Rare diseases · Sign or symptom

Bicuspid aortic valve

Aortic valve has two leaflets rather than three

HP:0001647

What it means

The presence of an aortic valve with two instead of the normal three cusps (flaps). Bicuspid aortic valvue is a malformation of a commissure (small space between the attachment of each cusp to the aortic wall) and the adjacent parts of the two corresponding cusps forming a raphe (the fused area of the two underdeveloped cusps turning into a malformed commissure between both cusps; the raphe is a fibrous ridge that extends from the commissure to the free edge of the two underdeveloped, conjoint cusps).

A normal aortic valve is composed of three aortic-valve cusps, each semilunar in appearance. The leaflets are housed within a small dilatation of the proximal aorta associated with each cusp, called the sinuses of Valsalva or aortic sinuses, and their association with the respective coronary ostia identifies them: left, right, and non-coronary sinuses. Each cusp is attached to the wall of the aorta by the outward edges of its semicircular border, and the attachment point between each leaflet is called a commissure [PMID:24827036].

Rare diseases that can present with this48

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Bicuspid aortic valve

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This page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.