Pseudoachondroplasia

What is pseudoachondroplasia?

Pseudoachondroplasia is a type of skeletal dysplasia in which bone growth slows down between 1 and 2 years old, causing short stature and short-limbed dwarfism. This condition doesn’t affect intellectual development or lifespan.

What causes pseudoachondroplasia?

A change in the cartilage oligomeric matrix protein (COMP) gene, which affects how cartilage and bones grow, causes pseudoachondroplasia. As a result, the bones are shorter and shaped differently from typical bones.

Who gets pseudoachondroplasia?

Children can inherit pseudoachondroplasia from either parent if they also have the condition, but most children have a new or spontaneous genetic change, meaning neither parent passed on the genetic change. Pseudoachondroplasia affects around 1 out of every 30,000 babies. 

What’s the difference between pseudoachondroplasia and achondroplasia?

Pseudoachondroplasia and achondroplasia are both forms of short-limbed dwarfism but are caused by changes in different genes, leading to different kinds of changes in the bones. For example, joint pain and early-onset arthritis are seen in pseudoachondroplasia but not achondroplasia. Bone differences are usually clear at birth for achondroplasia but do not develop until around 2 years old with pseudoachnodroplasia.

What’s the life expectancy for pseudoachondroplasia?

Children with pseudoachondroplasia have normal life expectancy and lead full and productive lives.

What are the signs and symptoms of pseudoachondroplasia?

As a child grows, signs of pseudoachondroplasia become more noticeable. Along with short stature, symptoms include:

• Neck instability that can compress the spinal cord
• Arms and legs that are short compared with the body
• Short, wide fingers
• A waddling walk caused by differences in the hips
• Unusually flexible joints except for the elbows
• A curved spine
• Bowed legs with knees bending outwards
• Arthritis and joint pain

When should I reach out to my child’s care team?

It’s important to seek care if you see the following:

• A loss of motor skills like stopping crawling or losing bladder or bowel control
• Your child complains of pain, tingling, numbness or weakness in their arms or legs
• You notice pauses in breathing or loud constant snoring while asleep

How do we diagnose pseudoachondroplasia?

Providers don’t usually recognize pseudoachondroplasia at birth unless there’s a family history. At around one to two years old, most children with the condition fall behind the typical growth curve for height. We typically make a diagnosis between the ages of one and four years old.

Our specialists in the Skeletal Dysplasia Program conduct a physical exam and look at X-rays to diagnose pseudoachondroplasia. We also offer genetic counseling services and perform genetic testing to identify the condition at a genetic level.

How do we treat pseudoachondroplasia?

While there isn’t a cure for pseudoachondroplasia, many treatments can help with symptoms, including:

• A sleep study may find sleep apnea that we can treat with tonsil removal surgery or a continuous positive airway pressure (CPAP) device
• Monitoring of bow-legs or knock-knees that may lead to surgery
• Choosing activities that preserve the joints (like swimming) over those that put pressure on them (like trampolines)
• Taking over-the-counter medication and hot baths to help with joint pain
• Physical and occupational therapy to improve strength and help perform daily activities  
• Spinal surgery for curvature or compression
• Nutritional and lifestyle consultations

Why choose Children’s Colorado for pseudoachondroplasia treatment?

As the first pediatric skeletal dysplasia program in the Rocky Mountain region, we have the most experienced and inclusive experts to care for children with these rare conditions. Our approach to multidisciplinary care means your child can see all their specialists in one place, at one time, to ensure comprehensive care. As a Rare Disease Center of Excellence, we have all the specialists and experience to treat rare diseases at the highest level.

We also extend our care outside our hospital to our local and national communities to bring families with skeletal dysplasia together. We collaborate with many groups such as Little People of America to further support research, education and awareness of rare skeletal dysplasia conditions.

Helpful resources

Parent Toolkit: Managing Your Child's Medical Illness at School

Little People of America

Dwarf Athletic Association of America

Courageous Parents Network

Parent-to-Parent

Family Voices

Make-A-Wish Foundation