The diagnosis of these conditions relies on associated phenotypic traits and genetic tests: acrogeric dysmorphy, distal joint laxity and tiny skin elasticity in vascular Ehlers-Danlos syndrome (confirmed by detection of COL3A1 gene mutations) [40]; facial dysmorphy, supra-aortic stenosis and particular behavior in Williams syndrome (confirmed by detection of deletion 7q1.2 using FISH method) [41]; and specific skin lesions in neurofibromatosis 1 [42]. This evidence concerns the gene COL3A1 and aortic stenosis.