SERPINA3 and Alzheimer disease: Using age-at-onset (AAO) as a covariate for AD, a linkage signal with a lod score of 1.89 was detected near at 90.7 Mbp (D14S1015) on chromosome 14q32.1, which was within 2 Mbp of ACT or SERPINA3 gene (at 93.0 Mb) but 19 Mbp distal to the PRESINILIN 1 (PSEN1) (at 71.6 Mbp) [37].