The amino terminus region of the androgen receptor (AR) gene in the X chromosome involves the cytosine, adenine, and guanine (CAG) repeats. Random X chromosome inactivation with AR alleles in individual cells occurs in females. Therefore, probably either paternal or maternal single dominant polymorphic AR mRNA must be expressed in neoplastic tissue originating from monoclone. This prompted us to determine the deviated numbers of CAG repeats in AR mRNA to understand the clonality of uterine leiomyoma. A solitary node of leiomyoma was macroscopically found in 7 cases, and multiple nodes were found in another 23 cases. Homozygous CAG repeats (22.0 +/- 2.3) in AR alleles were found in 5 of 30 cases, and either a large or small size of AR mRNA expression, were found in individual nodes of uterine leiomyoma, although paternal and maternal AR mRNAs from normal uterine myometrium were consistently expressed as AR alleles. There was no significant specificity in activated AR alleles related to CAG numbers in individual nodes. Therefore, an individual node of uterine leiomyoma might be formed from an independent monoclonal uterine leiomyoma cell.
Copyright 2000 S. Karger AG, Basel