AKD1 is a 1,911 amino acid coiled-coil protein belonging to the adenylate kinase family. AKD1 exists as six alternatively spliced isoforms and is encoded by a gene that maps to human chromosome 6q21. Chromosome 6 makes up nearly 6% of the human genome and contains 170 million base pairs, which encode 1,200 genes. Deletion of a portion of the q arm of chromosome 6 is associated with early onset intestinal cancer, suggesting the presence of a cancer susceptibility locus. A bipolar disorder susceptibility locus is also linked to the q arm of chromosome 6. The PARK2 gene, which is associated with Parkinson's disease, and the genes encoding the major histocompatiblity complex proteins are located on chromosome 6. Stickler syndrome, 21-hydroxylase deficiency and maple syrup urine disease are also associated with genes on chromosome 6.