Two anti-neoepitope antibodies were used to detect ADAMTS-specific cleavage of aggrecan and versican in MFS: the aggrecan neoepitope antibody detects the neoepitope sequence NITEGE, generated by ADAMTS-cleavage at the position Glu392-Ala393 in the core protein; the versican neoepitope antibody detects the neoepitope sequence DPEAAE, generated by ADAMTS-cleavage at the position Glu441-Ala442 of the protein core of versican isoform V1.33 Detection of both neoepitopes was higher in the GuHCl fraction of patients with MFS compared with control but only versican reached statistical significance. The gene discussed is VCAN; the disease is Marfan syndrome.