Effects Of Non-Deletional Hereditary Persistence Of Fetal Hemoglobin On Hb E And Hb E/β-Thalassemia

Objective:To explore the effects of non-deletional hereditary persistence of fetal hemoglobin（nd-HPFH）on clinical features in hemoglobin E（Hb E）and Hb E/β-thalassemia patients.Methods:Patients admitted to the First Affiliated Hospitol Of Guangxi Medical University from January 2016 to December 2017 for thalassemia diagnosis were involved into the study.Hematological profiles were performed.Hemoglobinanalysiswasquantitatedbyhighperformanceliquid chromatography（HPLC）.Gap polymerase chain reaction（Gap-PCR）was used for a genotyping for detection of deletionalα-thalassemia gene mutations.Genotypes of non-deletionalα-thalassemia andβ-thalassemia were done by fluorescence melting curve anylysis.Mutations of the gamma promoter were analyzed by DNA sequencing.Results:1.General data:Seventy six cases were identified as Hb E heterozygotes,in which the presence of nd-HPFH were noted in 36 cases.There were 34 Hb E/β-thalassemia,in which 18 cases were compounded with nd-HPFH.There were totaly 52 cases of male and 58 cases of female aged 1 to 61.2.Results of hematological parameters:（1）Hb E heterozygotes groups:Fourty cases of heterozygotes Hb E without nd-HPFH had hemoglobin（Hb）concentrations with a mean of 125.75 g/L,mean corpuscular volume（MCV）78.13 fL,mean corpuscular hemoglobin（MCH）25.23 pg and mean corpuscular hemoglobin concentration（MCHC）325.00 g/L.The Hb levels in 36 Hb E heterozygotes coinherited nd-HPFH were 119.55 g/L on average,MCV 75.74 fL,MCH 24.66 pg and MCHC 325.24 g/L on average.No significant differences were observed in Hb,MCV,MCH and MCHC levels between these two groups（P>0.05）.（2）Hb E/β-thalassemia groups:16 cases of Hb E/β-thalassemia without nd-HPFH had Hb concentrations with a mean of 67.87 g/L,MCV 69.53fL,MCH 21.02 pg and MCHC 298.62 g/L.18 cases of Hb E/β-thalassemia coinherited nd-HPFH had Hb levels with a mean of 76.38 g/L,MCV 75.50 fL,MCH 23.25 pg and MCHC 313.74 g/L on average,which was significant higher than that in Hb E/β-thalassemia wihout nd-HPFH（P<0.05）.3.Results of hemoglobin analysis:（1）Hb E heterozygotes groups:The Hb F values in 40 Hb E heterozygotes without nd-HPFH cases were 0.85%on average.The Hb F levels in 36 Hb E heterozygotes coinherited nd-HPFH were slightly increased with a mean of 1.30%,which was higher than that in Hb E heterozygotes without nd-HPFH（P<0.05）.（2）Hb E/β-thalassemia groups:16cases of Hb E/β-thalassemia without nd-HPFH resulted in elevated Hb F with an average of 14.42%.18 cases of Hb E/β-thalassemia coinherited nd-HPFH had increased Hb F expression（32.83%on average）,which was higher than that of the cases without nd-HPFH（P<0.05）.4.Identification of gene mutations:（1）Results ofβ-thalassemia gene mutations:76 cases were identified as heterozygotes Hb E,and 34 cases were identified as Hb E/β-thalassemia with genotypes ofββE/βCD17,ββE/βCD41-42,ββE/βCD71-72 andββE/βIVS-II-654.（2）Results ofγ-globin gene mutations:Among the 76 Hb E heterozygotes,36 cases were compounded with nd-HPFH,of which 8 Hb E carriers were identifed as heterozygotes for the ^Aγ-225^-222 deletion,21 as heterozygotes ^Gγ-158 C>T mutation,5 as homozygous ^Gγ-158 C>T mutation,and 2 as ^Aγ-225^-222 deletion compounded with heterozygotes ^Gγ158 C>T mutation.Among the 34 Hb E/β-thalassemia,18 cases were compounded with nd-HPFH,of which 17 cases were heterozygotes ^Gγ-158 C>T mutation,and 1 were homozygous ^Gγ-158 C>T mutation.（3）Results ofα-thalassemia gene mutations:（1）Hb E heterozygotes groups:4 cases were identified as deletionalα-thalassemia gene mutations(2 as-α^4.2/ααand 2 as--^SEA/αα),and 2 cases were identified as non-deletionalα-thalassemia gene mutations(α^CSα/αα)in Hb E heterozygotes without nd-HPFH.3 cases were identified as non-deletionalα-thalassemia gene mutations(α^CSα/αα)in Hb E heterozygotes coinherited nd-HPFH.（2）Hb E/β-thalassemia groups:3 cases were identified as deletionalα-thalassemia gene mutations(1 as-α^3.7/αα,1 as-α^4.2/ααand 1 as--^SEA/αα)in Hb E/β-thalassemia without nd-HPFH.No cases were identified asα-thalassemia gene mutations in Hb E/β-thalassemia coinherited nd-HPFH.Conclusion:1.nd-HPFH caused by ^Gγ-158 C>T mutation and ^Aγ-225^-222 deletion compounded with Hb E heterozygotes had slightly increased Hb F levels than that in Hb E heterozygotes without nd-HPFH,and there were no significant differences in Hb,MCV,MCH and MCHC levels between these two groups.2.nd-HPFH caused by ^Gγ-158 C>T mutation co-inherited with Hb E/β-thalassemia had elevated Hb F values,and had higher Hb,MCV,MCH and MCHC levels than that in Hb E/β-thalassemia without nd-HPFH.This suggests that nd-HPFH caused by ^Gγ-158 C>T mutation could result in an increased value of Hb F and attenuate clinical severity in Hb E/β-thalassemia patients.3.This study firstly characterized the ^Aγ-225^-222 deletion,and the ^Aγ-225^-222 deletion compounded with heterozygotes ^Gγ-158 C>T mutation in heterozygotes Hb E with slightly increased Hb F levels.