Tysabri: Four More Cases of PML

Biogen Idec Inc (BIIB.O) said on Wednesday that four more patients taking its multiple sclerosis drug Tysabri had developed a potentially deadly brain infection known as PML in November, bringing the total to 28.

The biotech company said it will release the number for December soon.

Progressive multifocal leukoencephalopathy (PML), also known as progressive multifocal leukoencephalitis, is a rare and usually fatal viral disease that is characterized by progressive damage (-pathy) or inflammation of the white matter (leuko-) of the brain (-encephalo-) at multiple locations (multifocal).(Via Wiki



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