How is achondrogenesis type II inherited?

achondrogenesis type II follows an autosomal dominant inheritance pattern. This means inheriting just one copy of the altered gene from either parent can cause the condition.

How rare is achondrogenesis type II?

achondrogenesis type II is classified as not well established. The estimated prevalence is approximately Unknown. Because rare disease data can be limited, actual numbers may differ from published estimates.

How is achondrogenesis type II diagnosed?

Information about diagnosis is currently limited for this condition.

Are there treatments for achondrogenesis type II?

Information about treatment is currently limited for this condition.

What are the specific complications associated with achondrogenesis type II?

Achondrogenesis type II can lead to serious complications due to underdeveloped bones and lungs. The severe micromelia and small thorax can make it difficult for individuals to breathe properly. This can result in respiratory issues that are life-threatening, making medical care essential for those affected.

How does achondrogenesis type II affect daily life for individuals and their families?

Daily life for individuals with achondrogenesis type II can be very challenging due to their physical limitations. The short limbs and small chest can impact mobility and basic activities. Families may need to provide significant support and care, which can be emotionally and physically demanding.

What is the prognosis for someone diagnosed with achondrogenesis type II?

The prognosis for achondrogenesis type II is considered very serious, as it is classified as a lethal condition. The severe skeletal and lung abnormalities significantly affect life expectancy. Unfortunately, detailed information about long-term outcomes is limited, but the condition poses major health risks.

What should families consider when planning for a child with achondrogenesis type II?

Families planning for a child with achondrogenesis type II should be aware of the serious health challenges associated with this condition. It's important to discuss potential outcomes and care needs with healthcare professionals. Genetic counseling may also be beneficial to understand the risks and implications for future pregnancies.

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achondrogenesis type II - Clinical Profile, Genes & Research | Kisho | Kisho

Features include always present findings: Long philtrum, Abnormally large globe, Short long bone, and Delayed tibial epiphyseal ossification and others. 25 total HPO annotations.

Organ System	Phenotype Count	Example Features
Bones and joints	6	Crescent-shaped iliac bone, Short tubular bones of the hand, Short long bone
Arms and legs	3	Disproportionate short-limb short stature, Short tubular bones of the hand, Abnormal foot morphology
Growth and development	2	Disproportionate short-limb short stature, Disproportionate short-trunk short stature
Pregnancy and birth	1	Hydrops fetalis
Kidneys and urinary system	1	Short tubular bones of the hand
Head and neck	1	Cleft palate

GeneReviews

Clinical Guidance

Spondylometaphyseal dysplasia, corner fracture type (SMDCF) is characterized by short stature and a waddling gait in early childhood. Short stature may be present at birth or develop in early infancy. Individuals may present with short limbs and/or short trunk. Complications include coxa vara, scoliosis, and chronic pain. Some individuals have ocular manifestations. To date, approximately 50 individuals with spondylometaphyseal dysplasia, corner fracture type (SMDCF) have been reported. A heterozygous COL2A1 or FN1 pathogenic variant has been identified in 23 individuals with SMDCF [, , , , , , ]. The following description of the phenotypic features associated with this condition is based on these reports. Two affected individuals had no detailed clinical description . Table 2. Spondylometaphyseal Dysplasia, Corner Fracture Type: Frequency of Select Features

Feature	Proportion of Persons w/Feature	Comment
Abnormal metaphyses	20/20	—

Diagnosis

Drawn from GeneReviews diagnostic guidelines, newborn screening panel status (RUSP), and ClinGen gene-disease validity classifications. Reflects current clinical evidence and consensus where available.

GeneReviews

Diagnostic Criteria

Formal diagnostic criteria for spondylometaphyseal dysplasia, corner fracture type (SMDCF) have not been established.

Suggestive Findings

SMDCF should be suspected in individuals with the following clinical and radiographic features and family history.

Clinical features

Mild-to-moderate short stature noted at birth in some individuals with short lower extremities and/or short trunk
Mild-to-severe scoliosis
Genu varum or valgum
Pectus carinatum
Limited mobility and/or musculoskeletal pain
Vision impairment (e.g., myopia, borderline increased intraocular pressure, Brown syndrome [strabismus caused by dysfunction of the superior oblique muscle])
Normal hearing
Normal intelligence

Radiographic features

Source: GeneReviews — "Spondylometaphyseal Dysplasia, Corner Fracture Type"

GeneReviews

Differential Diagnosis

Genetic disorders with overlapping clinical and radiographic features of spondylometaphyseal dysplasia, corner fracture type (SMDCF) include those listed in . Table 4. Genes of Interest in the Differential Diagnosis of Spondylometaphyseal Dysplasia, Corner Fracture Type

Gene	Disorder	MOI	Features of Disorder
ATP7A	Menkes disease (See ATP7A-Related Copper Transport Disorders.)	XL	Short stature
CFAP410	CFAP410-related axial spondylometaphyseal dysplasia (OMIM 602271)

Genetic testing for COL2A1 is available. Testing is considered confirmatory for diagnosis.

Treatment

Compiled from FDA-approved drug records, orphan drug designations, and FDA Adverse Event Reporting System (FAERS) safety data. GeneReviews management guidance is included where available.

No approved treatments are currently available for achondrogenesis type II. The disease remains an area of unmet medical need.

GeneReviews

Management Guidelines

No clinical practice guidelines for spondylometaphyseal dysplasia, corner fracture type (SMDCF) have been published. In the absence of published guidelines, the following recommendations are based on the authors' personal experience managing individuals with this disorder. Evaluations Following Initial Diagnosis To establish the extent of disease and needs in an individual diagnosed with SMDCF, the evaluations summarized (if not performed as part of the evaluation that led to the diagnosis) are recommended. Table 5. Spondylometaphyseal Dysplasia, Corner Fracture Type: Recommended Evaluations Following Initial Diagnosis

System	Evaluation	Comment
Musculoskeletal	Referral to orthopedic surgeon, physiatrist, PT depending on local practices	To evaluate for scoliosis, mobility issues, other skeletal manifestations; If atlantoaxial instability is present, eval by anesthesiologist pulmonary assessment (when indicated) prior to any surgery2
Ophthalmology	Referral to ophthalmologist for vision assessment	Incl eval of intraocular pressure in persons w/FN1-related SMDCF3
Cardiovascular	Eval of blood pressure	In persons w/FN1-related SMDCF3
Respiratory	Eval by pulmonologist	Recommended for those w/COL2A1-related SMDCF4
Genetic counseling	By genetics professionals5

Source: GeneReviews — "Spondylometaphyseal Dysplasia, Corner Fracture Type"

GeneReviews

Clinical Guidance

Avoid contact sports if atlantoaxial instability is present. For individuals with joint pain, avoid activities that strain joints; instead, favor joint-friendly activities (e.g., swimming, cycling).

Source: GeneReviews — "Spondylometaphyseal Dysplasia, Corner Fracture Type"

GeneReviews

Therapies Under Investigation

Search ClinicalTrials.gov in the US and EU Clinical Trials Register in Europe for access to information on clinical studies for a wide range of diseases and conditions. Note: There may not be clinical trials for this disorder.

Source: GeneReviews — "Spondylometaphyseal Dysplasia, Corner Fracture Type"

Clinical Trials

1 trial found

Explore Trials

Prognosis

Based on GeneReviews surveillance recommendations, HPO phenotype frequency and severity annotations, and published prevalence estimates from Orphanet and OMIM.

GeneReviews

Surveillance Guidelines

To monitor existing manifestations, the individual's response to supportive care, and the emergence of new manifestations, the evaluations summarized in are recommended. Table 7. Spondylometaphyseal Dysplasia, Corner Fracture Type: Recommended Surveillance

System/Concern	Evaluation	Frequency
Musculoskeletal	Eval by orthopedic surgeon physiatrist depending on local practices for scoliosis, other skeletal manifestations, mobility issues, chronic joint pain	Annually
Glaucoma	Eval of intraocular pressure1	Annually in those w/FN1-related SMDCF Hypertension
Psychosocial	Assessment for psychosocial issues	Annually 1. Recommendations are based on a single individual reported with this feature.

Source: GeneReviews — "Spondylometaphyseal Dysplasia, Corner Fracture Type"

Phenotype severity distribution: 8 always present features.

Estimated prevalence: Unknown (Unknown prevalence).

Medical References

External Resources

OMIM

Online Mendelian Inheritance in Man

OMIM:200610

Orphanet

European rare disease database

Orphanet:93296

GARD

Genetic and Rare Diseases Info Center

GARD:8713

Questions for Your Care Team

→Are any of the 1 active clinical trial a good fit for my situation?
→Should I pursue genetic testing for COL2A1, and what would the results mean for my family?
→Are there specialists or centers of excellence for this condition in my area?
→Is there a patient registry I should consider joining?

FAQ

Frequently Asked Questions

Common questions about achondrogenesis type II

Achondrogenesis type II (also known as achondrogenesis, Langer-Saldino type, or ACG2) is a very rare skeletal disorder that affects the development of the bones. It is part of a group of conditions related to type 2 collagen and manifests with severe changes in skeletal formation. The condition is recognized by a set of distinct physical features that affect the overall shape and growth of the body. In people with this condition, the bones are underdeveloped and the overall skeletal structure is severely affected. The disorder is known for its severe micromelia (shortened limbs), a short neck accompanied by a large head, a small chest, and a protuberant abdomen. Additional facial features may include a prominent forehead, a small chin, and in some cases, a cleft palate. These characteristics are related to the abnormal development of cartilage, which is an important precursor to bone formation.

People with achondrogenesis type II often exhibit several notable symptoms. These include very short limbs (micromelia), a short neck with a relatively large head, and a small thorax. Other features include a prominent forehead, a small chin, and sometimes a cleft palate. The chest may be small and the abdomen protuberant. The lungs in affected individuals are underdeveloped, which has important impacts on the body’s ability to breathe.

This condition is caused by changes in the COL2A1 gene, which plays a critical role in producing type 2 collagen. Type 2 collagen is essential for the normal development of cartilage and bone. Mutations in this gene lead to the abnormal formation of cartilage, which in turn affects bone growth, leading to the multiple skeletal abnormalities that are characteristic of achondrogenesis type II. Associated genes include COL2A1.

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achondrogenesis type II

Overview

Clinical Presentation

Clinical Guidance

Explore clinical features

Genetic Landscape

Clinical Guidance

Penetrance

Diagnosis

Diagnostic Criteria

Suggestive Findings

Differential Diagnosis

Treatment

Management Guidelines

Clinical Guidance

Therapies Under Investigation

Clinical Trials

Prognosis

Surveillance Guidelines

Research Landscape

Recent Publications

Medical References

External Resources

OMIM

Orphanet

GARD

Questions for Your Care Team

Questions for Your Care Team

FAQ

Frequently Asked Questions

achondrogenesis type II

Overview

Clinical Presentation

Clinical Guidance

Explore clinical features

Genetic Landscape

Clinical Guidance

Penetrance

Diagnosis

Diagnostic Criteria

Suggestive Findings

Differential Diagnosis

Treatment

Management Guidelines

Clinical Guidance

Therapies Under Investigation

Clinical Trials

Prognosis

Surveillance Guidelines

Research Landscape

Recent Publications

Medical References

External Resources

OMIM

Orphanet

GARD

Related Diseases

Questions for Your Care Team

Questions for Your Care Team

FAQ

Frequently Asked Questions

What is achondrogenesis type II?

What are the symptoms of achondrogenesis type II?

What causes achondrogenesis type II?

How is achondrogenesis type II inherited?

How rare is achondrogenesis type II?

How is achondrogenesis type II diagnosed?

Are there treatments for achondrogenesis type II?

What are the specific complications associated with achondrogenesis type II?

How does achondrogenesis type II affect daily life for individuals and their families?

What is the prognosis for someone diagnosed with achondrogenesis type II?

What should families consider when planning for a child with achondrogenesis type II?