My favorite is "idiopathic", but "cryptogenic" is also correct.

Here are some words with the prefix crypto. Cryptanalytics, cryptoanarchy, cryptobranchiate, cryptolect, cryptology, cryptonym, cryptomaterial, cryptomodule, cryptosystem, cryptocurrency, cryptocustodian, cryptocyanin, cryptosecurity, and cryptogenic.

The medical terminology combining form crypto- means hidden or secret. It is commonly used in words such as cryptorchidism (undescended testicle) and cryptogenic (of unknown cause).

there are two causes which i am certain to cause ground glass infiltrates, ARDS (acute respiratory distress syndrome) and a much rarer condition called Cryptogenic organising pneumonia.. ground glass infiltrates refers to involvement of both the alveoli and the pulmonary interstitium which occurs in both the conditions resulting in homogenous density film on a plain XR of the chest...

Autism is not a life threatening (or life-limiting) condition, and therefore has no impact upon a person's lifespan. Epilepsy can be at times life threatening and is likely to be life-limiting - however to what extend depends a lot on how well controlled the epilepsy is. According to epilepsy.com, if the person is otherwise relatively healthy epilepsy should not shorten their lifespan. Which is probably true, however (to me) it gives the slightly misleading impression that people can do things to help them become "relatively healthy", whereas what they are actually witnessing are epileptics who happen to be randomly lucky in their health.

Gaitatzis et al in their study of "Life expectancy in people with newly diagnosed epilepsy " (pubmed 15371287) conclude that "Reduction in life expectancy can be up to 2 years for people with a diagnosis of idiopathic/cryptogenic epilepsy, and the reduction can be up to 10 years in people with symptomatic epilepsy. Reductions in life expectancy are highest at the time of diagnosis and diminish with time". The fact that reduction in life expectancy reduces the further away you get from diagnoses indicates that epilepsy which is treated and well controlled poses much fewer issues than un-managed epilepsy.