RTEL1 and Hoyeraal-Hreidarsson syndrome: The mutation in the RTEL1 gene has been linked to a variety of human diseases, including dyskeratosis congenita (DC), Hoyeraal-Hreidarsson syndrome, glioma (HHS), glioblastoma, pulmonary fibrosis, bone marrow failure, breast cancer, and other malignancies [4].