Telomerase enzyme. Simplified illustration of the telomerase enzyme showing its main components: hTERT, hTERC, Dyskerin, NOP10, NHP2, GAR1, and TCAB1. Functional regions of the hTERC RNA (template, pseudoknot, CR4-CR5, Box H/ACA, and CR7) are indicated. Mutations in hTERT, hTERC, TCAB1, NOP10 or Dyskerin have been shown to be associated with a severe form of human bone-marrow deficiency known as dyskeratosis congenita.