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Today is known worldwide as World Kidney Day. Our kidneys are amazing organs which provide humans with vital functions to keep us healthy but are often forgotten about when compared to the heart and lungs. The aim of World Kidney Day is to raise awareness of kidneys, and provide the public with information on how to keep our kidneys healthy.

Currently, over 1 million people in the UK have kidney disease they aren't even aware of. Unfortunately, known kidney diseases more often than not lead to the need for kidney transplantation. There are almost 5000 patients waiting on a kidney transplant, of that 5000 only 72% of patients will ever receive one.

Our kidneys have a number of roles within the body including the filtration and cleaning of our blood, controlling the body’s fluid content and regulating our blood pressure. Every time our heart beats, 25% of our blood flows through the kidneys - that’s higher than the blood flow to the brain. Filtration is achieved through special kidney structures called nephrons, there are approximately 1.15 million of them throughout the kidneys - stretched out end to end and they would cover over 8km in length!

However, the accurate and useful diagnosis of kidney disease is fraught with challenges. Many diagnoses describe the appearance of the disease without revealing knowledge of the cause. This type of diagnosis offers limited use in directing patient treatment.

One example is the kidney disease Alport syndrome (AS), which was first described in 1927. For more than 60 years after its discovery, the cause of AS remained unknown. It was diagnosed by blood being found in the urine, most frequently in teenage males. This was accompanied by progressive hearing loss and characteristic microscopic appearance of the kidney cells which filter our blood. Fast forward to 1990 and the genetic cause, mutations in COL4A5 located on the X chromosome, was discovered. This enabled researchers to investigate how this gene functions normally and how alterations in the gene product cause pathology. Furthermore, this also revealed the reason males are more often impacted. The X chromosome is sex linked; males have one X chromosome whereas females have two. This means that males have one copy of COL4A5 and a mutation here can lead to Alport syndrome, whereas a female would require mutations to both of their COL4A5 genes. Subsequent investigation revealed that mutations in related genes, COL4A3 and COL4A4 located on chromosome 2, also cause AS but not in a sex-linked fashion.

Although primarily a disease that affects kidney function, the eyes and ears are frequently impacted in AS. This is because the same genes required within the kidney filters (COL4A3, COL4A4 and COL4A5) are required to support the specialised sound-sensing hair cells in the ear and the cornea in the eye.

Now, due to the contribution of many researchers, AS is the best-characterised genetic kidney disease. However, despite this fact, there are still no targeted therapies. Currently, to prolong the survival of the kidney, patients receive angiotensin-converting enzyme inhibitors and angiotensin receptor blockers to reduce blood pressure. The kidneys work extremely hard as they are exposed to 25% of the cardiac output; therefore, reductions in blood pressure help to protect the kidneys from force.

It is apparent that more research into AS is still required and to support this communities, patient families, physicians, geneticists, researchers, industries, and funding organisations from around the world meet annually at workshops to investigate new avenues of AS research. I have been fortunate enough to attend and interact with this community at meetings in Göttingen, Glasgow and London. There is much optimism with large numbers of pharmaceutical companies taking serious interest in AS. The collaboration between clinicians, patients and researchers is key to accelerating the discovery of new therapeutic approaches for patients with this kidney disease.

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