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Free-thiamine is a potential biomarker of thiamine transporter-2 deficiency: a treatable cause of Leigh syndrome

2015; Oxford University Press; Volume: 139; Issue: 1 Linguagem: Inglês

10.1093/brain/awv342

1460-2156

Juan Darío Ortigoza‐Escobar, Marta Molero‐Luis, Ángela Arias, Alfonso Oyarzábal, Niklas Darín, Mercedes Serrano, Àngels García‐Cazorla, Mireia Tondo, María Isabel Hernández, Judit García‐Villoria, Mercedes Casado, Laura Gort, Johannes A. Mayr, Pilar Rodríguez‐Pombo, Antònia Ribes, Rafael Artuch, Belén Pérez‐Dueñas,

Metabolism and Genetic Disorders

Thiamine transporter-2 deficiency is caused by mutations in the SLC19A3 gene. As opposed to other causes of Leigh syndrome, early administration of thiamine and biotin has a dramatic and immediate clinical effect. New biochemical markers are needed to aid in early diagnosis and timely therapeutic intervention. Thiamine derivatives were analysed by high performance liquid chromatography in 106 whole blood and 38 cerebrospinal fluid samples from paediatric controls, 16 cerebrospinal fluid samples from patients with Leigh syndrome, six of whom harboured mutations in the SLC19A3 gene, and 49 patients with other neurological disorders. Free-thiamine was remarkably reduced in the cerebrospinal fluid of five SLC19A3 patients before treatment. In contrast, free-thiamine was slightly decreased in 15.2% of patients with other neurological conditions, and above the reference range in one SLC19A3 patient on thiamine supplementation. We also observed a severe deficiency of free-thiamine and low levels of thiamine diphosphate in fibroblasts from SLC19A3 patients. Surprisingly, pyruvate dehydrogenase activity and mitochondrial substrate oxidation rates were within the control range. Thiamine derivatives normalized after the addition of thiamine to the culture medium. In conclusion, we found a profound deficiency of free-thiamine in the CSF and fibroblasts of patients with thiamine transporter-2 deficiency. Thiamine supplementation led to clinical improvement in patients early treated and restored thiamine values in fibroblasts and cerebrospinal fluid. Leigh syndrome caused by thiamine transporter-2 deficiency responds to early thiamine administration. Ortigoza-Escobar et al. reveal a severe reduction in free-thiamine in the CSF of children with transporter-2 deficiency, suggesting the suitability of free-thiamine as a biomarker. Early thiamine supplementation leads to clinical improvement in patients and restores thiamine levels.