Achondroplasia

All people with one of the gene mutations in the FGFR3 gene that cause achondroplasia will have symptoms. Not all people will have every possible symptom, but all will have shorter height than the general population.

Every person with achondroplasia is expected to be much shorter than average. A man with achondroplasia will be, on average, about 4 feet 4 inches tall and a woman will grow to around 4 feet 1 inches. These are averages though; some people will be taller and some shorter.

People with achondroplasia will be much shorter than people in the general population. The trunk, or torso, of people with achondroplasia is average sized, but the limbs (legs and arms) are shorter than average. The length of the femur (thighbone) and humerus (upper arm bone) are particularly shortened. This can lead to decreased range of motion at the elbows. Often times, people with achondroplasia have shorter than average fingers as well. People with achondroplasia often have a larger head size (macrocephaly) and a prominent forehead.

There are other symptoms associated with achondroplasia. Recurrent ear infections are common in childhood and may require ear tubes to be placed. Weight control and problems breathing while sleeping (apnea) can be seen. Many children with achondroplasia can develop tibial bowing (curving of the part of the leg between the knee and foot). Spinal abnormalities like lordosis (pronounced inward curve in their lower back) and kyphosis (outward bending curve of the upper spine) can develop too. These conditions can cause back pain. Two more serious spinal complications are foramen magnum stenosis and spinal stenosis. Foramen magnum stenosis is when the base of the skull is too narrow for the spinal cord to pass through. It is most often diagnosed between birth and three years of age, but children as late as eight have been diagnosed with this condition. Foramen magnum stenosis can cause low muscle tone, breathing problems, headaches, or sudden death. This condition can be treated by surgery. Spinal stenosis is when the spinal canal narrows. It can lead to pain and, in extreme cases, can make it difficult to walk.

A less common symptom for people with achondroplasia is hydrocephalus. Hydrocephalus occurs when fluid builds up in the brain. If this happens, head size grows and it can affect the brain. The greatest chance to develop hydrocephalus for people with achondroplasia is before the age of 2, but it can occur later in life as well.

Overall, there are some common features shared by almost all individuals with achondroplasia, but there are also differences between affected individuals. For more information about the signs and symptoms of achondroplasia, find a reliable resource such as the review of achondroplasia by the Midwest Regional Bone Dysplasia Clinics.

There is one other form of achondroplasia known as SADDAN (severe achondroplasia with developmental delay and acanthosis nigricans) syndrome. SADDAN is significantly more rare than achondroplasia and is caused by a different change in the same gene.

All people with achondroplasia have symptoms from birth, but some symptoms can be so subtle initially that it can take several months to diagnose. Some additional symptoms may not appear until childhood, and the symptoms may be more or less severe in specific people.

All babies with achondroplasia are born with short bones. There are some symptoms that do not occur or develop until later though. Breathing problems, like apnea, where breathing stops or slows below regular rhythm, can occur. Recurrent ear infections are common as well. Weight control is a problem for many people with achondroplasia as well. Many children with achondroplasia will develop bowed legs. Spinal abnormalities like lordosis and kyphosis can develop as well. People with lordosis have pronounced inward curve in their lower back. People with kyphosis have an outward bending curve to their upper spine. These conditions can cause back pain. Two more serious spinal complications are foramen magnum stenosis and spinal stenosis. Foramen magnum stenosis is when the base of the skull is too narrow for the spinal cord to pass through. It is most often diagnosed between birth and three years of age, but children as late as eight have been diagnosed with this condition. Foramen magnum stenosis can cause low muscle tone, breathing problems, headaches, or sudden death. This condition can be treated by surgery. Spinal stenosis is when the spinal canal narrows, and it can lead to pain and can make it difficult to walk in extreme cases. A less common symptom for people with achondroplasia is hydrocephalus. Hydrocephalus is when fluid builds up in the brain. If this occurs, head size grows and it can affect the brain.

Overall, there are some common features shared by almost all individuals with achondroplasia, but there are also differences between affected individuals. For more information about the signs and symptoms of achondroplasia, find a reliable resource such as the review of achondroplasia by the Midwest Regional Bone Dysplasia Clinics.

There are many other types of dwarfism that share some similarities to achondroplasia. Dwarfism is a type of condition that causes a person to be of much shorter than average height. Achondroplasia is a specific form of short-limbed dwarfism, which implies that people with the condition have shorter arms and legs than the general population. Achondroplasia is the most common form of dwarfism, but there are many other forms of short-limbed dwarfism that share some features with achondroplasia. Hypochondroplasia is the condition most similar to achondroplasia. The symptoms of hypochondroplasia are generally less severe than those of achondroplasia. Average height for males with hypochondroplasia ranges from 4 feet 6 inches to 5 feet 5 inches and 4 feet 2 inches to 4 feet 11 inches for women, which is taller than average heights in achondroplasia. Mutations in the FGFR3 gene can cause hypochondroplasia as well.

There are dozens of other forms of short-limbed dwarfism that overlap with achondroplasia somewhat in their features. For a list of some other conditions whose features overlap with achondroplasia, consult a reference such as the Gene Facts review on diagnosis of achondroplasia.