Fibrillin-1 is a multifunctional extracellular protein encoded by the FBN1 gene. FBN1 is 237 kb in size and is located on chromosome 15q21. FBN1 mutations are known to cause Marfan syndrome and other fibrillinopathies. FBN1 is composed of 65 exons and 3 additional alternatively spliced exons at the 5' end. The absence of the peptide sequence from the extreme N-terminus of the fibrillin-1 protein and the presence of in-frame and alternatively spliced exons at the 5' end of the FBN1 gene create some ambiguity about the translation start site and indicate a functional role of these alternatively spliced exons. We demonstrate here the conservation of 5'-upstream region of the FBN1 gene among humans and non-human primates.