Systemic inflammatory syndrome in children with FARSA deficiency

Variants in aminoacyl‐tRNA synthetases (ARSs) genes are associated to a broad spectrum of human inherited diseases. Patients with defective PheRS, encoded by FARSA and FARSB, display brain abnormalities, interstitial lung disease and facial dysmorphism. We investigated four children from two unrelated consanguineous families carrying two missense homozygous variants in FARSA with significantly reduced PheRS‐mediated aminoacylation activity. In addition to the core ARS‐phenotype, all patients showed an inflammatory profile associated with autoimmunity and interferon score, a clinical feature not ascribed to PheRS‐deficient patients to date. JAK inhibition improved lung disease in one patient. Our findings expand the genetic and clinical spectrum of FARSA‐related disease.