Genetic study of a case with abnormal hemoglobin Ta-li combined with hereditary persistence of fetal hemoglobin / 中华检验医学杂志

ABSTRACT

ObjectiveTo investigate the genotype of a case with abnormal hemoglobin combined with hereditary persistence of fetal hemoglobin (HPFH).Methods Male patient,26 years old,were suspected abnormal hemoglobin combined with HPFH after receiving medical examination including hematology exmination,hemoglobin electrophoresis,erythrocyte osmotic fragility analysis in Guangzhou Kingmed Diagnostics in September 2010.Routine examination of anemia and hemoglobin electrophoresis at alkaine pH on agarose gels were applied to analyze the phenotype.Direct sequencing of the complete HBB gene was utilized to identify the hemoglobin variant.Multiplex ligation-dependent probe amplification (MLPA) assay was used to identify the presence of β-globin gene cluster deletion.Gap polymerase chain reaction (gap-PCR) was used to amplify the HBB gene fragment across the breakpoint,and the deletion breakpoint was characterized by direct sequencing the gap-PCR product and comparing the sequencing result with the reference sequence NC_000011.9.ResultsBy direct sequencing of the complete HBB gene,the patient in this study was found to carry a hemoglobin Ta-Li (HBBc.250G ＞ T) mutation.By combining use of MLPA and gap-PCR with gene sequencing,we found that it had a gross deletion in the β-globin gene cluster,the deletion region was NC_000011.9g.5222878_5250288del.Therefore,the genotype of this subject was SEA-HPFH combined with abnormal hemoglobin Ta-li.ConclusionCombining application of MLPA and gap-PCR with gene sequencing can help to make sure the genotype.