Table 6. The allele frequency of the p21cip1 variant in groups defined by the severity of AD.

Diagnosis	Variant allele count	Common allele count	Variant allele frequency
Pre-clinical	4	72	0.052
Mild AD	7	125	0.053
Advanced AD	14	158	0.081

The diagnosis was defined according to the Braak staging system: with entorhinal, limbic and neocortical stage subjects in a pre-clinical, mild and advanced stage of AD respectively.