Clinical and molecular analysis of Grebe acromesomelic dysplasia in an Omani family

Grebe syndrome is a rare autosomal recessive acromesomelic dysplasia. The syndrome was studied clinically, radiographically, and genetically in an Omani family with four affected children. The affected persons had normal axial skeletons, severely shortened, and deformed limbs with severity increasing in a proximo-distal gradient, and subluxated joints. The humeri and femora were hypoplastic with distal malformations. The radii/ulnae were shortened and deformed whereas carpal bones were invariably rudimentary or absent. The tibiae appeared rudimentary; fibulae were absent in two children, and some tarsal and metatarsal bones were absent. The proximal and middle phalanges were absent while the distal phalanges were present. The father and mother had short first metacarpal and middle phalynx of the fifth finger and hallux valgus respectively. Transition A1137G and deletion delG1144 mutations in the gene encoding the cartilage-derived morphogenetic protein-1 (CDMP-1) were identified in this family. The A1137G is a silent mutation coding for lysine, whereas the delG1144 predicts a frameshift mutation resulting in a presumable loss of the CDMP-1 biologically active carboxy-terminal domain. The affected siblings were homozygous for the delG1144 mutation while parents were heterozygous.