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Extremely short stature as a result of acromesomelic
dysplasia of the limbs (forearms, forelegs, hands, feet). In general,
patients present with normal intelligence. Joint dislocations may occur.
Normal craniofacial and axial skeleton. Care with positioning.
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Acromesomelic Dwarfism; AMD.
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Type I = Maroteaux (AMDM) type
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Type II = Hunter-Thompson (AMDH) type
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Type III = Chondrodysplasia Grebe Type
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Type IV = Brahimi Bacha type or Algerian type
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Type V = Campailla Martinelli type or Italian type
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Autosomal recessive. The AMDM gene has not yet
been identified, but a mutation at the location 9p13-q12 appears to be the
most likely cause. In 1996 the AMDH gene was identified as a mutation in
cartilage-derived morphogenetic protein 1 (CDMP-1), which has been mapped to
20q11.2.
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The genetic mutation leads to abnormal linear
growth of the skeleton.
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Characteristic clinical and radiographic features in
infancy.
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Type I: Maroteaux Type (Amdm)
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Skeletal disorder that affects the
limbs and the spine. Newborns affected with AMDM generally are of normal
weight, length, and head circumference but can have short-appearing limbs.
Older children and adults are significantly shorter than their peers,
generally of normal intelligence, and are not expected to have any
additional medical complications other than their skeletal changes.
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Type II: Hunter-Thompson Type (Amdh)
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The prevalence is unknown but
it seems to be less frequent than the other types of acromesomelic
dysplasia. Dwarfism is present at birth. The adult height is approximately
120 cm. The trunk is normally proportioned. Severe dwarfism is mostly
limited to the limbs (extremely short stature), with the legs more severely
affected than the arms. The middle segment (forearm with bowing of the
radius and posterior dislocation of its head; lower leg with marked
shortening of tibia and fibula) and distal segment (short hands and feet)
show the most severe changes. Dislocation of the large joints (elbow, hip,
knee, ankle) is frequently observed. The fingers usually are very short
secondary to cuboidal shape of the metacarpals and shortening of the middle
and proximal phalanges. Intelligence, facial appearance, and head
circumference are normal. Corneal opacities may occur.
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Type III: Grebe Type (Amdg)
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Short-limbed dwarfism affecting both
sexes and evident from birth. The most characteristic features are extremely
short limbs, with the legs more severely affected than the upper limbs. The
hands are extremely short with toe-like fingers, and the feet are in valgus
position. Polydactyly is present in 50% of patients. Facies is normal and
obesity is common. Mental development is delayed, but patients ultimately
are mentally normal.
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Type IV: Brahimi Bacha Type
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Spondylometaphyseal dysplasia, most
often associated with severe metaphyseal changes and severe genua valgum.
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Type V: Campailla Martinelli Type
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Dwarfism with severe limb
shortening, most pronounced in the ...