Hb Stara Zagora: a new hyper-unstable hemoglobin causing severe hemolytic anemia

Area of Science:

• Hematology
• Genetics
• Molecular Biology

Background:

• Hemoglobinopathies represent a significant global health burden.
• Genetic mutations in the beta-globin gene can lead to unstable hemoglobin variants and hemolytic anemia.
• Early diagnosis and characterization of novel hemoglobin variants are crucial for patient management.

Observation:

• A 2-year-old Bulgarian boy presented with severe hemolytic anemia requiring regular blood transfusions since infancy.
• Hemoglobin analysis revealed inclusion bodies, but no gross abnormalities, in peripheral blood.
• Genetic sequencing identified a novel 6 bp deletion in the beta-globin gene.

Findings:

• A new hyper-unstable beta chain variant, Hb Stara Zagora (codons 137-139, -6 bp), was identified.
• The deletion results in the elimination of three amino acids (Val-Ala-Asn) and the introduction of a new residue (Asp).
• This mutation creates a new restriction site for HphI, facilitating its detection.

Implications:

• This discovery expands the spectrum of known unstable hemoglobin variants.
• Understanding this mutation's impact on hemoglobin stability and red blood cell function is vital.
• Further research may elucidate the specific mechanisms underlying hyper instability and guide therapeutic strategies for related anemias.