Bicuspid, or bicommissural, aortic valve (BAV) describes an aortic valve with 2 rather than 3 leaflets (Cripe et al., 2004). In 1 to 2% of the population a bicuspid aortic valve is present. Bicuspid aortic valve is frequently an antecedent to aortic valve stenosis or insufficiency. In extreme cases the blood flow may be so restricted that the left ventricle fails to grow, resulting in hypoplastic left heart syndrome (241550) (Garg et al., 2005). The valve calcification often observed in bicuspid aortic valve is a result of inappropriate activation of osteoblast-specific gene expression. Mutations in the signaling and transcription regulator NOTCH1 cause a spectrum of developmental aortic valve anomalies and severe valve calcification in nonsyndromic autosomal dominant human pedigrees.
Genetic Heterogeneity of Aortic Valve Disease
Also see AOVD2 (614823), caused by mutation in the SMAD6 gene (602931) on chromosome 15q22, and AOVD3 (618496), caused by mutation in the ROBO4 gene (607528) on chromosome 11q24. There is evidence for additional genetic heterogeneity (see MAPPING). [from
OMIM]