Genetic Association Between The Polymorphism Of PR, EGFR Gene And Uterine Leiomyoma

Uterine leiomyoma is the highest disease incidence of gynecologic humor and the cause of uterus excision. The incidence is increasing and becoming younger year by year. But the cause and mechanisms is not illuminated .Several lines of evidence from cytogenetics and genetic epidemiological data suggest that genetic factors are likely to play an essential role in the developing of uterine leiomyoma. Uterine leiomyoma is not a simple Mendelian disease, but it is very likely to be a complex disease with a polygenic mechanism.The studies of uterine leiomyoma on gene chip technique and candidate gene have acquired many positive results, however, these results with poor repeats. So far, the major and specific susceptibility genes leading to uterine leiomyoma remains unidentified.ObjectiveTo investigate a genetic association between the polymophism of progesterone receptor ( PR )gene, epidermal growth factor receptor(EGFR) gene and uterine leiomyoma, by detecting SNPs of PR and EGFR genes with the bioinformatics and the molecular genetics. The present study tried to reveal the predisposing genes and molecular genetic mechanism for uterine leiomyoma. Methods The subjects were 165 with uterine leiomyoma patiens and 157 healthy women of Han descent, consisting of the age between 30 and 50. These patients originally came from the first affiliated hospital of Jilin university during the period between Sep, 2005 and Dec, 2006.All the subjects gave written informed consent for the genetic analysis and taken blood from peripheral vein. Genomic DNA used for PCR amplification was extracted from the whole blood sample using a DNA extraction kit. We screened polymorphic SNPs using Polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) analysis based on the SNP map of the genes for PR and EGFR. We elected 3 SNPs including SNP1 (rs11224567) at PR locus, SNP2 (rs6944695) and SNP3 (rs12056121) in EGFR locus.The Hardy-Weinberg equilibrium for genotypic distributions was tested using the chi-square (χ2) goodness-of-fit test. The Statistical software SPSS12.0 program was applied to test allelic association for a single locus. The conditional test was performed with the UNPHASED program and used to test the combined effect of distinct loci on the disease by conditioning on allele ( COA ) or by conditioning on genotype ( COG ).Results( 1 ) The analytic results of questionaire dataThe analytic results showed that the mean of age of 165 uterine leiomyomas patiens was 42.3±6.7 years old, the mean of age of 157 healthy women was 40.6±10.4 years old, There were no difference between the case and control ( t=1.753, P=0.081)。( 2 ) Hardy-Weinberg equilibrium testThe Hardy–Weinberg equilibrium for genotypic distributions was tested using the chi-square (χ~2 ) goodness-of-fit test. The goodness-of-fit test showed that the genotype frequency distributions of these three SNPs were not deviated from the Hardy-Weinberg equilibrium in both the patient group and the control group ( P > 0.05 ).( 3 ) Analysis of the effect of single one lociWith Statistical software SPSS, the chi-square (χ~2 ) test handled the data on genotype and allele frequencies. There were no significant differences of the distribution of allege frequencies and genotype in the SNP1 loci of PR gene between the case and control groups(χ~2=0.908, P=0.635;χ~2=0.966, P =0.326).SNP3 loci of EGFR gene was associated with uterine leiomyomas(χ~2=25.144, P=0.000;χ~2=21.969, P=0.000).But we can′t see the difference in the SNP3 loci of EGFR gene(χ~2=0.562, P=0.755;χ~2=0.455, P=0.500).( 4 )Analysis of the combined effect of distinct lociThe conditional test was used to test the combined effect of distinct loci on the disease by COA or by COG. The COA and COG test showed the disease association for SNP1 (PR) combined with SNP2 (EGFR).The COA test also showed that SNP2 (EGFR) combined with SNP3 (EGFR) associated with uterine leiomyoma. This indicated that there were more than one SNPs associated with uterine leiomyoma in EGFR genes.ConclusionsAccording to the above-mentioned analytic results, we can reach the following conclusions:(1)The findings of this study suggested that PR gene may not play an important part in uterine leiomyoma development.(2)There was a genetic association between the SNP2 loci in EGFR gene and uterine leiomyoma, T allele frequencies and T/T genotype distribution were concerned with uterine leiomyoma.(3)The SNP3 loci in EGFR gene wasn't relate to uterine leiomyoma(.4) The combined effect of SNP1 and SNP2 was associated with uterine leiomyoma.In a word, these findings thoroughly suggested that PR gene and EGFR gene associate with uterine leiomyoma, which support the mechanisms of uterine leiomyoma powerfully. The genetic association of combined effect of distinct loci with uterine leiomyoma supported the polygenic theory of complex disease.These findings are very important for elucidating the genetic mechanisms of uterine leiomyoma at a molecular level, and also for the development of genetic diagnosis, new drugs for the treatment of the illness and prediction of uterine leiomyoma risk.