As published in Cancer Genetics and Cytogenetics Vol. 98, No.1, pp. 69-74, 1997

The del(7q) subgroup in uterine leiomyomata: genetic and biologic characteristics

Further evidence for the secondary nature of cytogenetic abnormalities in the pathobiology of uterine leiomyomata

 Y. Polly Xing, W. Lee Powell, and Cynthia C. Morton
From the Department of Pathology, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts

Rearrangement of 7q represents one of the major cytogenetic subgroups in uterine leiomyomata, the most common tumors arising in females. Herein we report cytogenetic analysis on a series of 22 cases of uterine leiomyomata with 7q abnormalities, and describe observations regarding tumor size and maintenance of the tumor cells in culture. We discuss the frequent finding of mosaic tumors containing both cells with the 7q rearrangement and karyotypically normal cells. Clonality studies of three mosaic cases reveal nonrandom X chromosome inactivation substantiating prior findings suggesting the secondary nature of chromosome aberrations in these tumors. Genes mapped in 7q22 and those identified in the pathobiology of other uterine leiomyomata subgroups are discussed in addition to a perspective on the role of the 7q22 leiomyomata gene.

Table 1. Karotypes, sizes and volumes of twenty-two uterine leiomyomata with chromosome 7 aberrations

^a,b,d,f, Karotypes of a,b and e previously reported in references [14], [10], and [12] respectively.
^c Patients pretreated with a gonadotropin releasing hormone analog prior to surgery and excluded from the analysis of size and volume
^e Cases not meeting the formal ISCN classification as mosaics; however, in this context the single cell of different karotype is believed to be relevant.

Table 2. Karotypes in serial passages of del(7q) cultures

Figure 1.Clonality assay by PCR amplification of the HUMARA locus with (+) and without (-) prior HhaI restriction digestion. For all three cases, both alleles were present prior to HhaI digestion. After digestion, only one of two alleles can be seen in samples ST94-145 and ST94-260 and one predominant band can be seen in sample ST94-193, consistent with a nonrandom X chromosome inactivation in these leiomyoma tissues.