EPO and anemia (phenotype): All five affected individuals presented symptoms consistent with a TBD, including macrocytic anemia with bone marrow hypocellularity (n = 5/5) managed with erythropoietin and blood transfusions, fibrotic interstitial lung disease or restrictive spirometric pattern (n = 4/5), graying of hair before age 20 (n = 4/5), and low-trauma fractures (n = 2/5).