West syndrome may arise from idiopathic, symptomatic, or cryptogenic causes. Cases of epilepsy have been historically divided into three different groups&colon; symptomatic, cryptogenic, and unknown. This form is known as cryptogenic occult infection. The majority of cryptogenic cirrhosis is believed to be due to NASH. Until recently, patients with PFO and cryptogenic stroke were treated with antiplatelet therapy only. Mutations in this gene have been linked to cryptogenic cirrhosis. Occipital lobe epilepsies are etiologically idiopathic, symptomatic, or cryptogenic. It is not related to cryptogenic organizing pneumonia, previously known as bronchiolitis obliterans organizing pneumonia. The cryptogenic group is often considered idiopathic while referred to as "cryptogenic". As such, it forms a subset of cryptogenic stroke, which is part of the TOAST-classification. The name cryptogenic obliterative (constrictive) bronchiolitis is used when a cause is unknown.