Road to recovery: Managing an epidemic.

Without widespread immunization, the road to recovery from the current COVID-19 lockdowns will optimally follow a path that finds the difficult balance between the social and economic benefits of liberty and the toll from the disease. We provide an approach that combines epidemiology and economic models, taking as given that the maximum capacity of the healthcare system imposes a constraint that must not be exceeded. Treating the transmission rate as a decreasing function of the severity of the lockdown, we first determine the minimal lockdown that satisfies this constraint using an epidemiology model with a homogeneous population to predict future demand for healthcare. Allowing for a heterogeneous population, we then derive the optimal lockdown policy under the assumption of homogeneous mixing and show that it is characterized by a bang-bang solution. Possibilities such as the capacity of the healthcare system increasing or a vaccine arriving at some point in the future do not substantively impact the dynamically optimal policy until such an event actually occurs.

L-leucine improves anemia and growth in patients with transfusion-dependent Diamond-Blackfan anemia: Results from a multicenter pilot phase I/II study from the Diamond-Blackfan Anemia Registry.

BACKGROUND: Diamond-Blackfan anemia (DBA) is an inherited bone marrow failure syndrome characterized by anemia, short stature, congenital anomalies, and cancer predisposition. Most cases are due to mutations in genes encoding ribosomal proteins (RP) leading to RP haploinsufficiency. Effective treatments for the anemia of DBA include chronic red cell transfusions, long-term corticosteroid therapy, or hematopoietic stem cell transplantation. In a small patient series and in animal models, there have been hematologic responses to L-leucine with amelioration of anemia. The study objectives of this clinical trial were to determine feasibility, safety, and efficacy of L-leucine in transfusion-dependent patients with DBA. PROCEDURE: Patients ≥2 years of age received L-leucine 700 mg/m2 orally three times daily for nine months to determine a hematologic response and any improvement in growth (NCT01362595). RESULTS: This multicenter, phase I/II study enrolled 55 subjects; 43 were evaluable. There were 21 males; the median age at enrollment was 10.4 years (range, 2.5-46.1 years). No significant adverse events were attributable to L-leucine. Two subjects had a complete erythroid response and five had a partial response. Nine of 25, and 11 of 25, subjects experienced a positive weight and height percentile change, respectively, at the end of therapy. CONCLUSIONS: L-leucine is safe, resulted in an erythroid response in 16% of subjects with DBA, and led to an increase in weight and linear growth velocity in 36% and 44% of evaluable subjects, respectively. Further studies will be critical to understand the role of L-leucine in the management of patients with DBA.

Diminutive somatic deletions in the 5q region lead to a phenotype atypical of classical 5q- syndrome.

Classical 5q- syndrome is an acquired macrocytic anemia of the elderly. Similar to Diamond Blackfan anemia (DBA), an inherited red cell aplasia, the bone marrow is characterized by a paucity of erythroid precursors. RPS14 deletions in combination with other deletions in the region have been implicated as causative of the 5q- syndrome phenotype. We asked whether smaller, less easily detectable deletions could account for a syndrome with a modified phenotype. We employed single-nucleotide polymorphism array genotyping to identify small deletions in patients diagnosed with DBA and other anemias lacking molecular diagnoses. Diminutive mosaic deletions involving RPS14 were identified in a 5-year-old patient with nonclassical DBA and in a 17-year-old patient with myelodysplastic syndrome. Patients with nonclassical DBA and other hypoproliferative anemias may have somatically acquired 5q deletions with RPS14 haploinsufficiency not identified by fluorescence in situ hybridization or cytogenetic testing, thus refining the spectrum of disorders with 5q- deletions.

How I treat Diamond-Blackfan anemia.

Diamond-Blackfan anemia (DBA) is characterized by red cell failure, the presence of congenital anomalies, and cancer predisposition. In addition to being an inherited bone marrow failure syndrome, DBA is also categorized as a ribosomopathy as, in more than 50% of cases, the syndrome appears to result from haploinsufficiency of either a small or large subunit-associated ribosomal protein. Nonetheless, the exact mechanism by which haploinsufficiency results in erythroid failure, as well as the other clinical manifestations, remains uncertain. New knowledge regarding genetic and molecular mechanisms combined with robust clinical data from several international patient registries has provided important insights into the diagnosis of DBA and may, in the future, provide new treatments as well. Diagnostic criteria have been expanded to include patients with little or no clinical findings. Patient management is therefore centered on accurate diagnosis, appropriate use of transfusions and iron chelation, corticosteroids, hematopoietic stem cell transplantation, and a coordinated multidisciplinary approach to these complex patients.