CGI-99 is a 244 amino acid protein that localizes to the nucleus, as well as to the cytoplasm, and belongs to the UPF0568 family. Expressed in a variety of tissues with particularly high levels in heart and skeletal muscle, CGI-99 functions as a homodimer that interacts with Ninein and is thought to regulate Ninein function. CGI-99 is overexpressed in brain tumor tissue, suggesting a role in tumor development and metastasis. The gene encoding CGI-99 maps to human chromosome 14, which houses over 700 genes and comprises nearly 3.5% of the human genome. Chromosome 14 encodes the presinilin 1 (PSEN1) gene, which is one of the three key genes associated with the development of Alzheimer's disease (AD). The SERPINA1 gene is also located on chromosome 14 and, when defective, leads to the genetic disorder ?-antitrypsin deficiency, which is characterized by severe lung complications and liver dysfunction.