ABSTRACT
The protein and gene of alpha 1-antitrypsin (alAT) are the most studied members of a large family of serine protease inhibitors called serpins. alA T and alpha 1antichymotrypsin (alACT) are known to be located very close together on chromosome 14q32.1. According to recent analysis using a pulsed-field map of the surrounding region of 14q32.1, the alAT gene is only 22 kb away from the alA C T gene (1). Although the alA T gene and the alA C T gene are oriented in opposite directions, the location of the introns within these genes is identical. It seems likely that the divergence of these two loci is a relatively recent eventbetween 100 million (M) years and 250 M years ago (2). Also, because of the comparatively short distance, there is clearly a close genetic linkage between alA T and alACT. Although these are single-copy genes in humans, they are found in mice as clusters and complexed (contrapsin is the mouse equivalent of alACT), indicating that species-specific duplications of these genes occurred independently.
