First is a 297 amino acid protein that contains a putative carboxy-terminal coiled-coil domain. With highest expression in embryonic dorsal retina and, during later embryonic stages, the anterior epithelial cells of the lens, it is suspected that EURL may play a role in cell determination and differentiation. The gene encoding EURL maps to the long arm of chromosome 21, which houses approximately 300 genes and comprises nearly 1.5% of the human genome. Chromosome 21-associated disorders include Alzheimer's Disease, amyotrophic lateral sclerosis and, most notably, Down Syndrome (also known as trisomy 21).