Alport Disease May Be Identified by More Severe Symptoms in Children With Thin Basement Membrane Disease

As a small proportion of children, initially diagnosed with thin basement membrane disease, eventually receive an Alport disease diagnosis, it is crucial to continue to monitor all children with thin basement membranes, performing genetic and tissue analyses as often as possible.

The study, “The Transition from Thin Basement Membranes to Typical Alport Syndrome Morphology in Children,” published in the journal Fetal and Pediatric Pathology, also pointed out that more severe leakage of blood into the urine in childhood may be a sign of Alport disease.

In South Korea, analyses of urine samples are part of routine check-ups in school-aged children. This has led to an increase in identification of people with traces of blood in the urine, as well as patients diagnosed with thin basement membrane disease.

Researchers at the Kyungpook National University School of Medicine in Korea analyzed long-term outcomes of a group of children. Among 58 patients who had been diagnosed with thin basement membrane disease (TBMN) with the help of a kidney biopsy, none had a family history of Alport disease.

The most common findings in the group were blood leakage into the urine, of varying severity. The patients were followed for an average of 8.9 years. During this time, three patients developed more severe signs of kidney disease.

In addition to blood leakage, they also started leaking proteins. After a second kidney biopsy, they were diagnosed with Alport disease. A high-resolution microscopic analysis of the kidney tissue showed typical Alport changes.

Comparing the characteristics between the three Alport patients and those with thin basement membrane disease, the research team found that all three had shown signs of mixed hematuria at early disease stages. Mixed hematuria is a state when a combination of microscopic and more severe blood leakage occurs.

In contrast, patients with thin basement membrane disease had microscopic leakage that did not worsen over time. Although none of the Alport children had eye problems, one had impaired hearing.

Also, the three Alport patients had been diagnosed with thin basement membrane disease at earlier ages than the rest of the group; 2.1 years compared to 8.1 years. They also had thinner basement membranes. Researchers could not conclude, however, if the difference in thickness was merely mirroring the age difference.

“We conclude that the possibility of AS should be considered in all children diagnosed with thin basement membranes during childhood and genetic or IF study for type IV collagen should be done in all patients with thin basement membranes. Continued monitoring of all patients with TBMN is still necessary to detect those that may have [Alport disease],” the authors wrote.