INHERITED VARIANTS OF α1-ANTITRYPSIN: A NEW ALLELE PiN

Abstract

A new inherited variant of α1-antitrypsin (protease inhibitor or Pi) has been found in five individuals of a family of Welsh origin. The new allele is called PiN, as the α1AT product migrates in acid starch gel between the products of the PiM and PiP alleles. The individuals carrying the PiN allele are all of Pi type MN. The new variant has been compared in several electrophoretic systems with other variants migrating in a similar region by acid starch gel electrophoresis (M, P, S, V, W and X). Acid starch gel and crossed antigen-antibody electrophoresis are most suitable for distinguishing the PiN product. By immunofixation electrophoresis, N has a mobility only slightly different from that of M, however the value of this method can be seen for distinguishing other slow variants which cannot be clearly distinguished on acid starch gels. Twenty-three variants of α1AT are now known. Twenty-two of these are electrophoretic variants and one, the null allele (Pi−), produces no α1AT.