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

Hypochondroplasia

Hypochondroplasia is a form of skeletal disease characterized by very short stature. Hypochondroplasia is similar to achondroplasia, but the features tend to be milder. People with hypochondroplasia usually have very short stature, large head, accentuated lordosis, short arms and legs, and broad, short hands and feet. Other features include a limited range of motion in the elbows, lordosis, and bowed legs. Uncommon symptoms may include learning difficulties and convulsions.[1][2] Hypochondroplasia is caused by mutations in the FGFR3 gene and is inherited in an autosomal dominant fashion.[1] Treatment is symptomatic and may include surgery (laminectomy and decompression) to treat lumbar (low back) spinal stenosis (nerve compression caused by the the spine defects), physical therapy, and medication. Trials of growth hormone treatment in hypochondroplasia have shown good results in a few cases.[2]
Last updated: 1/11/2018

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
Abnormal form of the vertebral bodies 0003312
Brachydactyly
Short fingers or toes
0001156
Childhood onset short-limb short stature 0011405
Micromelia
Smaller or shorter than typical limbs
0002983
Short toe
Short toes
Stubby toes
[ more ] 		0001831
Skeletal dysplasia 0002652
30%-79% of people have these symptoms
Abnormality of femur morphology
Abnormality of the thighbone
0002823
Abnormality of pelvic girdle bone morphology
Abnormal shape of pelvic girdle bone
0002644
Abnormality of the elbow
Abnormality of the elbows
0009811
Abnormality of the metaphysis
Abnormality of the wide portion of a long bone
0000944
Genu varum
Outward bow-leggedness
Outward bowing at knees
[ more ] 		0002970
Joint hyperflexibility
Joints move beyond expected range of motion
0005692
5%-29% of people have these symptoms
Acanthosis nigricans
Darkened and thickened skin
0000956
Hyperlordosis
Prominent swayback
0003307
Intellectual disability
Mental deficiency
Mental retardation
Mental-retardation
Mental retardation, nonspecific
[ more ] 		0001249
Macrocephaly
Increased size of skull
Large head
Large head circumference
[ more ] 		0000256
Osteoarthritis
Degenerative joint disease
0002758
Scoliosis 0002650
Sleep apnea
Pauses in breathing while sleeping
0010535
Spinal canal stenosis
Narrow spinal canal
0003416
Percent of people who have these symptoms is not available through HPO
Aplasia/hypoplasia of the extremities
Absent/small extremities
Absent/underdeveloped extremities
[ more ] 		0009815
Autosomal dominant inheritance 0000006
Flared metaphysis
Flared wide portion of long bone
0003015
Frontal bossing 0002007
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
Lumbar hyperlordosis
Excessive inward curvature of lower spine
0002938
Malar flattening
Zygomatic flattening
0000272
Short long bone
Long bone shortening
0003026
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Last updated: 7/1/2020

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.
Treatment depends on the symptoms seen in each child. In some cases, stature is almost normal when compared with the stature of other family members. When necessary, treatment may include:[2]
  • Developmental intervention and special education for learning disabilities
  • A surgery called laminectomy or a procedure known as decompression which can take pressure off the spinal nerves or spinal canal in cases of spinal stenosis (narrowing of the spine)
  • Growth hormone therapy at around the time of puberty (this has shown mixed results)
Support groups can help individuals with hypochondroplasia and their family members adapt to short stature through peer support. They can also offer information on employment, education, disability rights, adoption of children of short stature, medical issues, suitable clothing, adaptive devices, and parenting through local meetings, workshops and seminars.[2] Please see the contact information for support groups for hypochondroplasia.

Sometimes, children with hypochondroplasia are more severely affected, and have very similar features to those of achondroplasia. In these cases, recommendations for the management of achondroplasia (outlined by the American Academy of Pediatrics Committee on Genetics) may be considered. See also a description of the management of achondroplasia.[2]

A consultation with a genetic doctor for genetic counseling is also recommended so that there can be discussion of issues such as risk of recurrence and parental concerns related to short stature.

Last updated: 1/11/2018

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
Hypochondroplasia closely resembles achondroplasia (also caused by mutations in the FGFR3 gene; see this term), although the short stature and skeletal disproportion are clearly less pronounced in hypochondroplasia and the two conditions can be differentiated on the basis of the milder radiological findings in hypochondroplasia.
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

  • ClinicalTrials.gov lists trials that are related to Hypochondroplasia. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.
  • 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.

Patient Registry

  • A registry supports research by collecting of information about patients that share something in common, such as being diagnosed with Hypochondroplasia. 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 Hypochondroplasia:
    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

Organizations Providing General Support

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 Hypochondroplasia. 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.
  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • 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 Hypochondroplasia. 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

  • Are there any associated problems with mucosal tissue (frequent, severe nosebleeds) with this disorder. Would later closure of fontanelle (after 18 months) be associated with this syndrome? Are cognitive or speech-language symptoms associated with the syndrome? See answer

  • What is the treatment? Is there a way to improve the bone growth? See answer


  1. Hypochondroplasia. Genetics Home Reference. 2012; http://ghr.nlm.nih.gov/condition/hypochondroplasia.
  2. Bober MB, Bellus GA, Nikkel SM & Tiller GE. Hypochondroplasia. GeneReviews. 2013; http://www.ncbi.nlm.nih.gov/books/NBK1477/.