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Disease Profile

Hypochondroplasia

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.
1-9 / 100 000

3,310 - 29,790

US Estimated

1-9 / 100 000

5,135 - 46,215

Europe Estimated

Age of onset

Childhood

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ICD-10

Q77.4

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

HCH

Categories

Congenital and Genetic Diseases; Musculoskeletal Diseases

Summary

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]

Symptoms

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.

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, nonspecific
Mental-retardation

[ 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

Diagnosis

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

    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.

    Organizations

    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

        Learn more

        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.

            References

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

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