ZCCHC8 and dyskeratosis congenita: Through extensive genetic studies on a large cohort of clinically diagnosed DC and DCL cases, we identified several novel pathogenic variants within known genetic loci and discovered a new X-linked gene, POLA1. Functional curation of novel variants identified in POLA1, POT1 and ZCCHC8 genes expand the genetic and molecular basis associated with these conditions.