A new way of diagnosing Alport disease, using next generation sequencing, has the potential to identify patients at early disease stages — a practice that could delay the onset of end-stage kidney disease and improve life expectancy.
The study, “Efficient Targeted Next Generation Sequencing-Based Workflow for Differential Diagnosis of Alport-Related Disorders,” published in the journal PLOS ONE, demonstrates that the new method is an easy to use, fast, and economic approach to accurately set an early Alport diagnosis — or to exclude its presence in patient’s relatives.
Although Alport patients often start leaking blood into the urine during the first years of life, other symptoms tend to appear later. The similarity of Alport to familial benign haematuria, also called thin basement membrane disease, makes a diagnosis complicated.
Neither physical examination nor an examination of tissue samples are valuable diagnostic aids early in the disease. Yet, an early diagnosis could substantially improve outcomes, as studies show that early treatment can delay or even prevent progression to end-stage kidney disease.
Researchers at the University of Szeged in Hungary argued that the only means of early diagnosis is the identification of mutations in the Alport-causing genes COL4A3, A4, and A5.
They recruited 14 families in which Alport or thin basement membrane disease was suspected, and three additional patients without family ties. The study also included 66 controls to get a picture of normal variation in the gene sequences, which do not contribute to disease.
Next generation sequencing analysis revealed 37 genetic variations among the patients. Of them, 21 were previously known variations not contributing to disease, and four were previously known disease-causing mutations.
In addition, the team identified 14 new mutations that caused Alport: five in the COL4A3 gene, three in COL4A4, and six in COL4A5. Additional sequencing and analyses confirmed that the mutations caused Alport disease in the affected individuals.
The method also allowed the team to categorize the three unrelated individuals as X-linked Alport disease and thin basement membrane disease.
Researchers described their workflow in detail, allowing other researchers or clinicians to adopt the same approach in distinguishing between patients with Alport disease and the milder disease, not likely to cause kidney damage.