COL4A2 and periodontal disorder: Meanwhile, macrophage levels were significantly higher in periodontitis samples than in healthy samples [40], they are central players in the destruction and repair phases of periodontal disease [41].COL4A2, which encodes the α2 chain of type IV collagen, is a major structural component of basement membranes (BMs) and plays a fundamental and crucial role in vessel wall integrity; Abnormal COL4A2 expression can lead to a broad phenotypic spectrum involving the nervous system, kidneys, and other organs, but the main site of vascular damage is the brain[42, 43].