• Question: Depending on the genetic material, why do some people react differently to different treatments and/or medicines?

    Asked by kateperry01 to Reka, Tomas, Laura, Judith, Hannah, Gemma, Emma on 8 Jan 2019. This question was also asked by elliestobirski.
    • Photo: Reka Nagy

      Reka Nagy answered on 8 Jan 2019:

      That’s because while we are all humans, our DNA is not 100% identical! The small differences in our DNA make us who we are, and also influence how likely we are to respond (or not respond, or respond badly) to some treatments or medicines.

      For example, one of the treatments of nonsmall cell lung cancer is the use of chemotherapy drugs gefitinib and erlotinib. These drugs target the gene EGFR (which stands for Epidermal Growth Factor Receptor), but they are only efficient in patients whose tumours have specific genetic variants within their EGFR genes.

      Another example, that doesn’t relate to cancer (since cancer cell’s DNA can mutate and change), is neonatal diabetes mellitus – that is, infants who develop diabetes soon after birth. Researchers have found that these patients often have a mutation in their KCNJ11 gene which make this gene turn on when it shouldn’t. When this gene is turned on, it prevents insulin from being secreted, and without insulin, you end up with high blood sugar levels. Previously, these patients were just given insulin, but after this mutation was found, scientist realised that they could instead inhibit the activation of KCNJ11 – and drugs that do this already existed, so it was an easy switched that works really well!

      The arm of genetics that is trying to figure out which subpopulations might respond better to which drugs is called precision medicine, or stratified medicine!