Marfan’s Disease

Pathophysiology of Marfan’s disease

Marfan’s disease is

1) disease of connective tissue
2) marked by dilation of aorta and aortic dissection in a young person

Signs and Symptoms

1) tall stature with long lower torso
2) long limbs and digits
3) pectus carinatum (pigeon breast)
4) inguninal hernias
5) hypermobile joints
6) severe chest pain
7) lightheadedness
8) retinal detachment
9) myopia
10) bilateral subluxation of lines in outward and upward direction (ectopia lentis)
11) aortic regurgitation
12) mitral prolapse and “floppy” mitral valve
13) abnormal head (enlarged supraorbital ridges)
14) kyphosis/scoliosis

Characteristic Test Findings

Radiology

1) apical lung blebs on chest radiograph

Echocardiogram

2) enlarged aortic root
3) mitral valve prolapse and regurgitation
4) aortic dissection

Histology/Gross Pathology

fragmentation of elastic fibers in aortic media (cystic medial necrosis)

Associated Conditions

1) spontaneous pneumothorax
2) attention deficit disorder

Biochemistry

1) FBN1 gene codes for the extracellular glycoprotein fibrillin 1, a major component of microfibrils
2) if microfibril is abnormal, elastin cannot be correctly deposited on i

Inheritance/Epidemiology

1) automsomal dominant (75-85%) with some sporadic cases occurring
2) wide variation in clinical phenotype
3) occurs in 1/10,000 births
4) defect is usually a missense mutation occurring in the FBN1 gene (15q21.1)

Treament

1) ARB and ACE class drugs are being used early in the disease course to arrest development

traditional care of Marfan’s disease before advent of above drugs

2) restriction from contact sports and strenuous exercise
3) regular surveillance of aortic root with replacement when diameter > 50 mm
4) reduction of systolic blood pressure with beta blockers
5) urgent repair of aortic dissections when diagnosed, even if miniscule
6) endocarditis prophylaxis for all dental procedures

Tips for USMLE

1) if a tall young man who is severely nearsighted has abdominal or chest discomfort and a murmur consistent with aortic regurgitation arrives at the ER, think Marfan’s disease
2) if a patient is able to hyperextend the thumb back to the writs, think Marfan’s disease
3) if bilateral lens subluxation or ectopia lentis is mentioned, think Marfan’s disease