Genetic testing

Has anyone had a genetic test that tells yes or no to autoimmune disease? It does not diagnose if positive and am I understanding correctly this test is a real thing? I ask because I was told I should schedule an appointment at Jewish National in Denver and have genetic testing like this along with a list of other specialists to see by an Immunologist in my area. I have not started the process yet and in the meantime for the past 2 years have been on IVIG for Hypogammaglobulinemia my IgG level now in the 800’s but IgA which was normal now below range which may not mean much, depends on which articles I read. I just had an increase to 30 grams with IVIG as provider had been concerned about kidney levels but feels numbers are stable enough now. I must say I had slight improvement with lower dose I was on in regards to infections but weakness has not improved so going from being extremely active to where I am now (over a 12-15 year period) which has worsened in the last 8 or so months has me wondering about any diagnosis which the Immunologist I saw isn’t sure I have so the recommendation to have further testing then get back to him. Anyway my longwinded way to ask about anybody’s experience or where they went for testing etc. Thank you.