Deletion of the WWOX gene and frequent loss of its protein expression in human osteosarcoma. To evaluate the role of WWOX gene in human osteosarcoma, array comparative genomic hybridization on 10 frozen osteosarcoma specimens and immunohistochemical staining of 55 formalin-fixed and paraffin-embedded tissues for WWOX was performed. Deletion of the WWOX gene was observed in 3 of 10 samples and the WWOX protein was undetectable in 34 of 55 osteosarcomas. This is the first investigation of the role of WWOX gene in human osteosarcoma. The WWOX gene deletion, loss of its protein expression, and lack of correlation of WWOX expression with patient survival suggest loss of WWOX expression is an early event in the pathogenesis of osteosarcoma and the phenotypic results of its deletion do not imminently result in patient death.2009. Published by Elsevier Ireland Ltd.