Chromosome Abnormalities And Single Nucleotide Polymorphism Of Related Genes In Patients With Conotruncal Defects

Congenital heart diseases(CHD) is one of the most commonly seen congenital defects in children,which can severely infleunce mortality and life quality of children. Conotruncal defect is a kind of complex congenital heart disease,it can cause hypoxemia and irreversible acidosis during neonatal period,thus,leads to early death. The pathogenesis of conotruncal defects has already been more highlighted. Reciprocity of multi-gene and environment are accepted as the cause of CHD.Reports showed that the major cardiac abnormality was conotruncal defects in patients with 22q11 microdeletion syndrome,while some patients with conotruncal defects had 22q11 microdeletion.Deletion of genes located on the segment of 22q11 microdeletion,such as TBX1 and HIRA,led to conotruncal defects in animal models. Thus,these genes were considered as candidate genes for conotruncal development. However,although conotruncal defect is the cardiac phenotype in 22q11 microdeletion syndrome,it is still controversial for the association of non-syndromic conotruncal defects and 22q11 microdeletion.On the other hand,the role of the genes in 22q11 in human being is still unclear.Our studies were to investigate the Chromosome Abnormalities including karyotypes and 22q11 microdeletion,and Single Nucleotide Polymorphism of TBX1 and HIRA Genes in Patients with Conotruncal Defects.The results will help to illustruate the pathogenesis of conotruncal defects.PartⅠThe retrospective analysis of the relationship of chromosome karyotypes and congenital heart diseasesObjective:To investigate the relationship between chromosome karyotypes and congenital heart diseases.Methods: Four thousand and forty-six children,who underwent chromosome karyotyping during 1990.1 to 2006.12,were analysed retrospectively.Chromosome karyotypes and heart abnormalities were evaluated.Results:1,Among 4046 cases,there were 660 cases(16.32%) with abnormal chromosome karyotypes,and 391 cases(9.66%) with congenital heart diseases.2,Among 660 cases with abnormal chromosome karyotypes,21-trisomy was detected in 458 cases(63.40%),and Truner syndrome was found in 105 cases (15.90%).3,Among 660 cases with abnormal chromosome karyotypes,185 cases had congenital heart diseases,of which 157 cases had 21-trisomy with 84.71%of septal defects.4 cases were Truner syndrome with 50%of coarctation of the aorta.4,Abnormal chromosome karyotypes were found in 185 out of 391(41.31%) cases of congenital heart diseases,while they were found in 475 out of 3655(13.0%) children with no heart diseases(x~2=304.7,P=0.000,OR=6.012,95%CI is 4.822-7.497).However,abnormal chromosome karyotypes were found in only 16 out of 105(15.24%) conotruncal defects,while they were found in 169 out of 286(59.1%) non-conotruncal defects(x~2=59.25,P=0.000,OR=8.035,95%CI is 4.489-14.380).Conclusions:1,21-trisomy is the most common type of abnormal autosomal chromosome karyotypes,in which septal defects are often seen.Truner syndrome is the most common type of abnormal sexual chromosome karyotypes,in which coarctation of the aorta may be often seen.2,Chromosome karyotype abnormality is not commonly seen in conotruncal defects,which suggests that routine chromosome karyotyping is not able to find conotruncal defects.PartⅡThe association of conotruncal defects and 22q11 microdeletionObjective:To investigate the association of 22q11 microdeletion with conotruncal defects.Methods:A cohort of 91 conotruncal defects patients was studied.Draw off 2ml blood from those children,and made chromosome image.Tuplel probe was used to do FISH test. Results:1,FISH was successfully performed in 83 cases,including PA/VSD(n=31),TOF (n=24),DORV(n=10),PS(n=7),TGA(n=5),PTA(n=4),CoA(n=1) and AS(n=1).2,22q11 microdeletion was observed in 3 cases with PA/VSD.The positive rate was 3.6%in total cases,and 9.7%in patients with PA/VSD.Conclusions:1,The incidence of 22q11 microdeletion is higher in PA/VSD than in other conotruncal defects.2,22q11 microdeletion probe can be used as ante partum examination,which may reduce natality of PA/VSD.PartⅢSingle nucleotide polymorphism of related genes in patients with conotruncal defectsObjective:To investigate the correlation of single nucleotide polymorphisms(SNPs) of TBX1 and HIRA genes with conotruncal defects.Methods:A cohort of 203 pediatric patients with conotruncal defects was recruited in the study,which included TOF(n=87),PA(n=49),TGA(n=32),DORV(n=29) and PTA(n=6) 150 patients with simple congenital heart diseases and 150 normal children were used as control.PCR and genotyping were performed for the detection of SNPs of TBX1 and HIRA genes.Results:1,Polymorphisms of TBX1 geneFrequencies of genotypes of G at position 2857 of TBX1 gene were 87.5%in TGA group and 75.3%in normal control group(X~2=4.821,P=0.028,OR=2.256, 95%CI is 1.079-4.718).The allele frequencies of the less common G variant were 64.1%in TGA group and 47.4%in normal control group(X~2=5.159,P=0.023, OR=1.926,95%CI is 1.093-3.393).2,Polymorphisms of HIRA gene(1) Frequencies of genotypes of G at position 25983 of HIRA gene were 6.2%in TGA group and 15.3%in simple congenital heart disease(X~2=4.310,P=0.038, OR=2.765,95%CI is 1.026-7.449),and 3.4%in DORV group and 15.3%in simple congenital heart disease(X~2=8.791,P=0.003,OR=5.706,95%CI is 1.597-20.368). But,the allele freguencies of the less common G variant were no difference between those groups.(2) Frequencies of genotypes of A at position 100308 of HIRA gene were 13.8% in TOF group and 3.3%in normal control group(X~2=7.779,P=0.005,OR=5.264, 95%CI is 1.463-18.937).16.7%in PTA(X~2=10.889,P=0.001,OR=6.622,95%CI is 1.874-23.391).The allele frequencies of the less common A variant were 8.6%in TOF group and 1.7%in normal control group(X~2=4.714,P=0.030,OR=4.846,95%CI is 1.020-23.084).16.7%in PTA(X~2=13.085,P=0.000,OR=10.036,95%CI为2.253-44.712).(3) Both GG,GA and AA genotype frequencies and G/A allele frequencies at position 100598 had no difference between conotruncal defect group,simple congenital heart disease gruop and normal control group.Conclusions:1,SNP at position 2857 C/G of TBX1 gene is associated with the susceptibility of TGA.G allele is susceptible allele to TGA.2,SNP at position 100308 G/A of HIRA gene is associated with the susceptibility of TOF and PTA.A allele is susceptible allele to TOF and PTA.3,SNPs at position 25983 C/G and 100598 G/A of HIRA gene have no association with conotruncal defects.