Compound heterozygosity for alpha-1-antitrypsin (S_iiyama and QO_clayton) in an oriental patient

Alpha-1-antitrypsin (α1AT) deficiency is extremely rare among Orientals. We treated a 37-year-old man with severe pulmonary emphysema associated with a low serum concentration of α1AT. Mutation analysis of the α1AT gene was performed using a reverse transcription-polymerase chain reaction followed by sequencing. The patient proved to be a compound heterozygote carrying a S_iiyama deficient allele and a QO_clayton null allele. This is the first Japanese case of α1AT deficiency to arise from such compound heterozygosity in a family with no apparent consanguineous marriage, suggesting that the gene frequency for deficient alleles might be somewhat higher than previously estimated.