Genetics¹

• Should Your Patient Be Tested
• Your Newly Diagnosed Patient
• Managing Your AAT Deficient Patient

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View About Chromosome 14 Animation

View Genetics of AAT Deficiency Animation

AAT is encoded by a single gene at the proteinase inhibitor (PI) locus on chromosome 14. AAT deficiency can result from an inherited mutation in this gene that directs the body to synthesize the AAT enzyme.

There are over 100 distinct AAT alleles. PI*M is the normal allele which directs the body to synthesize the normal AAT enzyme. PI*Z and PI*S are the most common deficient alleles. They direct the body to synthesize a version of the AAT enzyme that is nonfunctional. Patients who are homozygous PI*ZZ have the most severe symptoms. Null alleles, which result in no protein synthesis, have also been identified.

It is estimated that worldwide there are 3.4 million people with deficiency allele combinations (PiZZ, PiSZ, PiSS) and 116 million who are carriers (PiMS , PiMZ).²

Carriers may have mild to moderate symptoms, or may have no symptoms at all. Carriers may also have increased risk for lung and liver disorders.²

Because AAT deficiency* is inherited, testing of family members may be recommended when a person is diagnosed with AAT deficiency.

*Also known as Alpha-1, alpha-1 antitrypsin deficiency, AATD, A1-PI deficiency, alpha-1 proteinase deficiency, A1AD, or hereditary or genetic emphysema.