Mammalian chromosomes terminate in stretches of repetitive telomeric DNA that 
act as buffers to avoid loss of essential genetic information during 
end-replication. A multiprotein complex known as shelterin prevents recognition 
of telomeric sequences as sites of DNA damage. Telomere erosion contributes to 
human diseases ranging from BM failure to premature aging syndromes and cancer. 
The role of shelterin telomere protection is less understood. Mutations in genes 
encoding the shelterin proteins TRF1-interacting nuclear factor 2 (TIN2) and 
adrenocortical dysplasia homolog (ACD) were identified in dyskeratosis 
congenita, a syndrome characterized by somatic stem cell dysfunction in multiple 
organs leading to BM failure and other pleiotropic manifestations. Here, we 
introduce the biochemical features and in vivo effects of individual shelterin 
proteins, discuss shelterin functions in hematopoiesis, and review emerging 
knowledge implicating the shelterin complex in hematological disorders.