AARS1 and trichothiodystrophy: Whole-exome/genome sequencing of unsolved non-photosensitive trichothiodystrophy (NPS-TTD) cases revealed compound heterozygous AARS1 mutations in two patients (TTD236AM and TTD1GL), which featured significantly reduced cellular levels of the AARS1 protein in patient fibroblasts, causing protein instability and impaired enzymatic activity [23].