Identification of Hb C [beta 6(A3)Glu-->Lys] in a Thai male.
The propositus was a 29-year-old Thai male, whose electrophoretic pattern showed Hb A (58%) plus an abnormal hemoglobin (42%) with mobility identical to Hb A2 and Hb E. Protein sequencer analysis and tryptic peptide mapping of the beta chain indicated that the abnormal hemoglobin was Hb C [beta 6(A3)Glu-->Lys], rather than Hb E which is more commonly found in South East Asia. This conclusion was confirmed by direct sequence analysis of the propositus' DNA, which showed AAG as well as GAG at codon 6 of the beta gene, in agreement with heterozygosity for Hb C and Hb A. Furthermore, the beta gene framework (Ava II-, Bam HI+) of the propositus suggested that the beta C gene may have arisen from an independent mutation. Since Hb C and Hb E have the same mutation (Glu-->Lys) in the beta chain, although at different positions, and behave similarly in electrophoresis, cases of Hb C and Hb E may sometimes have been mistakenly identified for each other, based on whichever variant is most prevalent in the particular population.
Siriboon
W
W
Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand.
Srisomsap
C
C
Winichagoon
P
P
Fucharoen
S
S
Svasti
J
J
D000328:Adult; D000595:Amino Acid Sequence; D001483:Base Sequence; D004247:DNA / Q000032:analysis; D014644:Genetic Variation; D006403:Hematologic Tests; D006444:Hemoglobin C / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D013785:Thailand
D004247:DNA; D006444:Hemoglobin C