Marfan syndrome is a systemic connective tissue disease characterized by the variable association of cardiovascular, musculoskeletal, ocular, and pulmonary symptoms. The estimated prevalence is 1/5,000, with no difference between the sexes. Symptoms can occur at all ages and vary considerably among affected people, even within the same family. Cardiovascular involvement is characterized by: 1) progressive dilation of the aorta, associated with an increased risk of aortic dissection. Aortic dilatation can result in insufficiency of the aortic valve; 2) mitral valve insufficiency, which can be complicated by arrhythmias, endocarditis or heart failure. The involvement of the skeleton is often the first sign of the disease and includes excessive length of the extremities, being overweight, arachnodactyly, hypermobility of the joints, scoliosis, and deformity of the chest or maxillary region. The ocular signs include detachment of the retina and dislocation of the lens. Eye complications can result in blindness. Skin signs (stretch marks) may be present, and the risk of respiratory complications is increased. In most cases, Marfan syndrome is caused by mutations in the FBN1 gene (15q21) which encodes fibrillin-1, an essential connective tissue protein. Some borderline clinical forms are due to mutations in the TGFBR2 gene, located on chromosome 3, which codes for a TGF-beta receptor. Transmission is autosomal dominant: it is sufficient to have a single copy of the gene mutated to manifest the condition. A pharmacological treatment has recently been proposed (with ACE inhibitors) which seems to give excellent results also in terms of prevention of complications.
Ehlers-Danlos syndrome (EDS) includes a heterogeneous group of hereditary connective tissue diseases, characterized by joint hyperclass, hyperelastic skin and tissue fragility. The classic type (which includes EDS types 1 and 2) is characterized by the following major diagnostic criteria: hyperextensibility of the skin, atrophic skin scars due to tissue fragility and joint hyper-class. Other minor symptoms are joint subluxations, muscle hypotonia and the presence of family history of the disease. The prevalence of the classic type is estimated at 1:30,000. In most cases, the transmission is autosomal dominant: it is sufficient to have a single copy of the gene mutated to manifest the condition.