Skeletal malformations of Meox1-deficient zebrafish resemble human Klippel-Feil syndrome

Klippel-Feil syndrome is a congenital vertebral anomaly, which is characterised by the fusion of at least two cervical vertebrae and a clinically broad set of symptoms, including congenital scoliosis and elevated scapula (Sprengel's deformity). Klippel-Feil syndrome is associated with mutations in MEOX1. The zebrafish mutant choker (cho) carries a mutation in its orthologue, meox1. Although zebrafish is being increasingly employed as fidelitous models of human spinal disease, the vertebral column of Meox1-deficient fish has not been assessed for defects. Here, we describe the skeletal defects of meox1(cho) mutant zebrafish utilising alizarin red to stain bones and chemical maceration of soft tissue to detect fusions in an unbiased manner. Obtained data reveal that meox1(cho) mutants feature aspects of a number of described symptoms of patients who suffer from Klippel-Feil syndrome and have mutations in MEOX1. These include vertebral fusion, congenital scoliosis and an asymmetry of the pectoral girdle, which resembles Sprengel's deformity. Thus, the meox1(cho) mutant zebrafish may serve as a useful tool to study the pathogenesis of the symptoms associated with Klippel-Feil syndrome.