Spermidine supplementation in rare translation-associated disorders.

The polyamine spermidine is essential for protein translation in eukaryotes, both as a substrate for the hypusination of the translation initiation factor eIF5A as well as general translational fidelity. Dwindling spermidine levels during aging have been implicated in reduced immune cell function through insufficient eIF5A hypusination, which can be restored by external supplementation. Recent findings characterize a group of novel Mendelian disorders linked to EIF5A missense and nonsense variants that cause protein translation defects. In model organisms that recapitulate these mutations, spermidine supplementation was able to alleviate at least some of the concomitant protein translation defects. Here, we discuss the role of spermidine in protein translation and possible therapeutic avenues for translation-associated disorders.