Germline variants in the RTEL1 gene are etiologic in telomere biology disorders (TBD) [13,14,15,16], especially regenerative-defective disorders, such as dyskeratosis congenita (DC) and its more severe presentation, Høyeraal-Hreidarsson Syndrome (HHS), but also, in the heterozygous state, with lung fibrosis, bone marrow failure and other clinical manifestations [17,18,19,20,21,22]. This evidence concerns the gene RTEL1 and hypotrichosis 1.