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MRC Harwell at the british science festival

We travelled to Birmingham to run our ‘DNA Diagnosis’ workshop at the British Science Festival on Thursday 11th September, which focused on the tricky topic of genetic testing.

The British Science Festival is one of the largest science festivals in Europe, and every year it attracts a host of spectacular science shows, deep discussions and thought-provoking talks. MRC Harwell’s workshop was designed to give sixth-form and college students an insight into medical research by asking them to use DNA samples to make their diagnosis.

We presented the students with the scenario of a family where the father had Huntington’s disease, a devastating genetic condition caused by an autosomal dominant mutation within the HTT gene. The most common symptom is Huntington’s chorea, uncontrolled involuntary writhing movements caused by neurodegeneration in the brain, but can also be accompanied by changes in mood, coordination and gait. Genetic testing is currently available at various stages, including before having children, as part of a selection process during IVF, during pregnancy and after the child is born. It raises a multitude of ethical questions, and anyone who undergoes such testing must first receive genetic counselling.

As the mutation within the HTT gene introduces more CAG (cytosine-adenine-guanine) repeats, the mutant allele is longer than the healthy allele. Because of this, the mutant HTT allele can be detected by separating the gene DNA based on its size. This is done using two very common laboratory techniques; polymerase chain reaction (PCR) and gel electrophoresis.

So we set the students a challenge – can you use these two techniques to work out which of the children in the family have inherited their Dad’s mutant HTT gene? We gave them an instruction sheet, the DNA and reagents, and they got stuck in. While a few had been lucky enough to have done similar experiments on work experience, for many of the students it was the first time they had ever picked up a pipette. It gave them a great introduction to life in a lab, and we made our way around the tables to ask them about their career aspirations and offer a little advice.

Once each group had loaded their gel, we set it running for 15 minutes. While they waited, we struck up a discussion about the ethics of genetic testing – would they really want to know if they had the mutant HTT gene, considering that we have yet to find a cure? At what age can a child decide to get tested? Can parents make the decision on their child’s behalf? Is it right to select embryos for IVF or abort an affected foetus? Of course, these are tough questions and we weren’t expecting any clear-cut answers, but it got the students thinking about this whole ethical maze.

However, they could answer one question – which family members had Huntington’s disease? One band meant they just had the healthy allele, whereas two bands meant they had a copy of the mutant version and would go on to develop the condition later in life, just like their dad. The results were as expected, with the mutant allele present in two of the four children’s DNA. Thankfully, these samples weren’t taken from real patients, but it could just as easily have been a true diagnosis. Would you want to know?

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