Marfan syndrome is an autosomal-dominant connective tissue disorder characterized by pleiotropic manifestations involving the skeletal, ocular, and cardiovascular systems and resulting from mutations in the gene for fibrillin, FBN1. The clinical diagnosis is based on a set of well-defined clinical criteria (Ghent nosology). Nevertheless, the age-related nature of some clinical manifestations and the variable phenotypic expression of the disorder may hamper the diagnosis. In those instances, molecular analysis of the FBN1 gene is helpful to identify at-risk individuals. Mutations are spread over the entire FBNJ gene and there are no particular hot spots. Different standard methodologies are available to identify these mutations, however, one of the most sensitive techniques is denaturing high-performance liquid chromatography. This approach allows the performance of the analysis in a semi-automated manner and has a mutation detection rate of approx 95%.