[Marfan syndrome].

Marfan syndrome is a genetic illness, generally linked to an anomaly in fibrillin type 1, which is transmitted in an autosomally dominant fashion. Its diagnosis is sometimes difficult and should always be evoked in the face of a non-atheromatous aneurysm of the ascending aorta, lead to family screening in the search for aneurysms in any relatives, and an ophthalmological and rheumatological examination in the search for extracardiac signs. The diagnosis made, the dilatation of the aorta can be limited by proscribing violent sports and prescribing beta-blockers. The diameter of the ascending aorta should be measured with an annual ultrasound in order to propose a surgical replacement of the ascending aorta, before a complication (above all aortic dissection) arises.