Mutations in various domains of RTEL1, including the helicase domain, have been associated with telomere biology disorders such as dyskeratosis congenita, Hoyeraal–Hreidarsson syndrome, pulmonary fibrosis, bone marrow failure syndrome, myeloid neoplasms, and increased susceptibility to brain tumors [41, 46, 47]. This evidence concerns the gene RTEL1 and dyskeratosis congenita.