Haplotypes of the alpha‐1 antitrypsin gene in healthy controls and Z deficiency patients

Alpha‐1 antitrypsin (AAT; HUGO symbol, SERPINA1) is one of the major serine protease inhibitors (serpins) in human plasma. Deficiency of AAT is a recognised risk factor for chronic obstructive pulmonary disease (COPD), attributed to uninhibited neutrophil elastase released into the lung tissue during inflammatory states. In this study we used sequencing to screen the exonic regions, 5′ and 3′ flanking sequence of the AAT gene in order to generate a high density map of single nucleotide polymorphisms (SNPs). 16 SNPs were identified throughout AAT. Haplotypes based on SNPs with a minor allele frequency of ≥5% were estimated using genotypic information from 225 healthy control individuals and 41 AAT deficient Pi‐ZZ individuals. AAT shows a large amount of variation in the control population, with 17 haplotypes accounting for 88% of the observed variation. The haplotype distribution of the common deficiency Pi‐Z variant of AAT was significantly different when compared to the normal variants. In addition to the haplotype information, we present evidence for a functional effect of a SNP in intron 1. © 2004 Wiley‐Liss, Inc.