A gene therapy strategy for Deoxyhypusine Synthase (DHPS) syndrome

Deoxyhypusine synthase (DHPS) syndrome is a rare, autosomal recessive neurodevelopmental disorder caused by biallelic pathogenic variants in the DHPS gene, which encodes deoxyhypusine synthase. This enzyme is essential for the post-translational hypusination of eukaryotic translation initiation factor 5A (eIF5A), a modification crucial for cell viability, protein synthesis, and neuronal development. Patients with DHPS deficiency typically present with global developmental delays, intellectual disabilities, speech and motor impairments, seizures, and various dysmorphic features. Molecular studies show that DHPS mutations disrupt eIF5A hypusination, impairing translation elongation and cellular homeostasis. Animal and cellular models have confirmed the neurotoxic effects of impaired hypusination. Although no targeted therapy is available, advances in understanding the molecular basis of the disorder have enabled translational research, including modulation of polyamine metabolism. Here, we describe the development of a gene therapy strategy to deliver DHPS cDNA to mutant human brain cells in cortical organoids derived from patient stem cells, successfully restoring hypusination. This approach also improved survival in a mouse model of DHPS deficiency, highlighting the potential of rescuing DHPS expression as a treatment.