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Testing for Genetic Disorders

Related Genetic Tests

Alpha-1 Antitrypsin Deficiency

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ALPHA-1 ANTITRYPSIN DEFICIENCY

Genetics of Alpha-1 Antitrypsin Deficiency

Inheritance

Everyone has two copies of each gene. We inherit one copy from our mother and one copy from our father. Alpha-1 is a recessive condition. This mean that, in order to develop complications from Alpha-1, people typically must inherit two altered copies of the AAT gene — one from their mother and one from their father.

People who inherit just one altered copy of the AAT gene are called carriers. Carriers typically do not develop complications related to Alpha-1. Some studies have shown that some carriers — especially smokers — can develop lung damage.

Carriers can also pass on the AAT change to their children. If an Alpha-1 carrier has a child with another Alpha-1 carrier, there is a chance — 1 in 4 (or 25%) — that the child will inherit both parents' mutations. Having two mutations significantly increases the chance of developing signs and symptoms of Alpha-1.

About 1 in 10 to 1 in 33 people in the U.S. are thought to be Alpha-1 carriers, but most do not know it. Carriers do not usually develop signs and symptoms of Alpha-1 unless they are also exposed to environmental triggers such as smoking. If someone is a carrier or has a family member with Alpha-1, other family members are at risk for carrying the same genetic changes. Around 116 million people worldwide are Alpha-1 carriers.

Ancestry

Alpha-1 antitrypsin deficiency can affect people of all ethnic backgrounds, but it is more common in people whose families' originate from Europe. That means that people whose families originated from Europe – regardless of whether they now live in North America, Australia, Africa, or anywhere – are at risk for being Alpha-1 carriers.

Studies have also shown that certain gene changes related to Alpha-1 are more common in certain populations. For example, someone of Scandinavian descent has a greater chance of having one of the two genetic changes commonly tested for – S and Z – than someone of Asian descent.

The following lists – from most common to least common – how frequently Alpha-1 is found in certain regions of the world:

Europe
North America
Australia/New Zealand
East Asia

Scientists believe that Alpha-1 may be more common than previously thought in people whose families come from the Middle East, Africa, and Southeast and Central Asia. Currently, no large studies have been done to estimate the frequency of Alpha-1 in South America. Additional studies are needed to determine how common Alpha-1 is among these groups.

When considering your risk for Alpha-1, it is important to consider both your family medical history and your ethnic background.