Adjusting for patient age at surgery (years), tumor diameter at start of treatment (mm), parity (nulliparous or parous), total number of fibroids (one or multiple) and cohort (Sweden or Finland Myoma Study) resulted in a similar effect size, MED12 UFs having 4.6 times higher odds of treatment response compared to HMGA2 UFs (95% CI 1.33–16.1; P = 0.016; Supplementary Material, Fig. S3). This evidence concerns the gene HMGA2 and leiomyoma.