Hemoglobin Yamagata: hemoglobin variant detected by HbA1c test

Area of Science:

• Hematology
• Clinical Chemistry
• Genetics

Background:

• Hemoglobin (Hb) Yamagata is a rare beta-globin gene variant, previously reported in only two individuals.
• It results from a specific amino acid substitution (Lysine to Asparagine) at codon 133.
• This study documents the third reported case of Hb Yamagata.

Observation:

• A 70-year-old Korean man with diabetes mellitus was diagnosed with Hb Yamagata.
• Initial HbA1c measurement using Variant II Turbo showed an abnormally high result (47.9%).
• Other methods yielded varying HbA1c levels, indicating interference.

Findings:

• Hb Yamagata significantly interferes with the accurate measurement of HbA1c, particularly with certain analytical platforms.
• The variant led to discrepant HbA1c readings across different testing devices.
• Accurate HbA1c determination requires careful consideration of potential interference from Hb variants.

Implications:

• Diabetic patients with suspected Hb variants require careful HbA1c monitoring.
• Immunoassay or affinity chromatography are suggested as alternative methods for reliable HbA1c measurement in patients with Hb Yamagata.
• Discrepancies in HbA1c results across different methods may indicate the presence of an abnormal hemoglobin variant.