with achondroplasia die suddenly in infancy or in infancy in their sleep due to compression of the upper limbs of the spinal cord, which interferes with breathing)
- curved shins
- short and wide flat feet
- extra space between the middle and ring fingers (also called a trident)
- low muscle tone and joint mobility
- frequent infections of the middle ear, which can lead to hearing loss
- normal intelligence
- delayed developmental milestones such as walking (which can happen between 18 and 24 months)
What causes achondroplasia?
In some cases, a child inherits achondroplasia from a parent with the condition, but in most cases - about 80% - it is caused by a new mutation in the family. This means that the parents are of average height and do not have the abnormal gene.
However, people with achondroplasia have a 50% chance of passing the gene to the child, resulting in the disease.
If both parents have achondroplasia, there is a 50% chance of having a child with achondroplasia, a 25% chance that the child will not inherit the gene and be of average height, and a 25 percent chance that the child will inherit one abnormal gene from each parent, which can lead to severe skeletal problems that often result in early death.
Fathers over 45 are more likely to have children with certain genetic disorders, including achondroplasia. At present, researchers have not found any specific mutations in spermatozoa associated with the disease.
How is achondroplasia diagnosed?
Achondroplasia can be diagnosed before birth with a fetal ultrasound or after birth with a complete medical history and physical examination. DNA testing is available before birth to confirm fetal ultrasound findings for parents who are at increased risk of having a baby with achondroplasia.
What are the treatment options for achondroplasia?
There is currently no way to prevent achondroplasia, as most of the time it results from unexpected new mutations. Doctors may treat some children with growth hormone, but this does not significantly affect the growth of a child with achondroplasia. In some specific cases, surgical procedures to lengthen the legs may be considered.
It is very important to check for bone abnormalities, especially in the back area. These problems can lead to difficulty breathing and leg pain. Kyphosis, or "humped back", may need to be corrected surgically if it does not correct itself when your child starts walking. There is another surgical procedure to help bend the legs.
Some children may have ear infections. They should be treated as soon as possible to prevent hearing loss. Dental problems may require treatment by an orthodontist.