Methods for assessing risk of developing a viral disease using a genetic test

A method of treating a condition in a subject in need of natalizumab therapy, comprising:

• administering a therapeutically effective amount of natalizumab to the subject, wherein the subject has a decreased risk of progressive multifocal leukoencephalopathy (PML) due to an infection of the brain by John Cunningham virus (JCV), wherein the subject's decreased risk is associated with an absence of one or more genetic variations in the subject, wherein the subject has been tested for a presence of the one or more genetic variations with a genetic assay and has been identified as not having the one or more genetic variations,
• wherein the one or more genetic variations disrupt or modulate a gene selected from the group consisting of homo sapiens chromodomain helicase DNA binding protein 7 (CHD7), homo sapiens interferon induced with helicase C domain 1 (IFIH1), homo sapiens immunoglobulin lambda like polypeptide 1 (IGLL1), homo sapiens mitochondrial antiviral signaling protein (MAVS), homo sapiens phospholipase C gamma 2 (PLCG2), homo sapiens SHANK-associated RH domain interactor (SHARPIN), homo sapiens T-cell immune regulator 1, ATPase H+ transporting V0 subunit a3 (TCIRG1), and any combinations thereof, and
• wherein the one or more genetic variations comprise chr8:61654298 T>A, chr2:163136505 C>G, chr22:23917192 G>T, chr20:3846397 C>T, chr16:81942175 A>G, chr8:145154222 G>A, chr11:67818269 G>A, chr8:145154824 A>C, chr22:23915745 G>A, chr20:3843027 C>A, or any combinations thereof, and wherein chromosome positions of the one or more genetic variations are defined with respect to UCSC hg19.