Alpha 1 antitrypsin deficiency

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Alpha 1 antitrypsin deficiency is a rare disorder in which lungs and liver are affected most commonly. In lung it causes emphysema (one of the types of chronic obstructive pulmonary diseases) and in liver it leads to cirrhosis.

Contents

DEFINITION

EPIDEMIOLOGY

HISTORY

PATHOPHYSIOLOGY

CLINICAL MANIFESTATIONS

DIAGNOSIS

TREATMENT

What is alpha 1 antitrypsin deficiency?

Alpha 1 antitrypsin deficiency is a disorder characterized by decreased production of alpha 1 antitrypsin, an enzyme most commonly found in blood and lungs. Deficiency of this enzyme leads to deposition of alpha 1 antitrypsin protein in the liver. This protein protects the liver and lungs from damage and thus its deficiency leads to cirrhosis in liver and emphysema in lungs.

What is the epidemiology?

The people of following regions are most commonly affected by this disease;

u Europe

u Iberian peninsula

u Saudi Arabia

Alpha 1 antitrypsin deficiency remains undiagnosed in most of the cases. Almost one percent of the patients presenting with chronic obstructive pulmonary disease (COPD) are diagnosed with this disorder.

When was the first case diagnosed?

The two renowned physicians of University of Lund, Sweden, Carl Laurel and Sten Eriksson discovered the disease in 1963. They observed that absence of alpha 1 band on electrophoresis lead to causation of emphysema in the individuals at a younger age. The association of this disease with liver was made in 1969 by Dr. Harvey Sharp.

What are the causes or risk factors of this disease?

Although defective genes play the most important role in the causation of this disease, however, role of smoking is equally important. Smokers who have alpha 1 antitrypsin (A1AT) deficiency develop emphysema at a comparatively younger age. Cigarette smoke not only causes irritation and inflammation of the respiratory tract but also decreases the activity of alpha 1 antitrypsin.

What is the pathogenesis of this disease?

The basic abnormality in this disease is deficiency of alpha 1 antitrypsin (A1AT). It inhibits the activity of neutrophil elastase in the lungs. Neutrophile elastase disrupts the normal tissue architecture of lungs leading to emphysema. Normal level of alpha 1 antitrypsin (A1AT) in the blood is 1.5 to 3.5 g/l. In certain phenotypes the levels of alpha 1 antitrypsin (A1AT) is forty to sixty percent of normal and the disease is mild. However, in severe cases, the level reaches to less than fifteen percent of normal.

How does it present clinically?

The common signs and symptoms due to pulmonary involvement are;

u Breathlessness

u Wheeze

u Rhonchi

u Crepitations

u Rales

Patients usually present with recurrent respiratory tract infections and asthma not responding to conventional treatment.

If liver is involved it leads to the signs and symptoms of cirrhosis and liver failure like;

u Jaundice

u Anorexia

u Hematemesis

How to diagnose alpha 1 antitrypsin deficiency?

It is mandatory for the patients presenting with refractory asthma, COPD, necrotizing panniculitis and liver disease to undergo blood alpha 1 antitrypsin (A1AT) levels. This basic testing is done with protein electrophoresis method.

How to treat alpha 1 antitrypsin deficiency?

In Western World, it has been tried to cure this disease with the help of intravenous infusion of alpha 1 antitrypsin. This is known as augmentation therapy. However, most of the studies have not supported this mode of treatment.

Other modalities employed are liver transplant in cases of liver cirrhosis. Moreover, recombinant forms of alpha 1 antitrypsin (A1AT) are being studied these days.

SUGGESTED READING

http://en.wikipedia.org/wiki/Alpha_1-antitrypsin_deficiency

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001178/

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1718832/pdf/v085p00002.pdf

SUGGESTED WATCHING

http://www.youtube.com/watch?v=xCfdfbDj5Qk

About the Author

Dr Ahmad's picture
Author: Dr Ahmad

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