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INTRODUCTION: Haemoglobin (Hb) G-Philadelphia mutation is a common alpha-globin chain variant [α68(E17)Asn > Lys]. Combined high performance liquid chromatography (HPLC) and isoelectric focusing (IEF) can be used in a presumptive diagnosis of Hb G-Philadelphia, but there are other α-chain variants with a similar phenotype that cannot be excluded. Our aim was to develop a novel StyI restriction enzyme assay to diagnose the common Hb G-Philadelphia mutation and to identify any other variants with a similar phenotype by DNA sequencing. METHODS: Thirty-one cases given a presumptive diagnosis as Hb G-Philadelphia by HPLC and IEF were subjected to DNA analysis by restriction enzyme digestion using StyI. Negative cases were then subjected to DNA sequencing. RESULTS: Twenty-two cases (78.6%) of 28 cases amplified were tested positive for Hb G-Philadelphia by StyI restriction digestion. Sequencing of the six negative cases revealed two cases of Hb G-Philadelphia with C→A mutation in codon 68 in α2 globin gene, plus one case each of Hb G-Norfolk Hb Stanleyville-II, Hb Matsue-Oki and Hb Mizushi. CONCLUSION: A novel StyI restriction enzyme can be used to confirm the commonest type of Hb G-Philadelphia. DNA sequencing identified four other α-chain variants with a similar HPLC and IEF phenotype.

Original publication




Journal article


Int J Lab Hematol

Publication Date





318 - 325


Base Sequence, Codon, Deoxyribonucleases, Type II Site-Specific, Genetic Variation, Hemoglobins, Abnormal, Humans, Mutation, Phenotype, Sequence Analysis, DNA, alpha-Globins