Hb Oita [alpha45(CE3)His-->Pro]: a new silent hemoglobin variant.

We describe a new alpha chain variant accidentally found in a 49-year-old female living in Usa City, Oita Prefecture, Japan. An abnormally low Hb A1c value of 2.5% (normal range: 4.8-6.3%) was found while she was treated with glucocorticoid for Fisher syndrome. The patient was also diagnosed as having an iron deficiency anemia, but otherwise showed a normal hemogram. An abnormal hemoglobin was not detectable by isoelectrofocusing and high performance liquid chromatographic methods, but appeared as a fast-moving alpha chain abnormality by urea-carboxymethyl cellulose column chromatography of the globin, from which the content of the abnormal hemoglobin was estimated at approximately 20%. The instability test of the hemolysate was normal. Structural studies demonstrated that the abnormal hemoglobin had an amino acid substitution of His-->Pro at alpha45. It is a new variant and was named Hb Oita or alpha45(CE3) His-->Pro. Additionally, sequence analysis showed a nucleotide change from A-->C at the second base in the 45th codon of the alpha2 gene, CAC(His)-->CCC (Pro). The beta/alpha ratio was 0.51 (normal range: 0.9-1.2). Her mother and a son did not have the abnormal hemoglobin variant; her father was deceased and no sample was available to verify the inheritance of the variant in this kindred.