Is nasuea a symptom of fatal familia insomnia or sporadic fatal insomnia?

Nausea. Nausea can come along with many types of conditions. However, it's not a symptom leading to the diagnosis of any kind of fatal insomnia [an exceedingly rare condition anyway]. Here's a site with all kinds of information about nausea: http://www.Emedicinehealth.Com/vomiting_and_nausea/article_em.Htm.
Nausea & SFI. As rare as sfi & as many as there are causes for nausea, your chances of having sfi are slim to none.