I find it a bit concerning when articles like this assume that all 7 billion people have had the resources to get the kind of check ups that would have their samples in a global database of genetic mutations.
Well, at least for the kind of de novo mutation that the article is talking about, it's vanishingly unlikely that anyone has the same exact mutation. It looks at a cursory glance like the gene in question is ~180k base pairs long, so the idea that someone else also has this (potentially fatal) truncation in the same spot is really unlikely. Especially if the mutation would be fatal if it were misplaced a bit.
It's also a bit of misdirection, since the net effect is "half of your PLCG2 expression is turned off", which is probably also represented in that 60 similar patients the article talks about. So it's technically true but almost certainly something that other people have as far as a "half knockout of gene XYZ".
I find it a bit concerning when articles like this assume that all 7 billion people have had the resources to get the kind of check ups that would have their samples in a global database of genetic mutations.