Purpose: In the past, detection of metabolic abnormalities in plasma amino acid (PAA) and
urine organic acid (UOA) has been widely used to diagnose clinical mitochondrial diseases,
such as mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes
(MELAS). In this study, the diagnostic values of PAA and UOA were reviewed, and their
effectiveness in the diagnosis of MELAS was examined retrospectively.
Methods: Blood and urine samples at the time of diagnosis were collected from all clinically
diagnosed MELAS patients (n=31), and PAA and UOA tests were performed. All samples
were collected in a fasting state to minimize artifacts in the results. The difference in the
ratio of abnormal metabolites of PAA and UOA at initial diagnosis was statistically compared
between the MELAS with genetic confirmation (n=19, m.3243A>G mutation) and MELAS
without genetic confirmation (n=12) groups. The MELAS without genetic confirmation group
was used as control.
Results: Comparison of PAA and UOA between the two groups revealed that no abnormal
metabolites showed characteristic differences between gene-confirmed MELAS patients with
and those without genetic confirmation.
Conclusions: Abnormal values of metabolites in PAA or UOA might be useful as a screening
test but are not sufficient to diagnose MELAS patients.