The PiMZ genotype of the  α-1 antitrypsin (AAT) protease inhibitor gene is highly prevalent, with more than 35 million people in 74 countries carrying it, according to a new review published in the International Journal of Chronic Obstructive Pulmonary Disease. 

PiMZ is a moderately deficient genotype that was thought to cause little or no risk of disease. However, recent research has shown that people with this genotype have an increased risk of developing lung and liver diseases if exposed to smoke, pollutants, and hepatotoxic substances such as alcohol.

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More than 120 variants of the SERPINA1 gene, which codes for AAT, have been identified, around 40% of which cause AAT deficiency (AATD). People with 1 normal allele of SERPINA1 and 1 PiMZ allele express about 55% of the AAT protease inhibitor, which plays an essential role in neutralizing excess free elastase and proteinase 3 from activated neutrophils to avoid the excessive degradation of elastin and collagen IV in lung connective tissue.

Here, a team of researchers from Spain conducted a literature review to update the epidemiological data about the prevalence and number of PiMZ genotypes, as well as smoking rates, in 74 countries for which data was available.

They found that the number of PiMZ carriers was between 2% and 4% of the population of European heritage living in Europe, America, Australia, and New Zealand, corresponding to around 35 million people.

“Considering the high rate of smoking, the outdoor and the indoor air pollution from solid fuels used in cooking and heating, and the exposure to industrial dusts and chemicals in many of these countries, these figures are very worrying,” the researchers wrote.

They added that it is of great importance to adequately assess PiMZ carriers to recommend that they adopt a healthy lifestyle and avoid smoking and alcohol to reduce the risk of developing diseases associated with AATD.


Martinez-González C, Blanco I, Diego I, Bueno P, Miravitlles M. Estimated prevalence and number of PiMZ genotypes of alpha-1 antitrypsin in seventy-four countries worldwide. Int J Chron Obstruct Pulmon Dis. 2021;16:2617-2630. doi:10.2147/COPD.S327803