Triallelic and epigenetic-like inheritance in human disorders of telomerase

Laura C. Collopy, Amanda J. Walne, Shirleny Cardoso, Josu De La Fuente, Mahfuzah Mohamed, Helga Toriello, Hannah Tamary, Adam J.Y.V. Ling, Timothy Lloyd, Rebecca Kassam, Hemanth Tummala, Thomas J. Vulliamy*, Inderjeet Dokal

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


Dyskeratosis congenita (DC) and related diseases are a heterogeneous group of disorders characterized by impaired telomere maintenance, known collectively as the telomeropathies. Disease-causing variants have been identified in 10 telomere-related genes including the reverse transcriptase (TERT) and the RNA component (TERC) of the telomerase complex. Variants in TERC and TERT can impede telomere elongation causing stem cells to enter premature replicative senescence and/or apoptosis as telomeres become critically short. This explains the major impact of the disease on highly proliferative tissues such as the bone marrow and skin. However, telomerase variants are not always fully penetrant and in some families disease-causing variants are seen in asymptomatic family members. As a result, determining the pathogenic status of newly identified variants in TERC or TERT can be quite challenging. Over a 3-year period, we have identified 26 telomerase variants (16 of which are novel) in 23 families. Additional investigations (including family segregation and functional studies) enabled these to be categorized into 3 groups: (1) disease-causing (n 5 15), (2) uncertain status (n 5 6), and (3) bystanders (n 5 5). Remarkably, this process has also enabled us to identify families with novel mechanisms of inheriting human telomeropathies. These include triallelic mutations, involving 2 different telomerase genes, and an epigenetic-like inheritance of short telomeres in the absence of a telomerase mutation. This study therefore highlights that telomerase variants have highly variable functional and clinical manifestations and require thorough investigation to assess their pathogenic contribution. (Blood.

Original languageEnglish
Pages (from-to)176-184
Number of pages9
Issue number2
StatePublished - 9 Jul 2015
Externally publishedYes


FundersFunder number
Medical Research Council
Medical Research CouncilMR/K000292/1


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