Furthermore, a PubMed search did not reveal any case reports of PML in patients with underlying diseases such as eosinophilic granulomatosis with polyangiitis (previously known as Churg–Strauss syndrome), pemphigus foliaceus, polymyalgia rheumatica, or myelin oligodendrocyte glycoprotein antibody-associated disease. The gene discussed is OMG; the disease is progressive multifocal leukoencephalopathy.