ometrial tissues. KRT19 protein levels in 8 subjects were lower in leiomyoma than myometrial tissues, and only 1 subject had higher KRT19 protein levels in leiomyoma compared with myometrial tissues. All protein studies were performed with 69 new pairs of matched samples not previously used 
in the microarray experiments; 5 subjects were African American and 4 subjects were Caucasian. Overall, western blots showed that KLF11, DLEC1 and KRT19 . Protein levels in leiomyoma tissues were significantly lower compared with matched normal myometrial tissues. Fold change was calculated as mean mRNA expression microarray value for leiomyoma relative to normal myometrium. Discussion Recent evidence suggests that DNA is differentially methylated in uterine leiomyoma versus adjacent normal myometrial tissue; however, these findings are predominantly reported in small studies and analysis of individual candidate genes such as ESR1, which has been shown to be hypomethylated in leiomyomas. We particularly paid attention to the ESR1 gene, but we did not observe any differential ” DNA methylation patterns between leiomyoma and myometrium. Hypomethylation of ESR1 in leiomyoma was reported using a group of Japanese subjects; thus the difference between our findings and theirs could be attributed to racial differences. Similar racial differences have also been reported for the aromatase mRNA levels and promoter usage in uterine leiomyomas. More recently published reports have attempted to demonstrate differential DNA methylation in leiomyomas; one study examined differences across the X chromosome in a single subject supporting the concept of epigenetic regulation in uterine leiomyoma. However, the other study was insufficient to identify differences in DNA methylation, which could be due to the small number of samples investigated. Fold change was calculated as mean mRNA expression microarray value for leiomyoma relative to normal myometrium. doi:10.1371/journal.pone.0033284.t003 wide analysis of differential DNA-methylation and mRNA expression in uterine leiomyoma and adjacent normal myometrial tissues from 18 matched pairs, all from African American subjects to limit biological heterogeneity, and avoid epigenetic variations among ethnic groups. The following real-time RT-PCR validation of mRNA expression and bisulfite sequencing validation of DNA methylation of these genes were performed on both a subset of the original African American samples and additional new samples from Caucasian subjects. Additionally, in vitro cultured experiments utilized primary cells from both ethnic groups. We have not observed any apparent differences with respect to the 3 studied genes between samples from African- and Caucasian-American subjects suggesting that the findings may be applicable to both ethnic groups. This conclusion, however, should be taken with some caution due to the low number of Caucasian subjects. Further studies are needed to make a more definitive conclusion. Our study confirms the link between epigenetic DNA modifications and gene expression in uterine leiomyomas, by September 2026