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

Alpha-1-antitrypsin (alpha 1AT) deficiency is extremely rare among Oriental s. We treated a 37-year-old man with severe pulmonary emphysema associated with a low serum concentration of alpha 1AT. Mutation analysis of the alpha 1AT gene was performed using a reverse transcription-polymerase chain reac tion followed by sequencing. The patient proved to be a compound heterozygo te carrying a S-iiyama deficient allele and a QO(clayton) null allele. This is the first Japanese case of alpha 1AT deficiency to arise from such comp ound heterozygosity in a family with no apparent consanguineous marriage, s uggesting that the gene frequency for deficient alleles might be somewhat h igher than previously estimated.