Chia seeds are from the Salvia hispanica plant. This plant is in the Lamiaceae family which contains lots of edible herbs such as mint and sage.
With the rise of veganism in Western countries the use of chia seeds has increased as they are an excellent replacement for eggs as they act as a thickening agent.
Chia seeds contain 7S and 11S seed storage proteins, which are protein found in lots of other nuts and seeds. There is however very limited information or clinical evidence on cross reactivity to show that these seeds should be avoided by nut and seed allergy sufferers.
There are only 2 case studies of chia seed causing severe allergic reaction, which may indicate the likelihood that cross reactivity between chia seeds and other seeds and nuts is actually very low.
I have put together some more comprehensive resources at http://www.allergyresources.co.uk/Chia.php
The allergy resources page for chia seed allergy covers the key allergens, which allergic syndromes are linked to this allergy and other foods which are commonly cross reactive with chia seed allergy.
There is also regularly updated links to useful websites specifically for cat allergies and the latest research papers on the topic.
If you have multiple allergies and are interested in how they are linked or want to find out more about food allergies outside the usual top 14 then you can follow me on Facebook or Twitter, where I share a food allergy card every day of the week.