How to do optimal genetic testing in patients who may have hereditary kidney disease? How useful is it to analyse different types of genetic variants? PhD candidate Laura Claus, a researcher in Albertien van Eerde’s nephrogenetics group (UMC Utrecht), found that there is indeed added value in unravelling this. She published about it in the scientific journal Kidney International Reports.
Kidneys have many important tasks in a body. If your kidneys don’t work properly, it affects your whole body. In the Netherlands, 1.7 million people suffer from kidney damage. Eventually, kidney damage leads to end-stage kidney failure in a proportion of patients. When this happens the kidney function is so poor that a machine has to filter the blood (dialysis) or the patient needs a new kidney (kidney transplant). Kidney damage in older adults is often caused by high blood pressure or diabetes. But kidney damage can also occur due to hereditary kidney disease. Especially in children, this is usually the case. A hereditary disease means that the kidney disease is caused by a defect in your DNA. The disease might then be passed on to a child. Genetic testing can reveal whether you have hereditary kidney disease.
23 per cent of the 2432 kidney patients who received genetic testing at the UMC Utrecht over the past eight years were found to have confirmed hereditary kidney disease. Within this patient group, 10 per cent of these people had the hereditary kidney disease revealed by a genetic test involving ‘CNV analysis’. Copy Number Variant (CNV) analysis is used to check whether pieces of DNA are missing or duplicated. Previously, a separate test had to be requested for this, but since 2021, this has been a standard part of the regular genetic testing that looks at DNA mutations. This makes genetic testing more cost-efficient. This approach is not yet common practice internationally.
This study shows that the Utrecht approach is useful for others. ‘Genetic testing is covered by basic health insurance in the Netherlands and nephrologists can request such a test from us. With the current test, we pick up nearly all CNVs without the need for an additional test,’ says Laura Claus. ‘Regularly, such a test can prevent a nephrologist from having to do other invasive tests, which serves the patient’s best interest.’
Identifying a genetic cause of a disease can be very important for kidney patients and their families for several reasons. For example, it can lead to a diagnosis, it can influence treatment and it can provide information about the expected course of disease. One can also be informed about the risk of the same kidney disease for family members. Because not all inherited kidney diseases are inherited in the same way, the probability of passing on the disease may also differ. So, it is important to discuss the options available when filling out a wish for children.
If people know where their kidney disease comes from, it also helps in making decisions about kidney donation. If you donate a kidney, it is important that the remaining kidney remains healthy. Does a hereditary kidney disease run in the family? Then it is important that people realize that you can only donate a kidney once. They should therefore be aware of when and to whom they want to donate a kidney.
‘Genetics is finding out whether the condition a patient is experiencing is related to an inherited disease. That can be a puzzle,’ says Laura. ‘Besides, it is a medical specialty in which I have valuable patient contact as a doctor. It helps people when they better understand where their kidney disease comes from. And it also makes them look differently at certain life questions. For example, I counsel patients who wish to have children. Passing on hereditary kidney disease to the next generation is something they can be very concerned about. By discussing the possibilities in that area with them, I can really do something for them as a clinical geneticist in training.’
