A rare form of autosomal recessive osteochondrodysplasia characterized by severe dwarfism with marked hypomelia and deformation.
Grebe Chondrodysplasia; Brazilian Achondrogenesis; Acromesomelic Dysplasia, Grebe Type; Acromesomelic Dwarfism; Achondrogenesis Type II.
Less than 100 cases have been described. An increased frequency has been reported from Bahia, Brazil, where the gene frequency was evaluated to be 1:50, with a prevalence of 1:2,000 live births.
Autosomal recessive as a result of mutations in the GDF5 (Growth/Differentiation Factor 5) gene located on chromosome 20q11.2. GDF5 is also known as CDMP1 (cartilage-derived morphogenetic protein1), BMP14 (Bone Morphogenetic Protein 14), LAP4 (Lipopolysaccharide-Associated Protein 4), or LPS-Associated Protein 4.
Based on the clinical findings of severe dwarfism with marked hypomelia and deformation of upper and lower limbs, with a proximo-to-distally increasing gradient of severity. Radiographs show shortening and deformation of the forearm and foreleg bones, fusion of carpal and tarsal bones, and absence of proximal and middle phalanges and several metacarpal and metatarsal bones.
This disorder is limited to the skeleton and results in disproportionate shortening of the appendicular skeleton, mainly involving the forearms/forelegs and hands/feet. The arms are less severely affected than the legs and the abnormalities are more severe distally: the humeri and femora are short but normally shaped, whereas radius/ulna and tibia/fibula are short and deformed. The carpal and tarsal bones and phalanges are rudimentary, and the metacarpals, metatarsals, and patellae are hypoplastic or absent. The digits are consequently very short with a globular appearance connected with a soft-tissue bridge. Postaxial polydactyly and valgus deformity of hand and foot are common. The metatarsal, talus, cuneiform, and navicular bones may be fused. The axial skeleton is normal. An increased frequency of stillbirth and neonatal death has been reported. The patients are intellectually normal.
Precautions before anesthesia
Routine preoperative assessment is considered adequate. Check joint mobility for optimal intraoperative positioning.
The features of the disease suggest that peripheral vascular access may be difficult. Careful intraoperative positioning and padding are required to prevent pressure sores and nerve injury. Regional anesthesia is not contraindicated, but is probably difficult to perform due to positioning problems. Ultrasound guidance will most likely be helpful.
None specific to this condition.
Other conditions to be considered
☞Acromesomelic Dysplasia: Refer to this medical condition for a complete overview of the different types.
☞Acromesomelic Dysplasia Type I (Maroteaux Type): Very rare, autosomal recessive inherited disorder that seems to have its highest prevalence on the South Atlantic island of St. Helena (to which Napoleon was exiled in 1815). Dwarfism is severe ...