The Pedigree Analysis And Prenatal Diagnosis Of Hong Kong??(HK??)thalassemia

Objective:This study aims to describe the phenotype of Hong Kong??(HK??)thalassemia,to trace the law of inheritance of this genotype,to perform the prenatal diagnosis on the unborn fetus and offer the couple a relatively exact as well as efficient prenatal counseling.Methods : Peripheral blood of all of the participants(except the unborn fetus)was collected into EDTA-containing tubes.Whole blood cell counts and hemoglobin electrophoresis tests were performed on participants(except the unborn fetus).8ml of amniotic fluid was collected from the proband's spouse.Genomic DNA was extracted from all individuals and fetal DNA was extracted from the amniotic fluid.Reverse dot blot was performed on all samples to detect the point mutation genotype of thalassemia.The single-tube multiplexpolymerase chain reaction(PCR)for four Chinese common deletional ? thalassemia types(-?3.7,-?4.2,--SEA and--THAI)was performed to determine the deletional genotype of ? thalassemia and the suspicious HK?? allele.PCR for the detection of ???anti4.2 allele was performed.The two round nested PCR was employed to determine the presence of the HK?? allele.Confirm the genotypes of all individuals and analyze the phenotypes.Results: The results indicated that five of the family members were positive for Hong Kong?? allele.One was diagnosed with the compound of HK??/-?3.7 and ?41-42M/?N.Two individuals with HK??/--SEA,?N/?N.Another two individuals were positive for HK??/-?4.2,?N/?N.The genotype of the unborn fetus was HK??/-?4.2,?N/?N.Conclusions: Hong Kong??,which is prone to be misdiagnosed,is a rare genotype of thalassemia.The combination of phenotype and the two-round nested PCR,which is a reliable laboratorial method,can help to avoid the possible underdiagnosis.