Sarcouncil Journal of Medicine and Surgery

Abstract: We read with interest the article by Miyahara et al. who reported an autopsy study of six brains from patients carrying the mtDNA variant m.3243A>G in MT-TL1 [Miyahara, H. et al., 2023]. Five of the six patients were classified as mitochondrial encephalopathy, lactic acidosis, and stroke-like episode (MELAS) syndrome [Miyahara, H. et al., 2023]. The sixth patient had a non-syndromic mitochondrial disorder (MID) [Miyahara, H. et al., 2023]. The researchers found swelling of smooth muscle cells in leptomeningeal vessels, with immunoreactivity against mitochondria antibodies, and decreased nuclear/cytoplasmic ratio of choroidal epithelial cells in all mutant cases [Miyahara, H. et al., 2023]. Common neuropathological findings such as cortical laminar necrosis and basal ganglia calcification were not observed in all mutant cases [Miyahara, H. et al., 2023]. Despite heterogeneous cortical lesions, high levels of heteroplasmy have been observed throughout the brain [Miyahara, H. et al., 2023]. It was concluded that an absence of a medial temporal lesion, mitochondrial vasculopathy in vessels at the leptomeninges, and increased cytoplasmic size of epithelial cells in the choroid plexus could be helpful neuropathological features in the diagnosis of MID [Miyahara, H. et al., 2023]. The study is excellent but raises concerns that should be discussed.