Genetic Evaluation of Natalizumab-Treated Patients With Progressive Multifocal Leukoencephalopathy

Genetic Evaluation of Natalizumab-Treated Patients With Progressive Multifocal Leukoencephalopathy

The purpose of this study is to explore host genetic mutations which may render individual subjects more susceptible (or resistant) to developing Progressive Multifocal Leukoencephalopathy (PML). Samples will also be collected to determine Deoxyribonucleic Acid (DNA) sequence of JC Virus (JCV). Analysis of the JC Virus (JCV) genome may provide information about viral genotypes that may be associated with higher pathogenicity, and help to identify individuals who may be at higher risk of developing Progressive Multifocal Leukoencephalopathy (PML) due to chronic infection with a more pathogenic variant of JC Virus (JCV).

Deoxyribonucleic acid (DNA) will be analyzed from natalizumab-treated subjects who develop Progressive Multifocal Leukoencephalopathy (PML). The genetic analysis of the subjects will directly seek mutations that could identify subjects at risk.

Key Inclusion Criteria:

• Subjects who have confirmed PML while on treatment with Natalizumab

NOTE: Other protocol defined Inclusion/ Exclusion criteria may apply.