However, the CSF/serum IgM ratio was higher in both possible pAE (1.06 ± 0.71) and definitive pAE (1.33 ± 0.86) than in AD patients (0.75 ± 0.57) (Mann Whitney U test, p < 0.05), but was below the cut-off value for intrathecal IgM synthesis in all patient groups (Table 1). The gene discussed is CD40LG; the disease is Alzheimer disease.