2.1 Study design and assumption
The MR analysis aimed to assess the causal relationship between the human herpes virus family and leukocytoclastic angiitis. MR analysis relies on three fundamental assumptions:1)The genetic variants chosen as IVs must be significantly associated with the exposure (herpes virus). 2)The IVs should not be correlated with any confounding factors. 3)The IVs should exclusively impact the outcome (leukocytoclastic angiitis) through the exposure, with no alternative pathways(11).