MED12 and uterine corpus leiomyoma: MED12 mutations in uterine leiomyomas were mostly identified in exon 2 and rarely in intron 1-exon 2 junction.[4, 7] All mutations were heterozygous in genomic DNA, and all of the transcripts were derived solely from the mutant MED12 alleles, suggesting its tumorigenesis role for LM development [8].