Achondroplasia

WHAT IS ACHONDROPLASIA?

Achondroplasia (pronounced ay-kon-dro-play-zha) is a genetic condition in which a person is of very short stature because of restricted growth of bones and cartilage. Some conditions which cause restricted growth affect the whole body equally, but the growth of a person with Achondroplasia is 'disproportionate' (i.e. unequal) because growth is most restricted in the long bones of the legs and arms, while the trunk is near to average size.

HOW IS ACHONDROPLASIA PASSED ON?

The pattern of inheritance for Achondroplasia is autosomal dominant. Where one parent has Achondroplasia, there is a 50% (1 in 2) chance of each and every child being affected. If both parents have Achondroplasia, each and every child has a 50% (1 in 2) chance of having Achondroplasia and a 25% (1 in 4) chance of being unaffected.

There is also a 25% (1 in 4) chance of the baby inheriting the Achondroplasia gene from both parents, in which case it will be very severely affected and die soon after birth. However, most people with the condition have no family history of Achondroplasia. They are probably affected because of a spontaneous genetic mutation which took place in the egg or sperm before fertilisation.

A PERSON WITH ACHONDROPLASIA MAY EXPERIENCE SOME, OR ALL, OF THE FOLLOWING:

• The average height for an adult with Achondroplasia is between 1m 12 and 1m 45 (approx. 3'8" to 4'9").
• A person with is of short stature because the bones in the leg are much shorter than average. The rest of the body is affected in different ways - the arms are also very short, the trunk is of nearly average size, the head is slightly enlarged with a flattened nose and a prominent forehead, and the fingers may be short and stubby. The lower legs may be bowed, and curvature of the lower spine can sometimes cause pain and other problems later on in life.

Children with Achondroplasia may take longer to sit, stand and reach other milestones in their physical development than other children. Ear infections are common and as with all children can lead to hearing loss if not treated. Because of the shape of the lower jaw, teeth may be crowded and badly aligned. Some people wrongly assume that a small body means a small brain, but people with Achondroplasia have the same range of intelligence as the general population.

Many of the problems which people with Achondroplasia face are to do with how society treats them rather than with the fact that they have Achondroplasia. The lower legs may be bowed, and curvature of the lower spine can sometimes cause pain and other problems later on in life.

OTHER INFORMATION

Achondroplasia is also known as short-limbed dwarfism. Many people with achondroplasia use and accept the word 'dwarf, but some prefer the terms 'small, little people' or 'people of restricted growth/short stature

Achondroplasia occurs in all races and in both sexes. About 1 in every 25,000 babies born in the UK will have Achondroplasia.

If you are interested in finding out more about Achondroplasia, you can write (enclosing an A5 stamped addressed envelope) to: Restricted Growth Association (RGA), PO Box 4744 Dorchester, DT2 9FA. www.rgaonline.org.uk