Specific chromosomal abnormalities, such as del(7q), t(12;14), 12 trisomy, or the rearrangement of 6p, are seen in approximately 30% of uterine leiomyomas despite their benign status. We investigated the association between the shrinkage of uterine leiomyomas treated with a GnRH agonist and the interstitial deletion of chromosome 7q, which is one of the most common chromosomal abnormalities in uterine leiomyomas. This study covered 29 women with uterine leiomyomas who were treated with a GnRH agonist before surgery. The volume of the largest myoma nodule was measured by means of MRI before and at 12 weeks after the beginning of GnRH agonist treatment, and the percentage of the reduction in volume was calculated. Genomic DNA was extracted from leiomyoma tissue and peripheral blood, and amplified by PCR using fluorescently-tagged oligonucleotide primers of twelve microsatellite loci on chromosome 7. The PCR products were analyzed for loss of heterozygosity (LOH) using an automated fluorescent DNA sequencer. Of the 29 informative tumors, five (17%) showed LOH with deletion of the common region, D7S491. The mean percentages of the reduction in volume of the largest myomas with LOH or without LOH were 32±13 and 18±58%, respectively (not significant). One tumor showing interstitial deletion of both alleles (homo-deletion) reduced in volume by 19%. Another tumor showing an extraband increased in volume by 13%. Although tumor specific chromosomal deletion suggested the existence of tumor suppressor genes in this region, there was no significant association between the shrinkage of uterine leiomyomas treated with a GnRH agonist and the interstitial deletion of chromosome 7q.

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