TYMS and dyskeratosis congenita: What was also remarkable was that despite the clinical heterogeneity of the genetically uncharacterized DC probands included in our exome series, the TYMS families had a consistent phenotype, characterized by an early onset of mucocutaneous features (abnormal skin pigmentation and nail dystrophy) that are the predominant clinical features of classic DC (Figures 1B–1E; Table 1).