Study On Association Between Estrogen Receptor Polymorphisms And Uterine Leiomyoma

Uterine leiomyoma is common benign tumor in female genital organs and there is about 20%-30% of the females in reproductive life being subjected to this disease.The tumor is dependent on gonadal hormones from ovaries, with estrogen playing important roles in the course of onset and development of this tumor.The biological effect of estrogen is mediated by their receptors (ERαand ERβ). Upon combination with their ligands, with the participation of aseries of coregulators, these receptors regulate the expression of target genes, by interacting as transcription regulators with the hormone response elements in target genes.Due to the importance of estrogen in the pathogenesis of uterine leiomyoma, meanwhile, in the sequences of these genes encoding ER, there are a lot of polymorphisms associated with the corresponding phenotype of hormone response systems.ObjectiveWe take ERαand ERβas candidate genes, to study the distribution of Single Nucleotide Polymorphisms (SNPs) in these genes and its association with the pathogenesis of uterine leiomyoma. The present study tried to reveal the predisposing genes and molecular genetic mechanism for uterine leiomyoma.MethodsA case-control study was conducted in Changchun, China. 170 normal women as a control and 167 women cases with uterine leiomyoma were recruited from NO.1 Hospital of Jilin University. The cases were considered to be uterine leiomyoma patients diagnosed by imageology diagnosis and (or) pathology diagnosis , the controls were considered to be patients with uterine leiomyoma excluded and healthy individual. Both patients and controls were excluded the hormone-related diseases and had not use hormones in 3 months, the age of them was from 30 to 50. All the subjects gave written informed consent for the genetic analysis and taken 5ml blood from peripheral vein. Genomic DNA used for PCR amplification was extracted from the whole blood sample using a DNA extraction kit (Ningbo, China).Four SNPs present in the ERαand ERβwere chosen by accessing the databases at http://www.ncbi.nlm.nih.gov/, http://www.ncbi.nlm.nih.gov/SNP and http://snp.cshl.org/ web sites. The candidate SNPs included SNP1(rs9322346), SNP2(rs722209) present in the ERαlocus, and SNP3(rs1256064), SNP4(rs1256049) in the ERβlocus, respectively.The variations of DNA fragments of ERαand ERβwere screened by polymerase chain reaction- restriction fragment length polymorphism(PCR-RFLP).The Hardy–Weinberg equilibrium for genotypic distributions was tested using the chi-square (χ~2) goodness-of-fit test. Theχ~2 test was used to test the association between the SNPs of ERαand ERβgenes and uterine leiomyoma by SPSS12.0. The conditional test was performed with the UNPHASED program (Frank Dudbridge, MRC Human Genome Mapping Project Resource Centre, Hinxton, UK). The conditional test was used to test the combined effectof distinct loci on the disease by conditioning on allele (COA) or by conditioning on genotype (COG).Results(1) The analytic results of The H-W equilibriumTheχ~2 goodness-of-fit test showed that the genotypic distributions of all 4 SNPs were not deviated from the H-W equilibrium (P>0.05), and thus this sample pool was suitable for the genetic analysis.(2) The analytic results of SNPs of ERαand ERβand uterine leiomyomaComparing women with uterine leiomyoma and controls, we demonstrated no statistical significant differences of allele frequency and genotype distribution for the SNP1 and SNP2 polymorphism (χ~2 =4.169, P=0.008;χ~2 =9.729, P=0.154 andχ~2 =1.132, P=0.568χ~2 =0.882, P=0.348 respectively). But, It showed statistical significant differences of allele frequency and genotype distribution for the SNP3 polymorphism (χ~2 =6.933, P=0.031andχ~2 =6.212, P=0.013). for the SNP3 polymorphism we found a significant difference concerning allele frequency (χ~2 =4.083, P=0.043). However, for the genotype distribution, only borderline significance was observed (χ~2 =4.622, P=0.099).(3) The analytic results of the combined effect of distinct lociBoth the COA and COG test showed a disease association for SNP1-SNP3 (χ~2 =9.753, P=0.008;χ~2 =9.663, P=0.008), SNP2-SNP3 and (χ~2 =7.920, P=0.019;χ~2 =8.760, P=0.033) ,SNP1-SNP2-SNP3(χ~2 =13.499, P=0.019;χ~2 =13.610, P=0.034) with uterine leiomyoma.ConclusionsTaken together, the SNP1 and SNP2 of ERαgene were not associated with uterine leiomyoma; SNP3 and SNP4of ERβwere associated with uterine leiomyoma.SNP3 may be the predisposing SNP of uterine leiomyoma in a Han population and Women with T/T alleles are the predisposing persons of uterine leiomyoma; meanwhile, SNP1 and SNP2 of ERαgene combined with SNP3 increase the risk of uterine leiomyoma.