Clinical Study Of 439 Fetuses With Hemoglobin H Disease

Objectives:To analyse the genotypes and hematological phenotypic characteristics of 439 fetuses with Hb H disease and their parents,investigate the related factors affecting pregnancy outcomes.Methods:We retrospectively analyzed 439 fetuses with Hb H disease that were diagnosed by prenatal gene test of thalassemia and their parents from June2013 to November 2017.Genetic and blood analysis were performed,general and abnormal condition of pregnant women and fetuses were recorded,and pregnancy outcomes were followed up.SPSS22.0 statistical software was used to analyze the data.Results:1.The constituent ratio of genotypes in 439 Hb H fetuses:--^SEA/-α^3.7（39.41%）,--^SEA/α^CSα（30.30%）,--^SEA/-α^4.2（13.90%）,--^SEA/α^WSα（10.93%）,--^SEA/α^QSα（3.19%）,α^CSα/α^CSα（1.14%）,--^THAI/α^CSα（0.46%）,--^THAI/-α^3.7（0.23%）,--^THAI/-α^4.2（0.23%）and--^SEA/-α^2.4（0.23%）.2.The results of cord blood hematological analysis of Hb H fetuses with different genotypes:There was no statistical difference（P>0.05）in RBC,Hb,MCV and MCH levels between--^SEA/-α³.7.7 group and--^SEA/-α⁴.2.2 group.--^SEA/α^CSαgroup had higher level of MCV,but lower levels of RBC and Hb than that of--^SEA/α^WSαgroup,with significant difference（P<0.01）.--^SEA/-α³.7.7 group and--^SEA/-α⁴.2.2 group had higher levels of Hb and RBC,but lower levels of MCV and MCH than that of--^SEA/α^CSαgroup,with significant difference（P<0.01）.Hb and MCH levels in the--^SEA/-α³.7.7 group and--^SEA/-α⁴.2.2 group were significantly lower（P<0.01）than that in the--^SEA/α^WSαgroup.MCV levels in the--^SEA/-α³.7.7 group was lower than that in the--^SEA/α^WSαgroup,with statistical difference（P<0.05）.3.In this study,the most common parental genotype combination wasαα/α⁺+αα/α⁰（72.89%）.These parents had a one-in-four chance of having a child with Hb H disease.Compare parental blood routine test results of fetuses with--/-α^3.7,--/-α^4.2,--/α^CSαand--/α^WSαgenotypes.There were statistical differences（P<0.05）in MCV and MCH levels between--/-α⁴.2.2 and--/α^CSαgroups on the mother side.No statistical difference（P>0.05）was observed when the Hb,MCV and MCH levels were compared between any other groups.Compare blood routine test results of parents with different types ofα-thalassemia.The Hb,MCV and MCH levels ofα-thalassemia silent carrier groups,α-thalassemia trait groups and Hb H disease groups were decreased gradually and the differences between these three groups were statistically significant（P<0.01）.4.Statistically differences（P<0.05）were found between induced labor group and delivery group in parental genotype combinations and fetal specimen types.Significant differences（P<0.01）were found between induced labor group and delivery group in delivery times and fetal genotypes.Fetuses whose mother has reproduction history had a higher risk of being induced labor than those whose mother has no reproduction history（OR=2.950,P<0.01）.Fetuses whose parental genotype combination wasαα/α⁰+α⁺/α⁰ had a lower risk of being induced labor than those whose parental genotype combination wasαα/α⁺+αα/α⁰（OR=0.230,P<0.01）.Fetuses whose specimen types used for confirmation were villi had a higher risk of being induced labor than those whose specimen types used for confirmation were amniotic fluid（OR=0.469,P<0.01）and umbilical cord blood（OR=0.225,P<0.05）.Fetuses with genotype--/α^CSαhad a higher risk of being induced labor than those with genotype--/-α^3.7（OR=16.159,P<0.01）.Fetuses with genotype--^SEA/α^WSαhad a lower risk of being induced labor than those with genotype--^SEA/-α^3.7（OR=0.206,P<0.01）.Conclusions:1.--^SEA/-α³.7.7 is the most common genotype of Hb H fetuses in this study,followed by--^SEA/α^CSα,--^SEA/-α⁴.2.2 and--^SEA/α^WSα.The hematological phenotypes severity of fetuses is shown as--^SEA/α^CSα>--^SEA/-α^3.7=--^SEA/-α^4.2>--^SEA/α^WSα.2.The most common genotype combination for parents of Hb H fetuses isαα/α⁺+αα/α⁰.The hematological phenotypes of parents were related to their ownα-thalassemia types,but not to the genotypes of their fetuses.3.Fetuses with--/α^WSα,--/-α³.7.7 and--/α^CSαgenotypes are at increased risk of being induced labor.Fetal genotypes,parental genotype combinations,delivery times and the gestational week at which the fetus was diagnosed can all affect the risk of fetus being induced labor and should be given adequate attention in genetic counseling.