In the AD-P dementia group, levels were more clearly decreased compared to control-N subject (p < 0.001), and levels were also significantly lower in this group compared to control-P (p < 0.0001), SCD-P (p < 0.0001), MCI-P (p < 0.0001) (Fig. 3A). Here, OCA2 is linked to Schnyder corneal dystrophy.