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在北欧约1/2,000～3,000人发生α-1-抗胰蛋白酶(AAT)缺陷,多数个体血浆中α-1-抗胰蛋白酶水平正常,为蛋白酶抑制因子(PI)M 型纯合子,而血浆中α-1-抗胰蛋白酶水平低下的个体,通常具有 Z 等位基因,这是由于 AAT 基因中 G 替代 A,这种突变是多肽链342位置上谷氨酰胺转变成赖氨酸,通过寡核苷酸探针杂交可检测出这种突变。Z 等位基因使 AAT 的变异体表达,而这种变异体在正常情况下肝脏并不分泌。PI 型 ZZ 等位基因个体对阻塞性肺疾患具有高风险,有13%AAT缺陷个体在儿童期发生严重肝硬化,如果 PI ZZ 同胞曾患严重肝疾患,那么 PI ZZ 胎儿发生肝硬化的风险为40%,此类家族需进行产前诊断。
Alpha-1-antitrypsin (AAT) deficiency occurs in about 1 in 2,000 to 3,000 persons in Northern Europe. Most individuals have normal levels of alpha-1-antitrypsin in protease inhibitor (PI) type M homozygotes, whereas plasma Individuals with low alpha-1-antitrypsin levels usually have the Z allele due to the G substitution for A in the AAT gene, which is the conversion of glutamine to lysine at position 342 in the polypeptide chain, This mutation can be detected by the hybridization of the nucleotide probe. The Z allele expresses a variant of AAT that is not normally secreted by the liver. Individuals with PI-ZZ allele are at high risk for obstructive pulmonary disease, 13% of AAT-deficient individuals develop severe cirrhosis in childhood, and PI ZZ fetuses have cirrhosis of the liver if PI ZZ siblings had severe liver disease 40%, such families need to be prenatal diagnosis.