Differential Diagnosis in Patients < 20 years

• Non-specific Connective Tissue Disorder – If insufficient systemic features (< 7) and/or borderline aortic root measurements (Z < 3) are present (without FBN1 mutation), we suggest to use the term “non-specific connective tissue disorder” until follow-up echocardiographic evaluation shows aortic root dilation (Z ≥ 3).

• Potential Marfan Syndrome – If an FBN1 mutation is identified in sporadic or familial cases but aortic root measurements are still below Z=3, we propose to use the term “potential MFS” until the aorta reaches threshold.

Differential Diagnosis in Patients ≥ 20 yrs

• Ectopia Lentis Syndrome = Ectopia lentis with or without Syst AND with an FBN1 not known with Ao or no FBN1. If ectopia lentis is found with an FBN1 mutation that  is not unequivocally associated with cardiovascular disease in either a related or unrelated proband, the patient should be classified as “ectopia lentis syndrome”.

• MASS = Myopia, Mitral valve prolapse, Aortic root dilatation, Aortic aneurysm syndrome, Striae, Skeletal findings = Ao (Z < 2) AND Syst (≥ 5) without ectopia lentis. The diagnosis of MASS is made in individuals with an aortic root size below Z=2, at least one skeletal feature and a systemic score ≥5. The presence of ectopia lentis precludes this diagnosis. If an FBN1 mutation is identified in a MASS patient, this patient has the potential to evolve into Marfan syndrome but it is currently unknown how often and which factors predict this transition over time.

• MVPS = Mitral Valve Prolapse Syndrome – Mitral valve prolapse AND Aortic root dilation (Z < 2) AND Syst (< 5) without ectopia lentis. When mitral valve prolapse is present in association with limited systemic features (score < 5), we suggest to use the term mitral valve prolapse syndrome (MVPS). In addition to prolapse of the mitral leaflets, MVPS commonly includes pectus excavatum, scoliosis and mild arachnodactyly. However, aortic enlargement and ectopia lentis preclude this diagnosis.