• Question: What type of thing are you actually looking for in the genes?

    Asked by to Bethany on 13 Jun 2014. This question was also asked by .
    • Photo: Bethany Dearlove

      Bethany Dearlove answered on 13 Jun 2014:

      This is a really great question! It comes down to why we’ve sequenced a particular bug. If we’re just interested in tracking how a disease is spreading, we’re looking for genes that are overall very similar, but show mutations that might have accumulated over the transmission chain. For example, if we had:
      Patient1: ATGGGAC
      Patient2: ATGAGAC
      Patient3: ATGAGAT
      Patient4: GTCCATT
      we’d say that Patient2 most likely got it from Patient1 (G mutated to A), and Patient3 got it from Patient2 (G to A like Patient2, and then an additional C to T). However, Patient4 is completely different, so probably not in the transmission chain at all, and came into the hospital infected from a completely different source.

      We can also use genes to tell us about the disease itself, for example, whether it’s a potentially dangerous strain or not, and how to treat it. One of the things we’re doing in bacteria is to identify the genes that give antibiotic resistance. That way, rather than having to grow the bacteria in the lab with difference sorts of antibiotics and seeing which ones work (and which ones don’t), we can use the sequence to identify which genes it has – and therefore which are most likely to work (or not). When sequencing becomes standard in hospitals, this will take ‘personalised’ and ‘targeted’ medicine to a whole new level!

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