Bones Home > Achondroplasia Dwarfism
Achondroplasia dwarfism is an inherited bone-growth disorder that affects 1 in 15,000 to 40,000 births. In this condition, cartilage has difficulty converting to bone, especially in the long bones of the arms and legs. Commonly associated health problems include breathing disorders, obesity, and crowded teeth. While there is no cure for achondroplasia dwarfism, the symptoms and associated health problems can be managed.
Achondroplasia Dwarfism: An Overview
Achondroplasia dwarfism is one of the most common causes of dwarfism. The term "achondroplasia" is a Greek word that means "without cartilage formation." Characteristics of a person with achondroplasia dwarfism include:
- A short stature with proportionately short arms and legs
- A large head
- A prominent forehead,
- A flattened bridge of the nose.
What Is Achondroplasia Dwarfism?Achondroplasia dwarfism is a bone-growth disorder. Although achondroplasia literally means "without cartilage formation," the problem is not the formation of cartilage. Rather, the problem occurs when the cartilage has difficulty converting to bone, especially in the long bones of the arms and legs.
Cause of Achondroplasia Dwarfism
Most people with achondroplasia dwarfism have average-size parents, which means that the condition is caused by a new mutation in the fibroblast growth factor receptor 3 (FGFR3) gene. This gene is believed to be responsible for achondroplasia dwarfism; however, scientists do not know why this mutation occurs.
(Click FGFR3 Gene for more information about the gene that can cause achondroplasia dwarfism.)
Achondroplasia dwarfism can also be inherited in an autosomal dominant pattern, which means that one copy of the altered gene in each cell is sufficient to cause the disorder. In these cases, one of the parents with achondroplasia dwarfism passes on the FGFR3 gene to the child.
If one parent has achondroplasia dwarfism, children have a 50 percent chance of inheriting the FGFR3 gene. If both parents have achondroplasia dwarfism, children have a one in four chance of inheriting the gene from both parents. Newborns who inherit both genes are considered to have a severe form of achondroplasia, where survival is usually less than 12 months after birth.
(Click Cause of Achondroplasia for more information.)