This phenomenon that distinct mutations result in strikingly different phenotypes has also been observed in other syndromes i.e. PTEN mutations cause Cowden syndrome (CS) and Bannayan-Riley-Ruvalcaba syndrome (BRRS) and Proteus syndrome (PS)[10], while FBN1 underlies Marfan syndrome, Weill-Marchesani syndrome (WMS) and acromicric dysplasia.[11, 12]. The gene discussed is FBN1; the disease is Marfan syndrome.