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.