Marfan

Autosomal dominant involving chrom. 15q21.1; abnormal fibrillin.

Characteristics

• skeletal: tall stature w/ long thin limbs, hypotonia, arachnodactyly, joint laxity, scoliosis, pectus excavatum
• ocular: lens subluxation/ectopia lentis, myopia
• CV: dilatation of ascending aorta, AR, MVP
• spontaneous pneumothorax; high arched palate; striae and hernias
• average life expectancy is halved
• there is also a severe neonatal form
• + thumb sign. When wrapping thumb inside fist, thumb protrudes past ulnar edge

Diagnostic Criteria

• 1st degree relative with Marfan AND involvement of two systems
• IF no first degree relative, then need involement of skeleton AND at least 2 other systems, each with a major manifestation (i.e, dislocated lenses (they are dislocated upward), aortic dissection or root dilatation, dural ectasia
• negative test for Homocystinuria (cyanide nitroprusside) - these kids have more behavior problems
  • Homocystinuria vs Marfan
    • lax joints in Marfan; tight joints in homocystinuria
    • lens dislocation - upward in Marfan, downward in homocystinuria
    • aorta dilatation in Marfan
    • thrombembolism, mental retardation, and psychiatric disturbance in homocystinuria
    • inheritance (AD in Marfan, AR in homocystinuria)

Management

• all should have regular f/u w/ cardiology
• propranolol therapy reduces the incidence of aortic root dilatation (Pyeritz et al, 1989).

CHLA board review course 2005
Baraitser and Winter, 1996. Color Atlas of Congenital Malformation Syndromes