Myeloid bodies may aid in Fabry diagnosis, treatment monitoring
Fatty deposits in urine seen as potential biomarker
Fatty deposits called myeloid bodies in urine may help diagnose Fabry disease and monitor how people with Fabry are responding to treatment, a study showed.
The study, “Urinary Myeloid Bodies as a Biomarker for Early Diagnosis and Monitoring of Enzyme Replacement Therapy in Fabry Disease,” was published in Kidney Diseases.
Fabry disease is caused by mutations in the gene that provides instructions to make the alpha-galactosidase A (alpha-Gal A) enzyme. This enzyme is normally needed to break down certain fatty molecules. In Fabry disease, lack of functional alpha-Gal A leads these fatty molecules to build up to toxic levels in cells, causing damage to organs.
Damage to the kidneys is a common manifestation of Fabry disease. The kidneys are normally responsible for filtering the blood and excreting waste into urine.
Myeloid bodies are abnormal clumps of fat-like molecules that build up inside cells in people with Fabry disease. Some of these clumps can be found in urine. These deposits, known as urinary myeloid bodies, were first described in the 1970s, but their exact role and importance in Fabry disease have not been well understood.
Detecting fatty deposits
To gain more insight, scientists in China tested for myeloid bodies in the urine of 25 people with Fabry disease. The researchers were able to detect these fatty deposits in urine from all but four of the patients. By contrast, in a separate group of people with other types of kidney disease, none had myeloid bodies detectable in their urine. These data indicate that although not everyone with Fabry disease has myeloid bodies in their urine, the presence of these fatty molecules may be a sign of Fabry.
Myeloid bodies were detectable in all the Fabry patients who had notable kidney dysfunction, and among patients who didn’t have myeloid bodies, none had notable kidney disease. There also were several patients who had myeloid bodies but no signs of kidney disease. These data suggest that myeloid bodies may be detectable in urine earlier than classic signs of kidney disease like protein in urine, the researchers said
Collectively, the data suggest “that urinary myeloid bodies may serve as noninvasive biomarkers for the early diagnosis of Fabry disease,” the scientists wrote.
A mainstay form of treatment for Fabry disease is enzyme replacement therapy (ERT), which works to deliver a working version of the alpha-Gal A enzyme to the body. During the study, seven participants had urinary myeloid bodies measured before and after a year of ERT treatment. Results showed that myelin body levels tended to decrease following ERT.
“After 1 year of ERT, both the number and area ratio of urinary myeloid bodies decreased, highlighting their potential as biomarkers for monitoring ERT effectiveness,” the researchers wrote.
The study was limited by the small number of patients involved, the researchers said.
“Future large-scale clinical studies are necessary to further explore the relationship between urinary myeloid body excretion and Fabry [kidney disease],” they wrote.
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