Marfan Syndrome

The parents of a 10-year-old boy of normal intelligence brought him for evaluation because of his tall stature. He was 154 cm tall (3 cm above 97th percentile) and weighed 34.3 kg (50th percentile). He exhibited significant arachnodactyly, with an upper to lower segment ratio of 0.8 and an arm span to height ratio of 1.1. He had a long, angular face with a high arched palate and crowded dentition, ptosis, myopia, superior lens subluxation, pectus excavatum, widely spaced and low-set nipples, grade 2/6 ejection systolic murmur at the left sternal border, midthoracic scoliosis, joint hypermobility, positive thumb sign and wrist sign, and pes planus.

The child has Marfan syndrome, an autosomal dominant connective tissue disorder with nearly complete penetrance but variable expressivity. Approximately 15% to 30% of cases are sporadic and arise by new mutation. The clinical manifestations are divided into major and minor criteria.¹

Skeletal system. Major criteria: The presence of at least 4 of the following manifestations:

• Pectus carinatum (pigeon breast).
• Pectus excavatum (funnel chest) severe enough to require surgical correction.
• Reduced upper to lower segment ratio, or arm span to height ratio greater than 1.05.
• Wrist sign or thumb sign (Steinburg sign).
• Scoliosis greater than 20 degrees or spondylolisthesis.
• Reduced extension at the elbows (less than 170 degrees).
• Pes planus.
• Protrusio acetabuli.

Minor criteria: Moderate degree of pectus excavatum; joint hypermobility; high, narrow palate; and abnormal facial appearance (dolichocephaly, malar hypoplasia, enophthalmos, retrognathia, and antimongoloid slants).

Ocular system. Major criterion: Ectopia lentis (dislocation of lens).

Minor criteria: Flat cornea, increased axial length of globe, and hypoplastic iris or ciliary muscle resulting in decreased miosis.

Cardiovascular system. Major criteria: Dilatation of the ascending aorta with involvement of the sinuses of Valsalva or dissection of the ascending aorta.

Minor criteria: Mitral valve prolapse, dilation of the pulmonary artery, calcification of the mitral annulus before age 40 years, and dilation or dissection of the descending aorta before age 50 years. Pulmonary system. Major criterion: None.

Minor criteria: Striae atrophicae (stretch marks) not associated with marked weight changes or pregnancy, and recurrent or incisional hernias.

With a positive family history, the diagnosis is based on the presence of 1 major criterion in an organ system and involvement in a second organ system. In the absence of an unequivocal positive family history, diagnosis requires major criteria in at least 2 different organ systems and involvement of a third organ system.

There is no specific treatment. The prognosis varies and depends on the severity and extent of organ involvement.

REFERENCE:1. American Academy of Pediatrics Committee on Genetics. Health supervision for children with Marfan syndrome. Pediatrics. 1996;98:978-982.