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Keywords:

  • alpha-1-antitrypsin;
  • deficiency;
  • Pi-Z phenotype: M-like;
  • M-Cagliari;
  • DNA analysis

Abstract: This paper reviews the genetic variants of alpha-1-antitrypsin (AAT) which have been sequenced with special emphasis on the s.c. deficiency variants. These result in AAT low plasma levels via three main mechanisms: 1) intracellular storage; 2) intracellular degradation; 3) lack of synthesis. Intracellular storage occurs with the classical Z variant and with a few variants called M-like, because of their isoelectric focusing (IF) pattern. The storage phenomen causes liver damage and can be demonstrated at both light and electron microscopic level with the help of immuno-histochemistry. We report a new deficiency variant of AAT (M-Cagliari) characterized by very low plasma levels, massive storage of AAT and liver cirrhosis. By using immunohistochemical techniques and DNA analysis we could demonstrate that M-Cagliari has antigenic and genetic properties other than the Z AAT.