[An abnormal hemoglobin which was found by chance at a health checkup]

A 68-year-old female visited our hospital because of low hemoglobin A1c content, which was found by chance at a health checkup. She did not have any symptom or sign except hypertension and low HbA1c. To determine the reason why HbA1c was so low in usual laboratory test, we carried out isoelectrofocusing (IEF) of the hemolysate, Hb instability test, and detection and isolation of the abnormal globin chain by urea CM-cellulose column chromatography. The abnormal beta-globin chain was digested with TPCK-trypsin, and the tryptic peptides were separated by HPLC on a reversed phase column. Finally the determination of amino acid composition and amino acid sequence of the abnormal peptide were performed. The Hb variant was identified as Hb Riyadh (beta 120Lys-->Asn). The detection and analysis of abnormal hemoglobin will be expected to increase in accordance with the increased opportunity of public health checkup.