EGFL3 (epidermal growth factor-like protein 3), also known as MEGF6 (multiple epidermal growth factor-like domains protein 6), is a 1,541 amino acid secreted protein containing twenty-seven EGF-like domains and an EMI domain. Existing as two alternatively spliced isoforms, the gene encoding EGFL3 maps to human chromosome 1p36.32. The largest human chromosome, spanning about 260 million base pairs and making up 8% of the human genome, chromosome 1 contains about 3,000 genes. The rare aging disease Hutchinson-Gilford progeria, as well as Stickler syndrome, Parkinsons, Gaucher disease and Usher syndrome, are associated with chromosome 1.