Who is affected by achondroplasia dwarfism

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What Is Toulouse-Lautrec Syndrome? Medically reviewed by Karen Gill, M. What Is Caudal Regression Syndrome? Medically reviewed by Mia Armstrong, MD. Krabbe Disease. Fibroblasts are cells that make the collagen and other structural materials in our tissues and bones. They also play an important role in wound healing. A growth factor is a protein that stimulates cell growth. A receptor is a molecule on the surface of cells that binds with other molecules outside of the cell.

This enables the cell to respond to external stimuli such as growth factors. The FGFR3 protein spans the cell membrane so that one end is inside the cell and the other is outside. This allows the protein to interact with growth factors outside the cell and receive signals for growth and development.

FGFR3 protein in bone cells helps control bone growth by limiting a process called ossification, which controls the formation of bone from cartilage. The bones of embryos are made largely of cartilage, so they are soft. Ossification uses calcium to create hard, strong bone, as the child grows. This results in the FGFR3 protein being absent or damaged so that it cannot interact with external growth factors and therefore cannot control ossification.

This results in problems during bone development where cartilage fails to turn into bone. Symptoms Due to poor bone development, the bones are shortened, particularly in the thigh and upper arms, a condition known as rhizomelia.

The thigh and upper arms are more affected because they have longer bones and larger growth plates regions of the bones where growth occurs. The lower legs and forearms are affected to a lesser degree because their growth plates are smaller. The hands and feet are also short with unusual separation between the third and fourth digits. Affected individuals reach a maximum height of cm four feet. The torso usually develops to its proper size but the head may be larger than normal with a prominent forehead and flat nose.

Affected children have delayed development and often take longer to learn to sit, crawl and walk than their unaffected peers. Spinal stenosis is associated with pain, tingling, and weakness in the legs that can cause difficulty with walking.

Another uncommon but serious complication of achondroplasia is hydrocephalus, which is a buildup of fluid in the brain in affected children that can lead to increased head size and related brain abnormalities. Achondroplasia is the most common type of short-limbed dwarfism. The condition occurs in 1 in 15, to 40, newborns. Mutations in the FGFR3 gene cause achondroplasia.

The FGFR3 gene provides instructions for making a protein that is involved in the development and maintenance of bone and brain tissue. Two specific mutations in the FGFR3 gene are responsible for almost all cases of achondroplasia.

Researchers believe that these mutations cause the FGFR3 protein to be overly active, which interferes with skeletal development and leads to the disturbances in bone growth seen with this disorder. Achondroplasia is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

About 80 percent of people with achondroplasia have average-size parents; these cases result from new mutations in the FGFR3 gene. In the remaining cases, people with achondroplasia have inherited an altered FGFR3 gene from one or two affected parents.

Individuals who inherit two altered copies of this gene typically have a severe form of achondroplasia that causes extreme shortening of the bones and an underdeveloped rib cage. These individuals are usually stillborn or die shortly after birth from respiratory failure. Genetics Home Reference has merged with MedlinePlus.

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