Expansion of the phenotypic spectrum of KARS1-related disorders to include arthrogryposis multiplex congenita and summary of experiences with lysine supplementation.

There are currently multiple disorders of aminoacyl-tRNA synthetases described, including KARS1-related disorder resulting from dysfunctional lysyl-tRNA synthetases. In this report, we describe four novel KARS1 variants in three affected individuals, two of whom displayed arthrogryposis-like phenotypes, suggestive of phenotypic expansion. We also highlight subjective clinical improvement in one subject following lysine supplementation in conjunction with a protein-fortified diet, suggesting its potential as a novel treatment modality for KARS1-related disorders. This report offers additional insight into the etiology and management of KARS1-related disorders and expands our ability to provide guidance to affected individuals and their families.