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. This evidence concerns the gene NR2E3 and Tangier disease.