Hemoglobin Sherwood Forest detected by high performance liquid chromatography for hemoglobin A1c.

Hb Sherwood Forest has been so far identified in only one patient in 1977. This study describes the second detection of this hemoglobin variant by routine high performance liquid chromatography (HPLC) in a diabetic patient and her healthy grand niece. In both, glycosylated hemoglobin (HbA1c) values were excessively elevated (52%), as determined by HPLC with a cation exchange column. The latex agglutination test showed values of HbA1c in the expected normal range. Citrate agar electrophoresis revealed a hemoglobin variant with a mobility similar to HbF. Amino acid analysis and DNA sequence analysis revealed an Arg-->Thr exchange at codon 104 of the beta-chain. This sequence has been described as Hb Sherwood Forest in 1977. The hemoglobin variant is clinically silent and might be confused with excessively high HbA1c in routine measurement of glycosylated hemoglobin.