This was a question that came up again on a forum, Turner Syndrome is on its own by no means life threatening, as you have discovered from other pages I have explained that generally a very normal healthy life is lead.
The only thing I would highlight is that some butterflies have heart conditions as part of Turners, now this isn’t too major and alot of us suffer minimal effect from this. However, I have known a number of butterflies that have now passed as a result of surgery complications or as a result of sudden heart problems that have at times gone undetected or progressed.
I am also aware of a number of butterfiles that have died before birth, now again Turners alone is not life threatening the ones that I hear of passing at this point are suffering alot of problems such as major swelling or other defects alongside not solely Turners.