GLCCI1, also known as TSSN1, GIG18 or FAM117C, is a 547 amino acid protein found in thymus and CD4(+)CD8(+) cells during specific stages of spermatogenesis in testis. Subject to phosphorylation, GLCCI1 is encoded by a gene located on human chromosome 7, which houses over 1,000 genes and comprises nearly 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.