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Risk of lung and liver disease for MZs

People with the MZ genotype do not have severe AATD but are genetic carriers of the Z mutation. The Z mutation is a deficiency allele (version of the gene) that reduces the quantity of alpha-1 antitrypsin (AAT) in the blood, and causes AATD in people with two mutations (e.g. ZZ, SZ). The MZ genotype is not associated with an increased risk for lung disease in nonsmokers. Higher risk is seen in MZ individuals who smoke. A slightly increased risk for liver disease has been seen in MZ populations.

Because Alpha-1 is a genetic condition, your result means that your relatives are at increased risk to also have abnormal alpha-1 genes. We encourage you to make your family members and any reproductive partner aware of your result and the availability of testing. Reproductive partners of people with abnormal alpha-1 genes should be offered testing to assess risk to children.

Alpha-1 at MUSC – Genetic Counseling

• the most common clinically significant allele
• causes misfolding of antitrypsin in the liver – making normal quantities of the protein but it misfolds, gets stuck to others and forms polymers which get stuck in the liver.
• 85% trapped in the liver
• originated in Scandinavia
• estimated that 2-3% of people in North America have one copy of the Z allele

What is Your Phenotype and What Does it Mean? – Kimberly Foil, MS, CGC, Genetic Counseling Program, Alpha-1 Foundation; Division of PulmonaryMedical term referring to the lungs. and Critical Care Medicine, Medical University of South Carolina (MUSC)