Urine Testing Enables Easier Diagnosis of Mitochondrial Disorders

These diseases are caused by pathogenic variants in the mitochondrial genome (mtDNA) or the nuclear genome (nDNA), which impair mitochondrial function and/or structure. Although there is no cure for PMD, timely treatment can prevent life-threatening complications, making early diagnosis essential. Unfortunately, these disorders are challenging to diagnose because their symptoms overlap with those of other conditions, such as neuromuscular disorders like myasthenia gravis and muscular dystrophy. At present, the diagnosis can only be confirmed through molecular genetic testing, which is resource-intensive. New research, however, may simplify the diagnosis of these severe diseases that disrupt the body’s energy production.

In a new study, researchers at the University of Alberta (Edmonton, Canada) examined 297 individuals with suspected primary mitochondrial disorders to better understand their causes and improve both diagnosis and treatment. Published in Orphanet Journal of Rare Diseases, this study was the first to evaluate mitochondrial DNA testing in urine, an approach that is less expensive and does not require a muscle biopsy. This method offers the potential for quicker and more widespread diagnosis of primary mitochondrial disorders. The study also uncovered differences in how these disorders affect adults and children. Adults are more likely to have a disorder caused by errors in mitochondrial DNA in their cells, while children are more likely to have conditions due to nuclear DNA errors. Additionally, muscle-related issues were found to be more prevalent in adults, whereas brain and developmental problems were more common in children. Recognizing these differences can help doctors choose the appropriate DNA tests and provide tailored treatment and management recommendations for both children and adults.

“With our study, we were hoping to show the differences between primary mitochondrial disorders and non-PMDs and then give specific recommendations for appropriate genetic tests depending on the age of patients,” said principal investigator Saadet Andrews. “We are hoping that it helps guide physicians and clinicians in their thinking about who should receive which genetic investigations, and that it can reduce the time it takes for patients to get a diagnosis.”