Genes may help to explain why kidney stones come back
New research published today and co-funded by us has revealed 20 genetic areas linked to kidney stone disease, seven of which have never been linked to the condition before.
As well pinning down which genetic areas are linked to kidney stones , Dr Sarah Howles at the University of Oxford has identified that two of these areas are close to genes that control how our bodies use the ‘sunshine vitamin’ - vitamin D - and calcium.
We’d need more research to prove it, but it suggests some people with kidney stones who have a particular genetic makeup should be cautious when using vitamin D supplements.
What are kidney stones?
Kidney stones are common and affect around one in ten people. They're small crystals made from salts and minerals that form inside your kidney - some are as small as a grain of sand but others can be as large as a few centimetres.
If a kidney stone moves down your ureter - the tube that takes the urine from your kidney down to your bladder - it can be a very painful experience! Once in your bladder, a kidney stone can make it feel like you need to wee all of the time and make weeing itself especially uncomfortable.
If this wasn't enough, people who have kidney stones have more chance of developing chronic kidney disease (CKD) in the future.
The exact cause of kidney stones is hard to pin down – as it's a combination of many factors. They're much more likely to form if you aren't drinking enough fluids or suffer from some medical conditions. We all naturally concentrate our urine overnight, so this is probably the time when most stones form and grow. We can also observe that kidney stones often run in families - that is, you're more likely to develop kidney stone disease if a direct relative has experienced them in the past. Other than that, what causes kidney stones is a mystery.
Hunting for stones in genes
With family history being one of the few clear factors causing kidney stones, Dr Howles and her team wanted to work out what the common genetic factors putting people at risk of kidney stones were.
She set out to examine the genetic make-up, or genome of 12,123 people who have previously had kidney stones and 416,928 healthy people. Your genome refers to whole set of genes, and you have around 20,000, so this was a huge task!
To do this, the researchers carried out a genome-wide association study, or GWAS. These studies look at complete genomes to identify differences or similarities between people with a particular disease and healthy people. GWAS studies enable scientists to start to locate specific areas of the genome that might contribute to someone’s risk of developing that disease - in this case, kidney stones. And the next step would be to identify which genes are in those areas and what is happening when faults creep in.
In the past, GWAS studies have helped to highlight variations in particular genes that relate to conditions, including diabetes, heart conditions, Parkinson’s disease, and Crohn’s disease.
In this work published in Nature Communications, Dr Howles has found 20 areas of the genome associated with kidney stones - seven of which have never been identified before to be linked to kidney stones.
Sunshine vitamin and kidney disease
One of those areas on the genome is linked to how your body breaks down vitamin D. You need vitamin D to absorb any calcium you take in from your food, which is essential for healthy bones, teeth and muscle.
The genes that the GWAS picked out were heavily involved in how the kidneys work and how your body balances the amount of calcium. After looking at the results in more detail, it seems that vitamin D breakdown may play a role in kidney stone formation.
So what does this mean for me?
For most of us, taking vitamin D supplements is fine, and indeed many of us are told to take vitamin D as we spend more time inside than out.
But this research shows that a ‘one message fits all’ approach may not be right here. In a specific group of people with kidney stones, it might be a bit more complicated, and more research is needed to prove how vitamin D metabolism influences how kidney stones form.
Get our e-newsletter
Stay up to date with our kidney research news, events and ways to get involved.