Over the past year, the SciWhys column has explored a number of different topics, from our immune system to plants, from viruses to DNA. But why is an understanding of topics such as these so important? In short, using science to understand our world can help to improve our lives. In my last post and in this one, I want to illustrate this point with an example of how progress in science is providing hope for the future for one family, and many others like them.
By Jonathan Crowe
In my last post, I introduced you to Carys, a young girl living with the effects of Rett syndrome. Thanks to scientific research, we now understand quite a lot about why Rett syndrome occurs – what is happening among the molecules within our cells to mean that some cells don’t behave as they should. Simply knowing about something is one thing, though; making constructive use of this knowledge is another thing entirely. During this post I hope to show you how our understanding of what causes Rett syndrome is being translated into the potential for its treatment – a cure for Carys, and the other young girls like her.
In my previous post I mentioned how Rett syndrome is caused by a faulty gene called MECP2 that affects the proper function of brain cells. However, the syndrome doesn’t actually kill the cells (unlike neurodegenerative diseases that do cause cells to die). Instead, the cells affected by Rett syndrome just function improperly. This leads us to an intriguing question: if the faulty gene that causes the syndrome could be ‘fixed’ somehow, would the cells start to behave properly? In other words, could the debilitating symptoms associated with Rett syndrome be relieved?
Obviously, researchers can’t simply play around with humans and their genes to answer questions such as these. Instead, researchers have studied Rett syndrome by using “mouse models.” But what does this mean? In short, mice and humans have biological similarities that allow the mouse to act as a proxy – a model – for a human. How can this be? Well, even though the huge variety of creatures that populate the earth look very different to a casual observer, they’re not all that different when considered at the level of their genomes. In fact, around 85% of the human and mouse genomes are the same.
Now, if the biological information – the information stored in these genomes – is similar, the outcome of using this information will also be similar. If we start out with two similar recipes, the foods we prepare from them will also be very similar. Likewise, if two creatures have similar genes, their bodies will work in broadly similar ways, using similar proteins and other molecules. (It is the bits of the mouse and human genomes that aren’t the same that make mice and humans different.)
In essence, the mouse Mecp2 gene is to all intents and purposes the same as the human MECP2 gene, and has the same function in both mice and humans. Equally, if this gene malfunctions, the consequences are the same in both mouse and human: a mouse with a mutation in its Mecp2 gene exhibits symptoms that are very like a human with a mutation in the same gene – that is, someone with Rett syndrome. In short, mice with a Mecp2 gene mutation are a model for humans with the same mutation.
With all this in mind, if we can learn how to overcome the effects of the Mecp2 mutation in the mouse, we might gain valuable insights into how we can overcome the equivalent effects in humans.
And this is wh