SERPINA1 and lung disorder: The focus of the meeting was to describe and assess what is known about the relative risks of liver and/or lung disease for heterozygotes and to identify future avenues of research into disease mechanisms and clinical phenotypes in MZ heterozygotes.<h4>Results</h4>Population-based and family studies of individuals heterozygous for the AATD Z risk allele demonstrate that a proportion of these individuals have relatively higher risk for lung or liver disease than do individuals harboring no variants in SERPINA1.