Spondyloepimetaphyseal dysplasia, Aggrecan type

Alternate names

SEMD, Aggrecan type

Definition

Spondyloepimetaphyseal dysplasia, aggrecan type is a new form of skeletal dysplasia characterized by severe short stature, facial dysmorphism and characteristic radiographic findings.

Epidemiology

To date, three cases have been described, all originating from the same family.

Cause

The disease results from a missense mutation affecting the C-type lectin domain of aggrecan (AGC1 gene; chromosome 15) which regulates endochondral ossification.

Inheritance

[[File:Autorecessive.svg|thumb|right|Autosomal recessive inheritance, a 25% chance] Transmission is autosomal-recessive.

Signs and symptoms

• Facial features include midface hypoplasia with almost absent nasal cartilage, and relative prognathism and macrocephaly.
• Radiographic findings include irregular epiphyses of long bones with widened metaphyses, platyspondyly, multiple cervical-vertebral clefts and brachydactyly.

Clinical presentation

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms

• Abnormality of the nail
• Absent nasal bridge(Missing nasal bridge)
• Barrel-shaped chest(Barrel chest)
• Brachydactyly(Short fingers or toes)
• Broad thumb(Broad thumbs)
• Joint laxity(Joint instability)
• Low-set, posteriorly rotated ears
• Lumbar hyperlordosis(Excessive inward curvature of lower spine)
• Mandibular prognathia(Big lower jaw)
• Mesomelia(Disproportionately short middle portion of limb)
• Midface retrusion(Decreased size of midface)
• Relative macrocephaly(Relatively large head)
• Rhizomelia(Disproportionately short upper portion of limb)
• Short neck(Decreased length of neck)

30%-79% of people have these symptoms

• Functional respiratory abnormality
• Hoarse voice(Hoarseness)

1%-4% of people have these symptoms

• Malar flattening(Zygomatic flattening)
• Short finger(Stubby finger)

NIH genetic and rare disease info

• NIH info on Spondyloepimetaphyseal dysplasia, Aggrecan type

Spondyloepimetaphyseal dysplasia, Aggrecan type is a rare disease.

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