Effects of Leucine Administration in Diamond-Blackfan Anemia Patients.

Diamond-Blackfan anemia (DBA) attracts much attention, since the symptoms of the disease are associated with mutations in ribosomal protein (RP) S19 in 25% of patients and in RPS17 and RPS24 in other DBA patients, indicating a possible relationship between ribosomal function, translation level and erythropoiesis. Indeed, translational efficiency has been found to be lowered in most DBA patients, and the amino acid leucine was tested in vitro as a potential modulator of protein synthesis with promising results. We therefore decided to evaluate the effects of leucine administration in several DBA patients. For leucine therapy, 4 patients with the lowest levels of translation (patients 1, 2, 4 and 6; see Table) and 2 others were selected from the Czech DBA registry. Due to iron overload, all patients were receiving iron chelation therapy at the start of the leucine therapy. A total dose of 2000 mg/m²/day of L-leucine was administered orally in three subdoses in the form of a capsule prepared by the hospital pharmacy. The doses were based on the leucine content in sports dietary protein supplements, and reduced according to each patient’s body surface area. Two and 4 hours after administration, serum leucine levels doubled, but did not exceed normal values. Changes in other amino acids serum levels were not observed. After 8 weeks of leucine supplementation, all patients reported a noticeable increase in appetite and weight gain. Over a period of 6 months of follow-up, a gradual improvement in reticulocyte counts, hemoglobin levels and a reduction of serum ferritin levels were observed in all patients (see Table). One patient became transfusion independent, and is currently still in remission (>5 months); in two other transfusion dependent patients, the inter-transfusion period doubled; in steroid-dependent patients, the steroid dose could be reduced. The patient with the RPS17 mutation significantly improved in weight and well-being, and the iron chelation therapy was stopped. Our results thus show for the first time that leucine administration can greatly improve the quality of life of DBA patients in at least two ways - it can reduce the need for iron chelation; and it can gradually enhance erythropoiesis, reducing the steroid dose or the frequency of transfusions.