• Question: how does illnesses such as cancer follow through to generations in genes ?

    Asked by whaishandhan to Anil, Blanka, Cees, Emma, Mike on 4 Jul 2012. This question was also asked by whkacandcoco.
    • Photo: Emma Trantham

      Emma Trantham answered on 4 Jul 2012:

      OK this is a difficult one!

      I’m going to do my best to describe it but if at any point I don’t make sense/confuse you please ask about it at the bottom.

      The cells in our body grow and divide at certain times, the rest of the time they are resting. Cancer cells keep on growing and dividing – they don’t stop.

      The majority of cancers are not passed down through our genes but some are. The way this works is that say person A has a defect (problem) in their DNA. This defect affects a certain type of cell (say for example a cell in their breast) and makes these cells more likely to become cancerous (that is more likely to ignore the signals that tell them to stop dividing).

      When person A has a baby this defect/problem might be passed down into the baby (because we are all made up of the DNA of both our mum and our dad). The cancer will probably not show (if it does show) until the baby grows up.

      But as I said, only a tiny proportion of cancers are inherited at all and just because a person does have a cancer that can be passed down the generations that doesn’t necessarily mean it will be.

      I don’t know if Blanka can add any more to this.

      Does it answer your question?

    • Photo: Michael Cook

      Michael Cook answered on 4 Jul 2012:

      I thought I knew how this worked but had no idea how to describe it! Emma’s answer is great and taught me quite a bit.

    • Photo: Blanka Sengerova

      Blanka Sengerova answered on 4 Jul 2012:

      I think Emma’s pretty much covered the basics. I will just add that often what is inherited is the susceptibility to cancer, not the cancer itself. You have two copies of all of your genes (one from Mum and one from Dad) and sometimes if one of them isn’t functioning (if it codes for something like a protein involved in the repair of DNA) you may be able to survive long enough with only one copy but your cells’ DNA (genetic material) is more likely to become damaged and lead to cancer. You still need some environmental factors for these cancers to occur so you may often be able to produce offspring before the cancer manifests itself and you pass on this defect to them.

      Does that make sense?