SERPINA3 and early-onset autosomal dominant Alzheimer disease: One transcript fulfilling these criteria is serpin-a3n, the murine homolog of human alpha-1-antichymotrypsin (α1-ACT), a serine proteinase inhibitor which has been previously implicated in the pathogenesis of Alzheimer's disease [17], [18] and which has been reported to be a candidate plasma and CSF biomarker of Alzheimer's disease (AD) [19], [20], [21], [22].