| Domain | Finding (with numbers) | Study/source | Publication date | URL/DOI | Evidence type | Notes |
|---|---|---|---|---|---|---|
| Common causal variant | MT-TL1 m.3243A>G accounts for ~80% of MELAS cases | Na & Lee, *Biomolecules*; Xu et al., *Orphanet J Rare Dis* (pqac-00000002, pqac-00000003) | 2024-11; 2024-12 | https://doi.org/10.3390/biom14121524; https://doi.org/10.1186/s13023-024-03511-4 | Review; retrospective cohort | Xu reports OMIM #540000; Xu cohort n=29 |
| Neuroimaging lesion distribution | Posterior brain predominance: occipital 37/59 (63%), parietal 32/59 (54%), temporal 30/59 (51%); lesion polymorphism 37/59 (63%); cerebral atrophy 38/59 (64%); cerebellar atrophy 40/59 (68%); basal ganglia calcification 6/9 (67%); MRS lactate peak 9/10 (90%); arterial dilation 4/6 (67%) | Zheng et al., *Front Neurosci* (pqac-00000000) | 2023-01 | https://doi.org/10.3389/fnins.2022.1028762 | Retrospective imaging cohort | 59 imaging studies in 24 genetically confirmed m.3243A>G patients |
| Prognostic markers | Mean follow-up 7.3 ± 4.7 years; deaths 8/39; severe lactate elevation predicted mortality: OR 7.279 (95% CI 1.102–48.086, p=0.039); anemia associated with poor prognosis: OR 0.137 (95% CI 0.021–0.908, p=0.039); lactate vs mRS r=0.460 (p=0.003); hemoglobin vs mRS r=-0.375 (p=0.015) | Gao et al., *Front Neurol* (pqac-00000004) | 2024-12 | https://doi.org/10.3389/fneur.2024.1491283 | Retrospective cohort | Single-center MELAS cohort n=39; all initially presented with stroke-like episodes |
| Phenotype frequencies and survival | Seizures in MELAS 88.1% vs 16.7% in symptomatic non-MELAS; sensorineural hearing loss as first symptom 51.6% in symptomatic non-MELAS vs 24.4% in MELAS; mean serum heteroplasmy 39.3% (MELAS) vs 29.3% (symptomatic non-MELAS) vs 21.8% (asymptomatic); 50% mortality at 25 years in MELAS vs 10% comparison group; late-onset MELAS: diabetes 69.2%, nephropathy 53.8% | Cox et al., *Front Neurol* (pqac-00000001, pqac-00000009) | 2023-12 | https://doi.org/10.3389/fneur.2023.1298569 | Retrospective cohort | Overall n=81: 42 MELAS, 30 symptomatic non-MELAS, 9 asymptomatic; 13 late-onset MELAS |
| Taurine trial outcomes | High-dose taurine 9 g/day or 12 g/day for 52 weeks; 100% responder rate 60% (95% CI 26.2–87.8); ≥50% responder rate 80% (95% CI 44.4–97.5); annual relapse rate reduced 2.22 to 0.72 (P=0.001); no severe adverse events | Ohsawa et al., *J Neurol Neurosurg Psychiatry* (pqac-00000015, pqac-00000016) | 2019-04 | https://doi.org/10.1136/jnnp-2018-317964 | Multicentre open-label phase III trial | n=10 with recurrent stroke-like episodes; trial registration UMIN000011908 |
| Population-based prevalence/incidence | Adult mtDNA-related mitochondrial disease prevalence 9.2/100,000 (95% CI 6.5–12.7) in 2022; adult m.3243A>G-related disease prevalence 4.2/100,000 (95% CI 2.5–6.7); annual incidence of adult mtDNA disease 0.6/100,000; annual incidence of adult m.3243A>G-related disease 0.3/100,000 | Martikainen & Majamaa, *BMJ Neurol Open* (pqac-00000009) | 2024-02 | https://doi.org/10.1136/bmjno-2023-000546 | Population-based observational study | Southwest Finland, 2009–2022; 42 new adult patients diagnosed; mean 3.2 new diagnoses/year |


*Table: This table compiles key quantitative findings on MELAS syndrome from recent and landmark studies, including genetics, imaging, prognosis, phenotype burden, treatment outcomes, and population epidemiology. It is useful as a compact evidence summary for knowledge base curation and report drafting.*