Apart from diet, daily water consumption and lifestyle choices, one’s genes also play a crucial role when it comes to the risk of developing certain kidney diseases.
Doctors point out that in some cases multiple family members get diagnosed with the same genetic renal disorder. “In cases like these, genetic testing will help,” says Dr Avinash Ignatius, a Pune-based nephrologist and transplant physician. Genetic testing also helps in the management and treatment of certain renal disorders.
In the case of a 57-year-old man from the US who presented with blood and protein in the urine, genetic testing helped him avoid a form of treatment that would have been ineffective. His kidney biopsy showed that he suffered from focal segmental glomerulosclerosis (FSGS), a type of disease that attacks the kidney’s filtration system.
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“The man was referred for steroid therapy, but he wanted a second opinion,” Dr Ali G Gharavi, professor of medicine & chief, Division of Nephrology, Columbia University, New York City, said while presenting the relevant case study at a 2020 webinar organised by the Kidney Disease Improving Global Outcomes, a global non-profit foundation dedicated to improving the care and outcomes of patients with kidney disease worldwide.
Dr Gharavi said that the man’s biopsy results revealed secondary causes behind the FSGS diagnosis.
The doctors then decided to perform a gene sequencing test which revealed that the man actually suffered from a dominant form of Alport syndrome (a genetic disorder that affects the kidneys, ears and eyes). “In this case, we had to tell him that steroids would be of no help for him. We referred him to a new clinical trial designed for those with Alport syndrome,” said Dr Gharavi.
The doctors advised the man to also screen his family members who may be at risk for the disease and start selecting those who would be most suitable for a kidney donation in case his condition progressed to kidney failure.
“There are some kidney disorders in which the primary mode of treatment is giving immunosuppressants [and] steroids for a long time,” says Dr Ignatius. “Doing genetic testing early can help identify such patients who may not benefit from immunosuppressants. This will reduce their unnecessary exposure to strong immunosuppressant medicines.”
Dr Ignatius says that a genetic test will be able to tell beforehand if a person is carrying a particular gene that puts them at risk of developing a kidney disease and can also confirm the diagnosis.
What kidney diseases can genetic testing largely identify?
Dr Parimal Das, professor, Centre for Genetic Disorders, Institute of Science, Banaras Hindu University, Uttar Pradesh, says that genetic diagnosis can provide new clinical insights in a significant proportion of cases and is especially important in the case of chronic kidney disease (CKD).
“Studies have suggested that approximately 70% of paediatric cases and 10% of adult cases of CKD, and 30% of paediatric cases and 10% of adult cases of end-stage kidney disease may have an identifiable genetic cause,” he says.
Dr Das says genetic tests can identify the underlying causes of several other inherited renal diseases such as:
- Polycystic kidney disease: A type of disease in which numerous cysts develop in the kidney
- Alport syndrome
- Congenital nephrotic syndrome: A rare disorder in which there is excessive protein loss in the urine, leading to fluid accumulation and swelling in different parts of the body
- Nephronophthisis: leads to kidney failure in childhood or adolescence
- Fabry disease: caused by the build-up of fat in the body’s cells.
When to conduct genetic testing for renal disorders
Dr Das says that the European Society of Human Genetics recommends that genetic testing should be performed when there is a strong suspicion that there is a genetic cause to the renal disorder, such as a family history of renal disorders. It is also recommended during prenatal diagnostic tests for someone who comes from a family with a known genetic risk for a specific renal disorder.
But nephrologists say things are a little different in clinical nephrology.
“Genetic testing is usually done when the person with the kidney disease fails to respond to the first and second line of treatments,” says Dr Ignatius. “Once an underlying genetic disorder is confirmed, the treatment, mostly involving the administration of immunosuppressants and steroids, will not have many benefits. The best line of treatment in this case is preserving the kidney function as much as possible with standard drugs like ace inhibitors (blood pressure-lowering medication). General management features can be focused on, but unnecessary medications can be avoided.”
Challenges to genetic testing for renal disorders
Dr Das says that there are many different genetic mutations that can cause renal disorders and not all of them are well understood. “In some cases, the specific genetic mutation may be difficult to identify, which can make it challenging to perform accurate genetic testing,” he says.
Dr Das adds that quite often the symptoms of kidney diseases can highly differ from one family member to the other. Interpreting genetic test results can also be challenging, particularly if the results are uncertain, he says. “In some cases, the results may be difficult to interpret and may require additional testing or clinical evaluation,” he adds.
Dr Das says that genetic counselling is also an essential component of the genetic testing process and should be provided to help patients and their families understand:
- the implications of test results
- the risk of passing the disorder to future generations and
- the available treatment options.
Takeaways
- Your genes play a role when it comes to the risk of developing certain kidney diseases.
- Genetic testing can help in the diagnosis, management and treatment of several inherited renal disorders.
