Achondroplasia

What are the signs and symptoms of achondroplasia?

People with achondroplasia have about the same life expectancy and intellectual ability as the general population. Certain signs and symptoms can appear at various stages of a child’s life.

A prenatal ultrasound can detect some signs of achondroplasia, but many may not be noticeable until the third trimester. These signs include:

• Growth in the long bones of the arms and legs that doesn’t keep pace with head growth
• Disproportionately large head with a prominent forehead
• Excess amniotic fluid (fluid that surrounds and protects your baby in the uterus)
• Extra space between the middle and ring fingers, also called trident hand

Signs that may not appear until after your child is born include:

• Bowed legs
• Short arms and legs, especially in the upper arms and thighs
• Flattened nose bridge and crowded, crooked teeth
• Lordosis (inward curving of the lower spine) or kyphosis (outward curving of the upper spine)
• Narrowed vertebrae (spine bones), which may lead to spinal cord compression
• Low muscle tone and loose joints

Signs that appear later in childhood include:

• Frequent ear infections that may lead to hearing loss
• Delayed motor (movement) development, such as learning to walk later than usual
• Slow or stopped breathing (apnea) for short periods

What tests are used to diagnose achondroplasia?

We offer prenatal genetic screening and testing that may detect achondroplasia in the first trimester, which is much earlier than an ultrasound can detect it. Our genetic counselors meet with you to discuss possible risk and genetic screening options.

During your pregnancy, your doctor may see signs of achondroplasia in a fetal ultrasound. You may have an amniocentesis, a test that detects genetic problems in an unborn baby, to confirm a diagnosis. In this test, doctors insert a needle through your belly into your uterus to take a small sample of amniotic fluid for analysis.

Our fetal care specialists can also diagnose achondroplasia after your baby is born, using:

• A physical exam
• Genetic testing
• X-rays to examine the long bones

How is achondroplasia treated?

There is no achondroplasia treatment for babies before birth. We may be able to diagnose achondroplasia or suspect that your baby has the condition before birth. If so, you will have more ultrasounds to monitor the size of the fetus’s head and overall growth. If the head grows significantly larger, you may need to deliver via cesarean section.

If you have achondroplasia, we monitor you closely throughout your pregnancy. The risk of stillbirth or dangerously high blood pressure (preeclampsia) is higher for mothers with achondroplasia. You may have difficulty breathing during pregnancy as your baby grows and presses against your lungs. We recommend that mothers with achondroplasia deliver via cesarean section.

Most newborns who have achondroplasia don’t need special medical treatment and can receive care in the regular nursery. Soon after birth, we recommend that your baby have these tests:

• X-rays to help confirm a diagnosis
• A sleep study to check for sleep apnea, which increases the risk of sudden infant death syndrome (SIDS)
• Head and body measurements to assess growth and check for hydrocephalus (fluid buildup in the brain)

As your child grows, they may need monitoring and treatment to manage complications and symptoms of achondroplasia. Treatments and testing include:

• Continued head and body measurements to track growth and monitor for hydrocephalus in the first two years
• Treatment for frequent ear infections to prevent hearing loss
• Speech-language therapy to improve speech, language, thought processing and socializing
• Physical therapy to help with delayed motor development
• Dental and orthodontic care to improve teeth alignment
• Orthopedic spine and back care to correct spine problems and bowed legs
• A variety of adaptive accommodations, such as foot and seating support with school desks, and aids for managing heavy doors and high doorknobs

At Children's Hospital Colorado, we offer growth hormone treatments through research studies that aren’t always available at other fetal centers. These treatments may help your child grow a few inches taller as they reach adulthood. If your baby is eligible, they can join the study and start receiving treatment soon after birth.

Why choose us for achondroplasia treatment?

Learning that your baby may have achondroplasia can be distressing. At the Colorado Fetal Care Center, our specialists will ensure that you have a safe pregnancy and delivery, if you deliver at our hospital. After your baby is born, we help develop a customized care plan. Our dedicated Achondroplasia Clinic includes pediatric experts from across our hospital who have experience caring for children with achondroplasia.

Our multidisciplinary care allows your child to see all their providers in one visit to save you time and improve their care. Read about our fetal specialists and surgeons and their teams who help your family through this journey to a healthy delivery.

Helpful resources

• National Institutes of Health, Genetic and Rare Diseases Information Center: Achondroplasia
• National Institutes of Health, U.S. National Library of Medicine: Achondroplasia
• Little People of America 
• Magic Foundation 

Could I have another child with achondroplasia?

If neither parent has achondroplasia, it’s very unlikely that you would give birth to another child with the condition. The risk that your other children would have achondroplasia is less than 1%.

If I have achondroplasia, what are my chances of having a child with the condition?

A person who has achondroplasia has a 50% chance, with each pregnancy, of having a child with the condition.

What are the ultrasound findings in achondroplasia?

Prenatal ultrasounds can show:

• Shortened long bones of the arms and legs, usually at 26 weeks’ gestation or later
• Disproportionately large head with a prominent forehead
• Fingers that are the same length with a fork-like appearance (trident-shaped hand)

Do I have to undergo amniocentesis or chorionic villus sampling before delivery?

No, you may not need to have an amniocentesis or CVS during pregnancy. However, the information can help your doctor plan your and your baby's care during pregnancy, delivery and afterward. Some parents wish to confirm the diagnosis so they know what to expect and to prepare for delivery and some families wait until after birth to do genetic testing.

Did I do anything to cause achondroplasia in my baby?

Nothing that either parent does can cause achondroplasia. The condition results from mutations in the FGFR3 gene, which affects how cartilage develops. These mutations can sometimes be inherited, but about 80% of babies with achondroplasia have normal-height parents. Random, new gene mutations at conception cause these cases.

What are the long-term outcomes for achondroplasia?

People with achondroplasia have about the same life expectancy and intellectual ability as the general population. The average height for men with the condition is 4’3” and for women is 4’1”.

Complications that can develop later in a child’s life include:

• Frequent ear infections
• Reduced muscle tone
• Narrowed spinal column (spinal stenosis)
• Restrictive lung disease due to a small upper airway and small ribcage
• Compression of the foramen magnum, the opening in the skull base where the spinal cord goes through
• Buildup of fluid in the brain (hydrocephalus)