Alpha-1 antitrypsin deficiency is a hereditary disease that causes emphysema and cirrhosis and is diagnosed by identifying magenta inclusions in liver cells using a periodic acid – Schiff (PAS) stain.

Alpha 1-antitrypsin (AAT) deficiency is a hereditary and progressive disease first described in 1963. Alpha 1-antitrypsin deficiency affects about 1 in 2000 people, but only approximately 2 to 10% of people with the disease are correctly diagnosed. As a result, patients with AAT deficiency may come to the attention of the local medical examiner due an unexplained and premature death. Although affected individuals produce alpha 1-antitrypsin, an enzyme that prevents breakdown of tissues, they cannot pass the protein from their liver cells to other tissues where it is needed. A special stain called periodic acid-Schiff (PAS) highlights the trapped proteins within the liver cells, coloring them
magenta against a light purple background.

The most common result of AAT deficiency is pulmonary emphysema (progressive damage of the air sacs in the lung) that begins between ages 30 and 50. The effects of AAT deficiency are made much worse by smoking. Less commonly, affected patients develop scarring of the liver, called cirrhosis. Although the complications of AAT deficiency result in an entirely natural death, determining the correct cause of death is critical for surviving family members. Early diagnosis and intervention are needed for effective treatment. Because people with AAT deficiency have no noticeable symptoms until middle age, they have no cause to seek medical treatment until the disease is irreversible.