National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Pseudoachondroplasia


Other Names:
Pseudoachondroplastic dysplasia; PSACH; Pseudoachondroplastic spondyloepiphyseal dysplasia; Pseudoachondroplastic dysplasia; PSACH; Pseudoachondroplastic spondyloepiphyseal dysplasia; Pseudoachondroplastic spondyloepiphyseal dysplasia syndrome; Spondyloepiphyseal dysplasia, pseudoachondroplastic See More
Categories:
Pseudoachondroplasia is an inherited disorder of bone growth which is characterized by short stature. Other features include short arms and legs, a waddling walk, early-onset joint pain (osteoarthritis), and a limited range of motion at the elbows and hips. Intelligence, facial features and head size are normal. Pseudoachondroplasia is caused by mutations in the COMP gene. This condition is inherited in an autosomal dominant pattern.[1]
Last updated: 1/19/2011

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Abnormality of epiphysis morphology
Abnormal shape of end part of bone
0005930
Abnormality of the hip bone
Abnormality of the hips
0003272
Abnormality of the metaphysis
Abnormality of the wide portion of a long bone
0000944
Delayed skeletal maturation
Delayed bone maturation
Delayed skeletal development
[ more ] 		0002750
Disproportionate short-limb short stature
Short limb dwarfism, disproportionate
Short-limbed dwarfism
[ more ] 		0008873
Irregular carpal bones 0004236
Micromelia
Smaller or shorter than typical limbs
0002983
Short metacarpal
Shortened long bone of hand
0010049
Short palm 0004279
30%-79% of people have these symptoms
Arthralgia
Joint pain
0002829
Gait disturbance
Abnormal gait
Abnormal walk
Impaired gait
[ more ] 		0001288
Hamartomatous polyposis 0004390
Hyperlordosis
Prominent swayback
0003307
Intestinal polyposis 0200008
Joint hyperflexibility
Joints move beyond expected range of motion
0005692
Osteoarthritis
Degenerative joint disease
0002758
Platyspondyly
Flattened vertebrae
0000926
Scoliosis 0002650
Short foot
Short feet
Small feet
[ more ] 		0001773
5%-29% of people have these symptoms
Genu valgum
Knock knees
0002857
Genu varum
Outward bowing at knees
Outward bow-leggedness
[ more ] 		0002970
Hypoplasia of the odontoid process 0003311
Kyphosis
Hunched back
Round back
[ more ] 		0002808
1%-4% of people have these symptoms
Beaking of vertebral bodies 0004568
Brachydactyly
Short fingers or toes
0001156
Irregular epiphyses
Irregular end part of long bone
0010582
Limited elbow extension
Decreased elbow extension
Elbow limited extension
Limitation of elbow extension
Limited extension at elbows
Limited forearm extension
Restricted elbow extension
[ more ] 		0001377
Limited shoulder movement 0006467
Percent of people who have these symptoms is not available through HPO
Atlantoaxial dislocation 0003414
Autosomal dominant inheritance 0000006
Carpal bone hypoplasia
Small carpal bones
Small carpals
[ more ] 		0001498
Cervical cord compression 0002341
Childhood onset short-limb short stature 0011405
Delayed epiphyseal ossification 0002663
Flared femoral metaphysis 0002834
Fragmented epiphyses
Fragmented end part of bone
0100168
Fragmented, irregular epiphyses
Fragmented, irregular end part of bone
0005063
Genu recurvatum
Back knee
Knee hyperextension
[ more ] 		0002816
Joint laxity
Joint instability
Lax joints
Loose-jointedness
Loosejointedness
[ more ] 		0001388
Limited hip extension
Restricted hip extension
0003093
Lumbar hyperlordosis
Excessive inward curvature of lower spine
0002938
Radial metaphyseal irregularity 0004019
Sensory neuropathy
Damage to nerves that sense feeling
0000763
Short distal phalanx of finger
Short outermost finger bone
0009882
Short long bone
Long bone shortening
0003026
Small epiphyses of the phalanges of the hand
Small end part of finger bones
0010236
Spatulate ribs 0012307
Ulnar deviation of the hand 0009487
Ulnar deviation of the wrist 0003049
Ulnar metaphyseal irregularity 0004042
Waddling gait
'Waddling' gait
Waddling walk
[ more ] 		0002515
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Last updated: 7/1/2020

All individuals with pseudoachondroplasia have short stature. While affected individuals are typically of normal length at birth, their growth rate tends to fall below the standard growth curve by age two. The average height of an adult male is 3 feet, 11 inches and the average height of an adult female is 3 feet, 9 inches. Other features of pseudoachondroplasia include short arms and legs, a waddling walk, early-onset joint pain (osteoarthritis), and a limited range of motion at the elbows and hips. Some individuals develop abnormal curvatures of the spine (scoliosis and/or lordosis) during childhood. People with pseudoachondroplasia have normal facial features, head size, and intelligence.[1]
Last updated: 1/19/2011
Pseudoachondroplasia is inherited in an autosomal dominant pattern, which means having one altered copy of the COMP gene in each cell is enough to cause the disorder. In some cases, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family.[1]
Last updated: 10/30/2012

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
Among people with pseudoachondroplasia, the average height of an adult male is 3 feet, 11 inches and the average height of an adult female is 3 feet, 9 inches. Some individuals develop abnormal curvatures of the spine (scoliosis and/or lordosis) during childhood that can persist into adulthood.[1]

People with achondroplasia often develop joint pain early in life, particularly in the hips or knees. The joints deteriorate over time, and about half of people with pseudoachondroplasia will need a joint replacement surgery during adulthood. Because of the effect this condition has on the joints, it is recommended that people with pseudoachondroplasia avoid activities that place a lot of stress and strain on the joints.[2]

To find out more about the outlook for people with pseudoachondroplasia, we recommend that you contact Little People of America.
Last updated: 10/30/2012

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
The principle differential diagnosis is achondroplasia (see this term), but the craniofacial anomalies present in this disorder are absent in patients with pseudoachondroplasia and radiographic findings differ significantly. Forms of multiple epiphyseal dysplasia (see these terms) may also be included in the differential diagnosis.
Visit the Orphanet disease page for more information.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • The U.S. National Institutes of Health, through the National Library of Medicine, developed ClinicalTrials.gov to provide patients, family members, and members of the public with current information on clinical research studies. There is a study titled Evaluation and Treatment of Skeletal Diseases which may be of interest to you.
  • The Research Portfolio Online Reporting Tool (RePORT) provides access to reports, data, and analyses of research activities at the National Institutes of Health (NIH), including information on NIH expenditures and the results of NIH-supported research. Although these projects may not conduct studies on humans, you may want to contact the investigators to learn more. To search for studies, enter the disease name in the "Text Search" box. Then click "Submit Query".

Patient Registry

  • A registry supports research by collecting of information about patients that share something in common, such as being diagnosed with Pseudoachondroplasia. The type of data collected can vary from registry to registry and is based on the goals and purpose of that registry. Some registries collect contact information while others collect more detailed medical information. Learn more about registries.

    Registries for Pseudoachondroplasia:
    International Skeletal Dysplasia Registry (ISDR)
     

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • Genetics Home Reference (GHR) contains information on Pseudoachondroplasia. This website is maintained by the National Library of Medicine.
  • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

In-Depth Information

  • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Pseudoachondroplasia. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • Our grandson was diagnosed recently with this disease and I am wondering if you could send me information on it. As his grandmother, I would like to know what are the health risks down the road for him and how we can help him live with this disease.  See answer

  • How do people inherit pseudoachondroplasia? See answer


  1. Pseudoachondroplasia. Genetics Home Reference (GHR). February 2008; http://ghr.nlm.nih.gov/condition=pseudoachondroplasia. Accessed 10/30/2012.
  2. Cohn DH. Pseudoachondroplasia. GeneReviews. April 13, 2010; http://www.ncbi.nlm.nih.gov/books/NBK1487/. Accessed 10/30/2012.