to my understanding, the two are linked statistically but as of yet we are uncertain of the specific genetics involved. Having said that I'm of the view that Marfans does indeed feed into BAV and Aneurysm, and the literature notes connections between BAV and Aneurysm ... so it would seem logical that each are expressions of a connective tissue disorder.
A quick google search revealed this:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5469203/
Bicuspid aortic valve (BAV) can be both sporadic and hereditary, is phenotypically variable, and genetically heterogeneous. The clinical presentation of BAV is diverse and commonly associated with a high prevalence of valvular dysfunction producing altered hemodynamics and aortic abnormalities (e.g., aneurysm and dissection). The thoracic aortic aneurysm (TAA) in BAV frequently involves the proximal aorta, including the aortic root, ascending aorta, and aortic arch, but spares the aorta distal to the aortic arch.
(*sorry about those words)
The Mayo has this to say:
https://www.mayoclinic.org/diseases-conditions/marfan-syndrome/symptoms-causes/syc-20350782
The most dangerous complications of Marfan syndrome involve the heart and blood vessels. Faulty connective tissue can weaken the aorta — the large artery that arises from the heart and supplies blood to the body.
- Aortic aneurysm. The pressure of blood leaving your heart can cause the wall of your aorta to bulge out, like a weak spot in a tire. In people who have Marfan syndrome, this is most likely to happen at the aortic root — where the artery leaves your heart.
- Aortic dissection. The wall of the aorta is made up of layers. Dissection occurs when a small tear in the innermost layer of the aorta's wall allows blood to squeeze in between the inner and outer layers of the wall. This can cause severe pain in the chest or back. An aortic dissection weakens the vessel's structure and can result in a rupture, which may be fatal.
- Valve malformations. People who have Marfan syndrome can have weaker tissue than normal in their heart valves. This can produce stretching of the valve tissue and abnormal valve function. When heart valves don't work properly, your heart often has to work harder to compensate. This can eventually lead to heart failure.
I hope that helps.
Hopefully someone who has more specific knowledge will toddle along soon and add to this.
Best Wishes