Compound heterozygosity for alpha-1-antitrypsin (S(iiyama) and QO(clayton)) in an Oriental patient.

Alpha-1-antitrypsin (alpha1AT) deficiency is extremely rare among Orientals. We treated a 37-year-old man with severe pulmonary emphysema associated with a low serum concentration of alpha1AT. Mutation analysis of the alpha1AT 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 alpha1AT 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.