TARSL1 Background Information TARSL1, also known as TARS2 (threonyl-tRNA synthetase 2, mitochondrial) or ThrRS (threonine--tRNA ligase), is a 718 amino acid mitochondrial matrix protein that belongs to the class-II aminoacyl-tRNA synthetase family. The gene encoding TARSL1 maps to human chromosome 1q21.3. Chromosome 1 is the largest human chromosome spanning approximately 260 million base pairs, 3,000 genes, and making up 8% of the human genome. The rare aging disease Hutchinson-Gilford progeria is associated with the LMNA gene located on chromosome 1. When defective, the LMNA gene product can build up in the nucleus and cause characteristic nuclear blebs. The MUTYH gene, also located on chromosome 1, is partially responsible for familial adenomatous polyposis. Stickler syndrome, Parkinsons, Gaucher disease and Usher syndrome are also associated with chromosome 1. A breakpoint has been identified in 1q which disrupts the DISC1 gene and is linked to schizophrenia. Aberrations in chromosome 1 are found in a variety of cancers including head and neck cancer, malignant melanoma and multiple myeloma.