The main causes of HSC exhaustion are directly related to mutations in telomerase components (i.e. dyskeratosis congenita (due to mutation of the RNA component of telomerase (TERC) or a hereditable heterozygous mutation in TERT responsible for autosomal dominant aplastic anemia) [46] and may lead to accelerated telomere erosion. The gene discussed is TERT; the disease is dyskeratosis congenita.