Puja Thapa

Pontocerebellar Hypoplasia Type 6 (PCH6) is a type of mitochondrial disease with early-onset encephalopathy caused by recessive mutations in mitochondrial arginyl-tRNAsynthetase gene (RARS2). Characteristic clinical features comprise of neonatal lactic acidosis, severe encephalopathy, intractable seizures, feeding problems and profound developmental delays. Most patients show typical neuroradiologic abnormalities including cerebellar hypoplasia and progressive pontocerebellar atrophy. There is currently no cure and therapeutic interventions are aimed at symptomatic relief. Significant advances have been made in our understanding of the pathophysiology of mitochondrial disease, however, due to large genetic heterogeneity and numerous missense variations of uncertain significance, the pathogenesis of PCH6 remains unclear. In this project, we aim to elucidate the mechanisms by which variants in RARS2 lead to the development of PCH6 and assess the efficacy of restoring RARS2 gene via gene therapy in preclinical models. Towards these aims, we will first characterise PCH6 disease phenotype in RARS2 variant-iPSC derived brain organoids. We will then design, and generate clinical cassettes containing RARS2 to transduce brain organoids. Following transduction, organoids will be evaluated for the safety and efficacy of gene therapy treatment.