CLINICAL AND MOLECULAR CHARACTERISATION OF SLC31A1-RELATED NEURODEVELOPMENTAL DISORDER.

Copper is indispensable for various metabolic processes, notably mitochondrial respiration. In humans, copper homeostasis hinges on transporters such as copper transporter 1 (CTR1), encoded by the SLC31A1 gene. Recently, bi-allelic mutations in SLC31A1 have been associated with a new neurodevelopmental disorder. This study presents clinical, genetic, and biochemical findings from 13 new cases across 10 families worldwide. RNA sequencing evaluated gene expression, and Western blotting assessed CTR1 protein levels. Additionally, mitochondrial respiratory capacity was measured via high-resolution respirometry. Affected individuals exhibited a distinct clinical phenotype characterized by early-onset epileptic encephalopathy, severe neurodevelopmental delay and hypotonia, with high mortality. Neuroimaging revealed significant brain atrophy and white matter abnormalities. Genetic analysis identified bi-allelic SLC31A1 variants, predominantly p.His120Gln in six cases and p.(Arg102Cys/His) in three cases. Functional studies in patient fibroblasts demonstrated impaired mitochondrial respiration. This study significantly broadens the clinical spectrum of this recently described syndrome, presenting as a severe developmental encephalopathy with high mortality risk, and suggests mitochondrial dysfunction as a potential pathomechanism. These findings contribute to the mounting evidence linking CTR1 dysfunction to neurodegeneration, underscoring the urgency for further therapeutic investigations.