Serum as an alternative to plasma for determining the ApoE4 phenotype using Pan-ApoE and ApoE4 chemiluminescent enzyme immunoassays

Using matrix-specific thresholds, the ApoE4/Pan-ApoE ratio in plasma and serum accurately classified the ApoE4 phenotype in concordance with <i>APOE ε4</i> genotypes. Serum and plasma showed comparable stability and precision. Thus, serum is a reliable alternative to plasma for measuring Pan-ApoE and ApoE4 with the Lumipulse assays. The use of serum expands sample availability, particularly in retrospective studies or when collected alongside cerebrospinal fluid.