Severe congenital neutropenia.

Area of Science:

• Hematology
• Genetics
• Immunology

Background:

• Severe congenital neutropenia (CN) involves low absolute neutrophil counts (ANC) (<0.5 x 10^9/L), leading to severe bacterial infections in infancy.
• Subtypes include Kostmann syndrome (autosomal recessive) and autosomal dominant forms, with genetic heterogeneity suggesting diverse pathophysiological mechanisms.
• Genetic instability, including mutations in ELA2 and G-CSF receptor genes, is a common feature across CN subtypes.

Purpose of the Study:

• To summarize the clinical features, genetic basis, and treatment responses of severe congenital neutropenia.
• To analyze the efficacy of recombinant human G-CSF (rHuG-CSF) in managing CN.
• To discuss adverse events associated with CN and G-CSF treatment, including malignant transformation.

Main Methods:

• Analysis of data from the Severe Chronic Neutropenia International Registry (SCNIR) (>600 patients).
• Review of genetic studies identifying mutations in ELA2 and other genes.
• Evaluation of patient response to rHuG-CSF and associated adverse events.

Main Results:

• Over 95% of CN patients respond to rHuG-CSF, maintaining ANC above 1.0 x 10^9/L.
• Common adverse events include mild splenomegaly, osteoporosis, and risk of myelodysplasia/leukemia.
• The relationship between G-CSF dose, neutrophil response, and acute myeloid leukemia (AML) risk is under investigation.

Conclusions:

• rHuG-CSF is highly effective in managing severe congenital neutropenia across various subtypes.
• Long-term monitoring for adverse events, including malignancy, is crucial for patients on G-CSF therapy.
• Hematopoietic stem cell transplantation (HSCT) remains the primary option for G-CSF-refractory cases.