idiopathic

Joel noted that the condition is idiopathic, meaning no one knows the cause.

Hussain died Sunday afternoon in San Francisco of idiopathic pulmonary fibrosis, a chronic lung disease, his family said in a statement.

The Indian classical music icon died of idiopathic pulmonary fibrosis, a lung disease, at a hospital in San Francisco, his family said in a statement.

The radio legend was diagnosed with idiopathic pulmonary fibrosis, a severe respiratory illness that can make breathing very difficult.

Further serious health problems followed, including being diagnosed with idiopathic intracranial hypertension - a build-up of pressure around the brain - and fibromyalgia, a chronic condition causing widespread pain throughout the body.