YARS1 and hypothyroidism: In this study, we identified and characterized 10 newly diagnosed and two previously reported individuals carrying the homozygous missense variant NM_003680.3:c.1099C > T, p.(Arg367Trp) in YARS1 and summarized all previously published patients from the literature, carrying alternative, biallelic variants in YARS. We identified a specific multisystem disease affecting not only the central nervous system, but also the liver, the hematopoietic system (anemia), and the endocrine system (hypothyroidism).