Direct Search for Nucleotide Substitutions Responsible for Defects of Alpha 1-Antitrypsin Molecules in Patients with Pulmonary Emphysema.

蛋白酶-抗蛋白酶失衡导致下呼吸道中包括弹性蛋白在内的组成蛋白的慢性破坏的概念来自于α 1-抗胰蛋白酶（α 1AT）缺乏和肺气肿（PE）早期发作病例的发现。然而，大多数PE患者的α 1 AT水平正常，这表明α 1 AT分子结构变化引起的功能失衡可能是导致破坏的原因。本研究通过对PE患者α 1 AT基因的氨基酸编码区进行沿着直接测序来验证这种可能性。虽然我们选择了10例患者（50-60岁）。o.）在PE相对较早发作的情况下，我们仅发现与正常α 1AT变体相同的核苷酸替换，但没有导致肺气肿的氨基酸替换。相比之下，38岁。O.对1例α 1AT缺乏症合并肺气肿的男性患者进行α 1AT基因分析。第二外显子有C → T的突变，导致Ser^<53>（TCC）→ Phe^<53>（TTC）突变。在等电聚焦上，该新变种移到S位，因此以其出生地命名为Siiyama。有趣的是，使用等位基因特异性PCR，在日本报道的9个α 1AT缺陷家族中，另外4个独立的家族显示具有相同的核苷酸替换，这表明这种变体可能在日本很常见。在这种情况下，Z变体（... Ala^<213>.. Lys^<342>.）。在高加索人中的一种高频率的缺陷变体，在日本没有发现，我们使用BstPI（G/GANTCC）分析了Ala^<213>（GCG）到瓦尔^<213>（GTG）的正常和进化的旧替换，发现所有分析的156个日本人都有瓦尔^<213>。这表明，日本人（可能还有其他东方人）在史前时代就与高加索人隔离开来，几乎没有保留旧的Ala^残基的Z变体<213>。

The concept that the protease-antiprotease imbalance leads to the chronic destruction of the constituent proteins including elastin in the lower respiratory tracts came from the discovery of cases with alpha1-antitrypsin (alpha1AT) deficiency and early onset of pulmonary emphysema (PE). Most patients with PE, however, have normal levels of alpha1AT, suggesting one possibility that functional imbalance due to the structural changes in the alpha1AT molecule is responsible for destruction. In this study we examined this possibility by direct sequencing along the amino acid coding regions of alpha1AT gene in patients with PE. Although we selected 10 patients (50-60 y. o.) with relatively early onset of PE, we only found same nucleotide substitutions as in the normal alpha1AT variants but no amino scid substitutions responsible for emphysema. In contrast, a 38 y. o. male with alpha1AT deficiency and emphysema was refereed and his alpha1AT gene was analyzed. There was C to T substitution in the second exon causing Ser^<53> (TCC) to Phe^<53> (TTC) mutation. This new variant migrated to S position on isoelectric focusing thus is designated as Siiyama after hia birthplace. Interestingly, using allele specific PCR, 4 other independent families among 9 alpha1AT deficient families reported in Japan were shown to have the same nucleotide substitution, suggesting this variant might be frequent in Japan. In the context of that the Z variant (.. Ala^<213>.. Lys^<342>..). a high frequent deficient variant among Caucasians, is not found in Japan, we analyzed the normal and evolutionary old substitution of Ala^<213>(GCG) to Val^<213>(GTG) using BstPI (G/GANTCC) and found all 156 Japanese analyzed have Val^<213>. This indicates that Japanese (and probably other Oriental peoples) are segregated from Caucasians somehow in the prehistoric era and hardly have the Z variant which keeps old Ala^<213> residue.