It is of interest that α1AT, which is a serpin with known associations to AD in blood [58–60], CSF [61, 62] and senile plaques [63] also correlated with the APOE ε4 allele (Fig. 4B), however the specific physiological role of α1AT in tissues is not well elucidated. This evidence concerns the gene SERPINA1 and Alzheimer disease.