Alpha-1 Antitrypsin Deficiency

Snapshot

• A 23-year-old man with a past medical history of depression presents to his primary care physician for increasing shortness of breath. He reports that this occurs especially when he exercises. His family history is pertinent for lung disease in multiple family members, but he is not sure which lung disease. He reports that when he smokes socially, the shortness of breath becomes acutely worse. A chest radiograph shows a flattened diaphragm, and laboratory evaluation reveals increased lever enzymes. He is sent to the genetic counselor for genetic testing.

Introduction

• Clinical definition
  • alpha-1 antitrypsin deficiency is characterized by
    • early-onset emphysema
    • cirrhosis
• Epidemiology
  • demographics
    • young adults
      • often without a history of smoking
  • risk factors
    • family history
    • smoking exacerbates illness
• Pathogenesis
  • alpha-1 antitrypsin is a serine protease inhibitor synthesized in the liver
    • inhibits proteolysis by enzymes, particularly elastase
  • decrease or dysfunctional alpha-1 antitrypsin is usually caused by misfolded gene product
    • increased proteolysis of alveoli by neutrophil elastase
    • accumulation of the misfolded alpha-1 antitrypsin polymers in hepatocytes
    • proteolysis and damage to vessels may cause vasculitis
• Genetics
  • autosomal codominant
• SERPINA1 gene

Presentation

• Symptoms
  • chronic obstructive pulmonary disease (COPD)
    • onset at age 40-50 years
    • dyspnea on exertion
    • wheezes
    • cough
    • sputum production
  • liver disease that may progress to cirrhosis
    • onset in childhood
    • hepatomegaly
• abdominal pain

Imaging

• Chest radiograph  
  • findings
    • flattened diaphragm
• Computed tomography of chest 
  • findings
• panacinar emphysema

Studies

• Serum labs
  • ↑ prothrombin time
  • ↓ alpha-1 antitrypsin level
  • ↑ liver enzymes
  • genetic testing
    • confirms diagnosis
• Invasive studies 
  • liver biopsy 
    • findings  
      • PAS+ globules in hepatocytes 
• Diagnostic criteria
• diagnosed with ↓ alpha-1 antitrypsin levels and confirmed with genetic testing or liver biopsy

Differential

• Asthma 
  • distinguishing factor
    • typically not associated with liver disease and presents at a younger age
• Autoimmune hepatitis 
  • distinguishing factor
• typically not associated with COPD or ↓ alpha-1 antitrypsin levels

Treatment

• Lifestyle
  • minimize alcohol consumption
• Medical
  • vaccinations
    • influenza
    • pneumococcus
  • alpha-1 antitrypsin infusion
    • indication
      • patients with symptoms of COPD
  • standard COPD treatment
• Surgical
  • liver transplant
    • indication
      • decompensated cirrhosis
      • hepatocellular carcinoma
    • outcomes
• liver transplant will help patients maintain normal levels of donor’s alpha-1 antitrypsin

Complications

• Hepatocellular carcinoma
  • regular surveillance
    • liver ultrasound
    • alpha-fetoprotein