One of the most important medical discoveries in history is all down to serendipity. Today comes news of another discovery that happened, not quite "by accident" but was certainly unintended.
Scientists at Edinburgh University, backed by the Medical Research Council have been studying a rare childhood disease known as Aicardi-Goutières syndrome. It is a genetic disease that can be fatal in the first years of life.
The surprise is that the mechanism behind this disease turns out to be amazingly common and could play an important part in cancer.
When cells divide they have to copy all their genetic instructions - their DNA. They do this by using "messenger boys" called RNA. The fault behind the rare syndrome is that bits of this RNA get caught up in the mechanism and get captured in the new DNA - which doesn't function properly. Normally, the body has a chemical fix for this problem which cleans up the RNA.
Without this fix every cell accumulates a million faults every time it divides - and that's what happens in the rare syndrome. But that fault could also be implicated in other diseases - like cancer. That's the excitement.
Dr Andrew Jackson, who led the research, said: “The most amazing thing is that by working to understand a rare genetic disease, we’ve uncovered the most common fault in DNA replication by far, which we didn't even start out looking for!"