Re: Lupus in the family
Hayley, hi & welcome! As klbk posted, lupus is a multi-faceted diagnosis, based on more than a single test or genetic history. There's a "sticky post" ( = permanent info post) at the top of the thread list with the accepted diagnostic criteria. You typically** must meet at least 4 of the 11 at some time (meaning not necessarily all at once), to be Dx'ed with systemic lupus. Think of checking off each criterion you've met, in indelible ink.
** I used the word "typically" because I've read that people are occasionally Dx'ed based on fewer than 4 criteria. The criteria met are no doubt the HUGE ones (I think). As klbk wrote, anti-ds-DNA surely is a "biggie", as it (and anti-Sm) are viewed as exclusive to lupus. Either of those coupled with, say, a high ANA &/or protein in the urine would probably raise a huge red flag to a doctor, even when 4 criteria haven't yet been met.
More thoughts: (1) ANA is only a threshold test; and it's positive in multiple diseases & conditions (not just lupus), or even due to a family tendency, a passing virus, aging, etc. (2) Lupus is not considered heritable, strictly speaking. That said, autoimmunes can cluster somewhat in families. e.g., my sister has a thyroid disease; I have lupus. (3) Some people have some mild "positives" in the specialized bloodwork yet are otherwise asymptomatic, meaning have no "clinical symptoms" like fatigue, joint pain, etc. I think drs. tend to monitor, to see what (if anything) happens next.
Hardcover books written by rheuamtologists discuss SLE in great detail. I don't know names of Australian rheumie/authors (sorry). Here are a few I do know of: Dr. Graham Hughes (U.K.); Dr. Daniel Wallace &/or Dr. Robert Lahita (both American).
If your sister remembers which TV station she saw the show on, maybe you two could contact the station for specifics? Let us know how you all are doing, when you can. Sending best wishes, Vee