Depletion of some iron-containing proteins such as DNA polymerases Polα, δ, and ε, Regulator of telomere length 1 (RTEL1), and the small subunit of Ribonucleotide reductase (RNR) results in abnormal TL.35–37 Moreover, patients with diseases caused by iron deficiency or iron overload also have short TL.38,39. The gene discussed is RTEL1; the disease is nutritional disorder.