Interstitial Lung Disease Due to Systemic Disease (Telomere Biology Disorder)

The CT-IPF ANTHEM study is designed to prospectively compare PCDCT to HRCT scan in the identification of specific ILD diagnosis discussed during the multidisciplinary discussion to increase diagnostic confidence and reduce unclassifiable ILD cases.

The goal of this clinical trial is to learn if a combination therapy of deoxycytidine (dC) plus deoxythymidine (dT) is safe in patients with telomere biology disorders. The main questions it aims to answer are: * Is the therapy safe with tolerable side effects in patients with telomere biology disorders? * Are problems with the bone marrow or blood or lungs changed after 6 months of dC+dT treatment in patients with telomere biology disorders? Participants will: * Take study drug by mouth three times daily for 24 weeks * Make approximately 2 visits to Boston Children's Hospital during the 24 weeks: once at the beginning of treatment and once at the end of treatment. * Go to a lab for a blood draw an additional 6 times during treatment. * Have 9 phone calls with a research nurse, including one 4 weeks after treatment ends. * Keep a diary to track doses of study drug that were taken or missed.