Achondroplasia

Unless a person has significant symptoms of achondroplasia, there is no need to test other relatives. It is not possible to be a carrier of achondroplasia like it is for some other conditions, such as cystic fibrosis or sickle cell disease.

To find other people with achondroplasia, consider joining local support or activism-related groups for people with achondroplasia. Additionally, consider asking your doctor if he or she knows of any individuals or families with achondroplasia.

Support group websites can help connect people with achondroplasia to others with the same diagnosis. Some such support groups are listed here:

To confirm that someone has achondroplasia and not a different genetic cause for their short stature and health issues there are a few different types of tests:

Testing
Before birth
If there are some findings on the ultrasound or sonogram that makes the doctor think about achondroplasia, depending on how far along in the pregnancy the woman is, they may suggest a special genetic testing on a sample of amniotic fluid. This testing would be collected through an amniocentesis which is an invasive test. That would require planning to make sure the correct test was done because there are several testing options from panels like the prenatal skeletal dysplasia testing panel at http://www.genedx.com/test-catalog/disorders/achondroplasia-ach/ or reading through the FGFR3 in a sequencing test.

Of course, if there is a unknown change in the FGFR3 gene resulting in achondroplasia in the family, they can just test for that gene change.

After birth

A diagnosis of achondroplasia is usually made not through genetic testing but by physical examination and review of X-rays. There is a very specific set of criteria looking at health issues, symptoms, and measurements that doctors use to determine if a person has achondroplasia.

Genetic testing can confirm a diagnosis of achondroplasia, but is not required for the diagnosis. This is done by obtaining a sample of DNA from a person, typically through a blood draw. The sample is first tested for the two most common changes in the FGFR3 gene that are associated with achondroplasia. One of these two changes is present in about 99% of people with a clinical diagnosis of achondroplasia. Genetic laboratories can also look at the entire FGFR3 gene (gene sequencing) to detect much more rare genetic changes. This approach may be beneficial when it is unclear whether a diagnosis of hypochondroplasia or achondroplasia is more appropriate. There are several labs that do this type of testing and there is a list on the Genetests site.

There is also the option of a genetic testing panel that tests for achondroplasia AND other causes of dwarfism. A good example of that is the [link url=" http://geneticslab.emory.edu/tests/MM171″ target=”_blank”>Disproportionate Short Stature: Sequencing Panel at EGL Genetics. Of course, if there is a unknown change in the FGFR3 gene resulting in achondroplasia in the family, they can just test for that gene change.

Regular Checkups

If someone has achondroplasia there are important things to check on a regular basis. Generally for newly diagnosed child, it is recommended that they have:

Women with achondroplasia have a smaller pelvic size than the general population. For this reason, Caesarian section delivery is the recommended delivery method. It is recommended that pregnant women with achondroplasia be followed by a high risk obstetrician known as a maternal-fetal medicine doctor (MFM). To find an MFM near you, consult the Society for Maternal-Fetal Medicine’s website.

Depending on the severity of the sleep apnea, treatment recommendations may vary. Weight reduction or use of a continuous positive airway pressure (CPAP) machine during sleep may be suggested. Surgical intervention, like adenotonsillectomy (removal of adenoids and tonsils) or tracheostomy (breathing tube) for severe circumstances may also be discussed.

Which specialists a person with achondroplasia should see will vary from person to person, and will depend on a person’s particular symptoms. At the minimum, consultation with a geneticist, an orthopedist, and a neurologist can help determine what other referrals are recommended. If possible, visiting a clinic that specializes in skeletal dysplasias such as achondroplasia can help to assure that you are receiving the highest quality of care. To view more information about recommendations about which medical specialists and individual with achondroplasia might see, and how frequently, review the Gene Facts regarding management of achondroplasia.

There are many conditions that fall into the category of dwarfism. There are some differences in physical examination and X-ray findings that help to determine what type of dwarfism a person has. In fact, there is a specific set of criteria that can be used to make or rule out the diagnosis of achondroplasia in a particular person. In general 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 thighbone and the upper arm bone are particularly shortened. The presence of these characteristics allows medical professionals to differentiate achondroplasia from other forms of dwarfism. Furthermore, if genetic testing is performed and one of the two common changes in the FGFR3 gene associated with achondroplasia is present, the diagnosis of achondroplasia can be certain.

Because differentiating forms of dwarfism from one another can be difficult due to their overlapping features, it is recommended that a team of specialists be involved in evaluating an individual before a diagnosis is made. These specialists may include a radiologist, an orthopedist, a geneticist and/or a genetic counselor. If you wish to speak with a specialist about how achondroplasia is differentiated from other forms of dwarfism, consider contacting a genetic counselor to speak further or make an appointment. You can find a local genetic counselor on the National Society of Genetic Counselors’ Find a Genetic Counselor website.

People with achondroplasia are expected to have a normal life expectancy.

When a couple, neither of whom have achondroplasia, have a baby with achondroplasia, the genetic change occurred for the first time in that baby. This is known as a de novo gene change. When a genetic change is de novo, it is unlikely to occur again in a future pregnancy. There are rare instances, however, of an unaffected couple having more than one affected baby. This is due to a condition known as germline, or gonadal, mosaicism. In gonadal mosaicism, a gene change can be found in the reproductive cells (sperm or egg cells) of an individual that is not present in the cells of the rest of their body. Individuals with germline mosaicism can produce multiple egg or sperm cells that carry a gene change. Although low, therefore, there is a slightly increased risk for an unaffected couple to have subsequent offspring with achondroplasia. This chance likely does not exceed 1% with each pregnancy.

When both parents have achondroplasia, there is a 50% chance that any child they have will have achondroplasia. There is a 25% chance that any child will not inherit achondroplasia. This means that the child inherited neither parent’s changed copy of the FGFR3 gene. There is also a 25% risk that any child could inherit both parents’ changed FGFR3 genes. Babies with two copies of the FGFR3 gene mutation are much more severely affected and have a low chance of survival due to their severe symptoms.

Achondroplasia is a genetic type of dwarfism. Dwarfism is a type of condition that causes a person to be of much shorter than average height. Achondroplasia is specifically a 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.

Genetic changes in the FGFR3 gene can lead to achondroplasia. People with achondroplasia have poor cartilage to bone conversion. Cartilage is the bendable, but strong material that makes up your ears and the tip of your nose. When babies are first developing, much of the skeleton is initially made of cartilage. This cartilage then needs to transform into bone in a process named ossification. When someone has a genetic change in the FGFR3 gene causing achondroplasia, ossification does not occur at the usual rate. This process is especially slowed in the legs and the arms. This causes people with achondroplasia to have shorter arms and legs than the average person.

To learn more about achondroplasia, contact a genetic counselor for more information. Use the Find a Genetic Counselor page at the National Society of Genetic Counselors’ website to locate a genetic counselor near you.

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.

People with achondroplasia have poor cartilage to bone conversion. Cartilage is the bendable, but strong material that makes up your ears and the tip of your nose. When babies are first developing, much of the skeleton is initially made of cartilage. This cartilage then needs to transform into bone in a process named ossification. The FGFR3 gene codes for making a protein that is involved in the ossification process. When someone has a genetic change in the FGFR3 gene causing achondroplasia, ossification does not occur at the usual rate. This process is especially slowed in the legs and the arms. This leads to people with achondroplasia having shorter arms and legs than the average person. To learn more about how the FGFR3 gene causes achondroplasia, refer to a reliable website such as Genetics Home Reference.

Changes in the FGFR3 gene can lead to achondroplasia. Around 99% of people with achondroplasia have one of two specific genetic changes ("mutations") in the FGFR3 gene. These two gene changes in FGFR3 that cause achondroplasia are known as: c.1138G>A (p.Gly380Arg) and c.1138G>C (p.Gly380Arg).

Over 99% of people with achondroplasia have one of two genetic changes in the FGFR3 gene: c.1138G>A (p.Gly380Arg) or c.1138G>C (p.Gly380Arg). Other changes in to the FGFR3 gene may be classified as a "variant of uncertain significance." This means that it is a genetic change that we do not fully understand and that we are not quite sure if or how it affects the body. It may cause achondroplasia and it may not. We need more data to be sure. A genetic counselor or geneticist may be able to help explain what this result means for your particular situation. To find a genetic counselor near you, visit the National Society of Genetic Counselors Find a Genetic Counselor website.

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.

After an initial diagnosis of achondroplasia in a newborn baby, the following steps are recommended:

Although the risk for obesity is higher for people with achondroplasia than in the general population, the same strategies should be used for people with achondroplasia as for those without. It is important to start good diet and exercise practices in childhood. Height to weight charts designed specifically for children with achondroplasia have been developed to help people stay healthy. As of December 2015, no body mass index (BMI) calculators have been created for people with achondroplasia. For people with achondroplasia, current BMI calculations will be a misrepresentation of the person’s actual health. Growth charts for individuals with achondroplasia can be found in the American Academy of Pediatrics’ publication, Health Supervision for Children With 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.

As of June 2016, achondroplasia is not on the Recommended Uniform Screen Panel (RUSP). The RUSP is created by the Health Resources and Services Administration, and states use this list to guide what conditions they screen for on newborn screening. It should be noted that almost all babies with achondroplasia will be suspected as having achondroplasia or another form of dwarfism after initial examination by a pediatrician.

There are two types of genetic testing available for achondroplasia. Targeted genetic testing looks for the two most common changes in the FGFR3 gene that are associated with achondroplasia. This testing finds the mutation in around 99% of people with achondroplasia. Genetic laboratories can also look at the entire FGFR3 gene (gene sequencing) to detect genetic changes. This approach may be beneficial when it is unclear whether a diagnosis of hypochondroplasia or achondroplasia is more appropriate. Generally though, it is recommended to begin with targeted genetic testing.

There is clinical research being conducted on achondroplasia. The website ClinicalTrials.gov can provide up-to-date information on research being conducted on achondroplasia. Also, there is an International Skeletal Dysplasia Registry (ISDR) at UCLA. People with achondroplasia can choose to participate in this registry, and the ISDR’s website also lists many recent research publications on skeletal dysplasia. The Little People of America website also provides information about research being conducted on achondroplasia.

There is not an FDA-approved general treatment for achondroplasia at this time, but there are some in clinical trials. There are some treatments available for certain symptoms and there are medical management guidelines that should be followed. Combinations of these two practices can improve the quality of life of people with achondroplasia. Limb lengthening is a controversial technique available to increase height, but it is not commonly done in North America, and there are numerous considerations to be made about the potential benefits and risks before limb lengthening is pursued.

You can see information about different types of treatment that individuals with achondroplasia may undergo by reviewing the Gene Facts web page about management of achondroplasia.

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.

Should hydrocephalus create pressure inside the skull on the brain, an individual should see a neurosurgeon for evaluation. Generally, the preferred procedure to treat hydrocephalus in achondroplasia is ventriculoperitoneal shunting over third ventriculostomy.

Although achondroplasia is a genetic condition, when a person has achondroplasia, it is not always inherited from a parent. In fact, only about 20% of people with achondroplasia inherited it from either their mom or dad. The other 80% of the time, achondroplasia is a new diagnosis in the family and was not inherited from either parent. In this case, there was a spontaneous change in the FGFR3 gene carried by the egg or sperm cell that helped conceive that individual. That gene change is present from the time the baby is conceived and causes the abnormal bone development seen in achondroplasia. Because the affected individual carries that gene change in all of the cells of their body, their own future offspring are at risk for achondroplasia.

If a person with achondroplasia has a baby with a person who is unaffected, there is a 50% chance that any offspring will have achondroplasia. This means that when one parent is affected there is also a 50% chance that the baby will not have achondroplasia.

When both parents have achondroplasia, there is still a 50% chance that any child they have will have achondroplasia. There is a 25% chance that any child will not inherit achondroplasia. This means that the child inherited neither parent’s changed copy of the FGFR3 gene. There is also a 25% risk that any child whose parents both have achondroplasia could inherit both parents’ changed copy of the FGFR3 gene. Unfortunately, babies with two copies of the FGFR3 gene mutation do not survive.

There are multiple ways to help this community through financial contribution. Growing Stronger helps to fund research on achondroplasia and other types of dwarfism. You can also donate to Skeletal Dysplasia Research at UCLA. People may also choose to donate to support groups, like:

A diagnosis of achondroplasia is typically made not through genetic testing but by physical examination and review of X-rays. There is a very specific set of criteria doctors use to determine if a person has achondroplasia. To learn more about the diagnostic criteria for achondroplasia, review the Gene Facts information sheet on the diagnosis of achondroplasia.

Genetic testing can confirm a diagnosis of achondroplasia, but is not required for the diagnosis. This is done by obtaining a sample of DNA from a person, typically through a blood draw. The sample is first tested for the two most common changes in the FGFR3 gene that are associated with achondroplasia. One of these two changes is present in about 99% of people with a clinical diagnosis of achondroplasia. Genetic laboratories can also look at the entire FGFR3 gene (gene sequencing) to detect much more rare genetic changes. This approach may be beneficial when it is unclear whether a diagnosis of hypochondroplasia or achondroplasia is more appropriate. Generally though, it is recommended to begin with targeted genetic testing. To discuss arranging genetic testing for achondroplasia, contact a local genetic counselor. You can find one through the National Society of Genetic Counselors Find A Genetic Counselor search page.

The website ClinicalTrials.gov can provide up-to-date information on research being conducted on achondroplasia. Also, there is an International Skeletal Dysplasia Registry (ISDR) at UCLA. People with achondroplasia can choose to participate in this registry, and the ISDR’s website also lists many recent research publications on achondroplasia and other skeletal dysplasias.

The Little People of America website offers information on clinics that specialize in skeletal dysplasias, the broad category of bone issues and dwarfism that achondroplasia falls in, across the United States. It also provides some information about clinics in Canada and Europe.

The exact number of babies born with achondroplasia is not known. It is believed though that about every 1 in 15,000 to 1 in 40,000 babies born have achondroplasia.

Some populations appear to have a higher incidence of achondroplasia. For instance it is estimated to occur in about 1 case in 6400 births in Denmark and about 1 case in 10000 births in Latin America. No particular race has been documented to be more commonly affected.

When both parents have achondroplasia, there is a 1 in 4 risk that any baby conceived would inherit both parents’ FGFR3 gene mutations. This combination of two FGFR3 mutations is not compatible with life. There are some options for parents. Parents can pursue preimplantation genetic diagnosis (PGD). With PGD, using in vitro fertilization and genetic testing technologies, parents can choose to not implant embryos that have two FGFR3 mutations into the mother’s uterus. PGD is relatively expensive and may not be covered by insurance. Furthermore, it is not guaranteed to lead to pregnancy every time nor is it guaranteed to ensure having babies that are unaffected with the fatal form of achondroplasia.

Another option for parents hoping to avoid having offspring with the fatal form of achondroplasia caused by inherited the abnormal FGFR3 gene change from both parents is prenatal diagnosis. DNA from the baby can be tested during the pregnancy to determine how many FGFR3 mutations a baby has. This can be done in the first trimester (around 10-13 weeks) by a procedure called chorionic villus sampling or in the second trimester (after 15 weeks) by amniocentesis.

To learn more about PGD or prenatal diagnosis, contact a genetic counselor near you. To find a genetic counselor near you, visit the National Society of Genetic Counselors Find a Genetic Counselor website.

There is not anything in particular that makes the symptoms of achondroplasia worse, but there are some precautions that should be taken to prevent injury. For example, children with achondroplasia are at higher risk to have a spinal cord injury, particularly at the craniocervical junction (skull to spine connection on the spinal cord). Avoiding certain activities, like contact sports, trampoline bouncing, diving, and gymnastics (particularly the vault) can reduce risk of these types of injury. To learn more about how to avoid injuries for individuals with achondroplasia, refer to a reliable source such as the Gene Review on achondroplasia.

Achondroplasia itself does not cause a delay in the development of social skills. Children who feel or who are perceived as different from their peers, however, can sometimes have difficulty with socialization. This includes children who are shorter than average due to achondroplasia. Helping your child understand and feel comfortable with their diagnosis of achondroplasia may help them educate and deal with other children. Being able to answer other children’s questions might make new interactions easier. Little People of America can help new parents learn about how to help children with achondroplasia grow socially. Referral to a psychologist may help people wanting more support.

Achondroplasia does not cause learning problems. The majority of people with achondroplasia do have normal intelligence. Exactly how smart a person with achondroplasia is will vary as it does for people without achondroplasia.

Achondroplasia is also referred to as achondroplastic dwarfism. Sometimes it is abbreviated as "ACH". It should be noted that there are many terms out there that are used to describe not only people with achondroplasia, but also those with other forms of dwarfism. These include: dwarf, little person, LP, and person of short stature. It is very important to know that the term "midget" has fallen out of favor and should never be used to describe a person with achondroplasia or other type of dwarfism as it is considered an offensive term. If you want to know the proper names used to refer to achondroplasia, or if you want to know if a specific term can mean the same thing as achondroplasia, try looking at a reliable website such as Genetics Home Reference or the Little People of America website.

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.

The Dwarf Athletic Association of America provides opportunities for athletic competition for people with short stature. There are volunteer opportunities as well.

There are some great support groups available for people with achondroplasia and their families. There are many support groups that serve different countries and regions throughout the world. A few are listed below.

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.

There are some ways to increase the height of people with achondroplasia. Some research has been conducted to see if growth hormone therapy will alter adult height in patients with achondroplasia. Only minimal increases are noticed when using this therapy. Limb lengthening is a technique that has been used to increase height with more success. An additional 12-14 inches of height can be added when this process is implemented. It is not recommended to begin until a child understands the procedure and its impact. In North America, limb lengthening is not commonly done. There are numerous considerations to be made about the potential benefits and risks before limb lengthening is pursued.