Novel SERPINA1 Alleles Identified through a Large Alpha-1 Antitrypsin Deficiency Screening Program and Review of Known Variants

The gene encodes the serine protease inhibitor alpha-1 antitrypsin (AAT) and is located on chromosome 14q31-32.3 in a cluster of homologous genes likely formed by exon duplication. AAT has a variety of anti-inflammatory properties. Its clinical relevance is best illustrated by the genetic disease alpha-1 antitrypsin deficiency (AATD) which is associated with an increased risk for chronic obstructive pulmonary disease (COPD) and cirrhosis. While 2 single nucleotide polymorphisms (SNPs) , S and Z, are responsible for more than 95% of all individuals with AATD, there are a number of rare variants associated with deficiency and dysfunction, as well as those associated with normal levels and function. Our laboratory has identified a number of novel AAT alleles that we report in this manuscript. We screened more than 500,000 individuals for AATD alleles through our testing program over the past 20 years. The characterization of these alleles was accomplished by DNA sequencing, measurement of AAT plasma levels and isoelectric focusing at pH 4-5. We report 22 novel AAT alleles discovered through our screening programs, such as Z and QO, and review the current literature of known AAT genetic variants.