In CHMs, the overall methylation pattern was opposite to that observed in mature ovarian teratomas, but aberrant methylation was noted in some ICRs, including those of MEG3, H19, and NESPAS. In struma ovarii, the methylation pattern was comparable to that observed in mature ovarian teratomas, although one struma ovarii resembling follicular adenoma (case 2) showed aberrant methylation in some ICRs. The gene discussed is GNAS-AS1; the disease is ovarian teratoma.