PVRL2 is located 17 kb downstream from the apolipoprotein E (APOE) gene and has also been associated with severity of multiple sclerosis (Evangelou et al., 1999; Schmidt et al., 2002), late-onset Alzheimer’s disease (Corder et al., 1993), and peripheral T-cell lymphomas (Liestol et al., 2000). Here, APOE is linked to Alzheimer disease.