Expression of size-polymorphic androgen receptor gene in uterine leiomyomaaccording to the number of cytosine, adenine, and guanine repeats in androgen receptor alleles

The amino terminus region of the androgen receptor (AR) gene in the X chrom osome involves the cytosine, adenine, and guanine (CAG) repeats. Random X c hromosome inactivation with AR alleles in individual cells occurs in female s. Therefore, probably either paternal or maternal single dominant polymorp hic AR mRNA must be expressed in neoplastic tissue originating from monoclo ne. 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 fou nd 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 e xpression, were found in individual nodes of uterine leiomyoma, although pa ternal and maternal AR mRNAs from normal uterine myometrium were consistent ly expressed as AR alleles. There was no significant specificity in activat ed AR alleles related to CAG numbers in individual nodes. Therefore, an ind ividual node of uterine leiomyoma might be formed from an independent monoc lonal uterine leiomyoma cell. Copyright (C) 2000 S. Karger AG, Basel.