Achondroplasia is a common, nonlethal form of skeletal dysplasia (dysplasia - not normal), or a genetic disorder of bone growth. Depending on who you ask, statistics say that one in 25,000 to one in 60,000 births will result in Achondroplasia. Achondroplasia is one of the oldest recorded birth defects, dating back to the Roman Empire. It is characterized by abnormal body proportions — affected individuals have arms and legs that are very short, while the torso is more nearly normal size, and in some cases individuals have larger heads due to "frontal bossing".
Before beginning to walk, a baby with achondroplasia often develops a small hump (kyphosis) on his lower back. This is due to poor muscle tone, and usually goes away after the child starts walking. Once walking, the child usually develops a markedly curved lower spine (lordosis or sway- back), and the lower legs often become bowed. The feet are generally short, broad and flat.
Achondroplasia is caused by an abnormal gene located on one of the chromosome 4 pair (humans have 23 pairs of chromosomes). In some cases, a child inherits achondroplasia from a parent who also has the condition. If one parent has the condition and the other does not, there is a 50 percent chance that their child will be affected. If both parents have achondroplasia, there is a 50 percent chance that the child will inherit the condition, a 25 percent chance that the child will not have it, and a 25 percent chance that the child will inherit one abnormal gene from each parent and have severe skeletal abnormalities that lead to early death. A child who does not inherit the gene will be completely free of the condition, and cannot pass it on to his or her own children.In more than 80 percent of cases, however, achondroplasia is not inherited but results from a new mutation (change) that occurred in the egg or sperm cell that formed the embryo. The parents of children with achondroplasia resulting from new mutations are usually normal-sized. The gene that causes this disorder was only discovered in 1994, so much research is still being done to learn more about it. The gene is one of a family of genes that makes proteins called fibroblast growth factor receptors. Scientists have recently linked these genes with several skeletal disorders.The gene that causes this disorder was discovered in 1994, a mere 13 years ago. While scientists are eagerly studying these mutations, there is much controversy from society at the outcome of the studies.
Since the discovery, many couples have chosen to terminate pregnancies because of this. A few notes: Intelligence is entirely normal in people with achondroplasia. The term "midget" is considered offensive in this day and age. The acceptable terms for a person with any type of dwarfism are person with dwarfism, little person, LP, and person of short stature.
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*I got this from The Johnson's blog here, which I think explains the condition quite well*
4 months ago
