Achondroplasia

What is achondroplasia?

In the early stages of development, much of the fetal skeleton is made up of cartilage tissue, which turns into bone. Achondroplasia occurs when cartilage tissue doesn't develop in the bones of your arms and legs. This genetic disorder leads to short-limb dwarfism with the upper parts of arms and legs shorter than the lower portions of those limbs (rhizomelic shortening).

What is the difference between achondroplasia and skeletal dysplasia (dwarfism)?

Achondroplasia is the most common form of skeletal dysplasia, which is the umbrella term used to identify hundreds of conditions that affect the growth of bones and cartilage. Achondroplasia specifically targets bone growth in your arms and legs.

Is achondroplasia hereditary?

• Most cases of achondroplasia are not inherited. Anyone can be affected by achondroplasia. Around 80% of individuals with achondroplasia have parents of normal height and are born with a new gene alteration (de novo mutation). It is rare that these parents will have another child with achondroplasia.
• Only one parent needs to pass down the gene for a child to be born with achondroplasia (autosomal dominant). There is a 50% chance of a person with achondroplasia and a partner who does not have achondroplasia having a child with the disorder.
• If both parents have achondroplasia, there is a 25% chance that the child will be born with homozygous achondroplasia, which leads to stillbirth or death shortly after birth.

How many people are affected with achondroplasia?

About 1 in 15,000 to 1 in 40,000 individuals are born with achondroplasia.

How does achondroplasia affect my child’s body?

Infants born with achondroplasia normally have weak muscle tone (hypotonia), which could delay motor skill development. There’s is also a high risk of spinal cord compression and upper respiratory blockages among infants, which increases the risk of health complications.

It is common for people with achondroplasia to have breathing problems, recurrent ear infections and be prone to obesity.

All children with achondroplasia should be carefully monitored regularly by a healthcare provider to treat or prevent any symptoms that may arise.

What causes achondroplasia?

Achondroplasia is caused by a gene mutation in the receptor that converts cartilage to bone during fetal development.

What are the symptoms of achondroplasia?

• Bones are shortened (thigh, upper arm).
• Short hands and feet.
• Large separation between third and fourth fingers.
• Maximum height of 4-ft.
• Head larger than normal.
• Prominent forehead.
• Flat nose.
• Delayed development in infants (sitting, crawling, walking).

What are the long-term effects of achondroplasia on your body?

• Back and leg pain.
• Breathing problems (apnea).
• Obesity.
• Recurring ear infections.
• Curved spine.
• Bowed legs.
• Excess fluid on your brain (hydrocephalus).
• Obstructive sleep apnea.

How early can achondroplasia be diagnosed?

Doctors can use ultrasounds to detect achondroplasia before birth if your baby’s arms and legs appear shorter than average and if their head is large. Most cases of achondroplasia aren't confirmed until after birth.

How is achondroplasia diagnosed?

• X-ray.
• Physical examination.
• Prenatal examination (if one or both parents are affected).
• Genetic testing (FGFR3 gene).
• MRI or CT scan to identify muscle weakness or spinal cord compression.

How is achondroplasia treated?

There is no specific treatment for achondroplasia other than managing symptoms. Monitoring height, weight and head circumference is recommended during early diagnosis in infants to track growth progress.

Is there a cure for achondroplasia?

No, there's no cure for achondroplasia, but almost everyone who's diagnosed is able to live a full and healthy life.

How do I manage symptoms of achondroplasia?

Management of achondroplasia is focused on taking care of potential complications, which may include:

• Weight management and encouraging healthy eating habits to prevent obesity.
• Surgery (ventriculoperitoneal shunt) to decrease fluid pressure on your brain or to correct a life-threatening complication called craniocervical junction compression.
• Surgery to remove adenoids and tonsils.
• Growth hormones.
• Use of continuous positive airway pressure (CPAP) nasal mask for apnea.
• Ear tubes or antibiotics to prevent ear infections.
• Support for socialization.
• Much research is being done on medications that might help increase height by a few inches.

How can I reduce my risk of having a child with achondroplasia?

Since achondroplasia is a rare genetic condition that's often the result of a new gene mutation, there's no way to prevent those random cases. If a parent has achondroplasia, the chance to pass it on could be significantly decreased through preimplantation genetic testing. If you’re interested in learning more, please should speak with your OB/GYN provider.

What is the life expectancy for someone with achondroplasia?

The majority of people living with achondroplasia have a normal life span and normal intelligence, regardless of delayed development in infancy. Though complications from achondroplasia are a possibility, taking care of symptoms can help prevent serious health problems from occurring later in life.

How can I help my child with achondroplasia?

Children diagnosed with achondroplasia can lead healthy and full lives. After treating your child’s medical needs, focus on providing a welcoming environment for your child to thrive by:

• Eliminating physical challenges to promote independence (use of a step stool, extending light switches).
• Providing emotional and educational support (to prevent bullying in school).
• Engaging with groups and organizations in the dwarfism community.

When should I contact my healthcare provider?

Staying regular with checkups during infancy and throughout childhood can prevent many symptoms of achondroplasia from occurring.

Contact your healthcare provider during early infancy if your child isn’t meeting height benchmarks for their age or you’re seeing developmental delays in physical goals, like sitting, crawling and walking.

If your child’s having problems breathing, frequently gets ear infections, having back and leg pain or is at risk of obesity, seek treatment from a healthcare professional.

A note from Cleveland Clinic

Though health complications may occur during childhood, the diagnosis of achondroplasia won’t hinder your child’s ability to live a happy and healthy life. Having a positive outlook can make a difference in your child’s self-esteem, especially by being inclusive and caring for your child according to their age, not their size.