CCDC126 is a 140 amino acid secreted protein encoded by a gene mapping to human chromosome 7. Chromosome 7 is about 158 milllion bases long，encodes over 1000 genes and makes up about 5% of the human genome. Chromosome 7 has been linked to Osteogenesis imperfecta，Pendred syndrome，Lissencephaly，Citrullinemia and Shwachman-Diamond syndrome. The deletion of a portion of the q arm of chromosome 7 is associated with Williams-Beuren syndrome，a condition characterized by mild mental retardation，an unusual comfort and friendliness with strangers and an elfin appearance. Deletions of portions of the q arm of chromosome 7 are also seen in a number of myeloid disorders including cases of acute myelogenous leukemia and myelodysplasia.