A six-year-old boy with a history of anemia was referred to the Boston Children’s Bone Narrow Clinic for evaluation. Bone marrow was reviewed due to a low lymphocyte count, which suggested a diagnosis of an unusual genetic anemia turned into congenital dyserythropoietic anemia. Through subsequent genetic testing, two variants in a gene not previously associated with dyserythropoietic anemias were identified. Importantly, this gene had been associated with an immunodeficiency, which could account for the patient’s mild leucopenia, and led to further investigation of the patient’s immune system. In retrospect, the child had multiple ear infections and a persistent cough for the last year, suggesting a clinical immunodeficiency. A review of other patients in the study database identified another patient with mutations in the same gene with an overlapping phenotype. This discovery led to the conclusion that mutations in this gene should be considered in the diagnosis of rare anemias. In the case of these two patients, long-term intravenous immunoglobulin therapy will be started to prevent future infections.