Could you tell us a little about a condition called achondroplasia? My sister’s son was born with this. We don’t know anyone else in the family who has this problem, so how does it get started?

Achondroplasia is a genetic disorder that results in a common type of dwarfism. The condition may be inherited. But in most cases (80 per cent), there is a spontaneous mutation of the gene that controls bone and cartilage growth. The cause is unknown. Older age of parents at the time of conception (35 years old or older) may be a risk factor.

Children who are born with this condition have a variety of deformities, including several in the spine. Common spinal manifestations include foramen magnum stenosis, thoracolumbar kyphosis, lumbosacral hyperlordosis, and spinal stenosis.Thoracolumbar kyphosis is a curved mid-lower back from the way the children slump-sit.

Foramen magnum stenosis refers to narrowing of the opening at the base of the skull where the spinal cord exits. Lumbosacral hyperlordosis is an increase in the normal swayback position of the low back area. The more thoracic kyphosis is present, the more the body tries to compensate with increased lordosis. When viewed from the side, the child with these two features combined has a prominent abdomen (belly) and buttocks.

Spinal stenosis (narrowing of the spinal canal) can occur at the cervical (neck) level or in the lumbar (low back) area. There are other manifestations of achondroplasia. The children (and adults) are usually short in height with a characteristic look because of changes in the bones of the face. Children have frequent ear infections. There are some deformities of the arms and legs.