<<Disclaimer: Verify this information before applying it to your situation.>>

this is for those with older relatives who are *not* diagnosed coeliac.

ataxia involves dizziness, unsteadiness and so forth.  a typical
cause is a minor stroke.  those for whom no cause can be found
are potentially undiagnosed coeliacs as this article discusses:

    Coeliac disease in patients with cerebellar ataxia of unknown
        origin.
    Luostarinen LK, Collin PO, Peraaho MJ, Maki MJ, and Pirttila
        TA
    Ann Med 2001 Sep 33(6): p. 445-9

http://bmj.com/cgi/external_ref?access_num=11585106&link_type=MED

if you know anyone who meets this description, they may wish to
participate in clinical studies going on now:

 Gluten-Free Diet in Patients with Gluten Sensitivity and Cerebellar
 Ataxia  This study is currently recruiting patients.

 http://clinicaltrials.gov/show/NCT00006492
 http://clinicalstudies.info.nih.gov/detail/A_2001-N-0003.html