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At a glance

It is a familial disorder characterized by generalized connective tissue abnormalities leading to abnormal tissue weakness with hyperextensible joints, eyes (dislocation of the lens), increased risk of acute aortic valve dissection, and spontaneous pneumothorax. The leading cause of mortality in the infancy period is the progression from mitral valve prolapse to acute regurgitation, often in conjunction with tricuspid regurgitation, leading to congestive heart failure and death.

History

It was first described in 1896 in a 5-year-old girl, Gabrielle P, by Antoine Bernard Jean Marfan (1858-1942), a French pediatrician at Necker Children Hospital in Paris. The girl had disproportionately long limbs, hands, and feet. Marfan used the term “pattes d’araignée” (spider’s legs) and originally called the condition “dolichostenomely” (Greek: stenos = narrow; slender; melos = limb). In 1902, H. Méry and L. Baboneix confirmed radiologically the skeletal anomalies. The first person to use the term “Marfan’s Syndrome” was Henriculus J. M. Weve of Utrecht in 1931.

Incidence

In the United States, this medical condition affects about 1:10,000 individuals and possibly as many as 1:3,000 to 5,000 individuals. It is estimated that in 2004 at least 200,000 people had Marfan Syndrome. Internationally, there are no geographic predilections. It is more frequently observed in males than females.

Genetic inheritance

Autosomal dominant trait with variable expression. Approximately 15% of cases occur sporadically. In less than 1% of cases, it is autosomal recessive.

Pathophysiology

Mutations in the gene for fibrillin-1 on chromosome 15 (15q21.1). This mutation results in an increase in a protein called transforming growth factor beta, or TGF-β. Fibrillin is a major component of microfibrils, which are structural components of the zonular fibers of the lens and associated with elastic fibers in the aorta and skin. Tensile strength of collagen is reduced, while its elasticity is increased. Degeneration of media of the pulmonary artery, aorta, and distal arteries leads to “cystic medial necrosis” and weakness. Aneurysm formation results from this connective tissue disorder. Disproportionate growth of long bones is present, leading to arachnodactyly with hyperextensible joints. Emphysema and spontaneous pneumothorax may occur.

Diagnosis

The thumb and wrist signs are screening tests for the joint hypermobility of Marfan Syndrome. The former is positive when the thumb extends well beyond the ulnar border of the hand when overlapped by fingers, and the latter is positive when the thumb overlaps the fifth finger as they grasp the opposite wrist. The definitive diagnosis is made on clinical grounds; at least two of the four criteria should be present: a positive family history of the condition, the skeletal, cardiovascular, or ocular features. There is no diagnostic laboratory test.

Clinical aspects

In persons younger than 20 years, the prevalence of serious cardiac complications is low, but aortic ...

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