Hydatidiform moles: methods for culture and cytogenetic analyses

Genetically different cell subpopulations in hydatidiform moles. A study of three cases by RFLP, flow cytometric, cytogenetic, HLA, and morphologic analyses

Most investigators find a good correlation between the morphologic and cytogenetic classification of hydatidiform moles (HM), but exceptions have been noted. We have examined three cases of HM, using chromosome marker analysis on cultured cells, human leukocyte antigen typing on cultured and uncultured tissue, and restriction fragment length polymorphism (RFLP) analysis and flow cytometry on uncultured cells. In one morphologically partial mole, only one cell population (triploid) was found and data obtained by the above-mentioned techniques were concordant. The other two moles, which were classified morphologically as complete, consisted of several cell subpopulations differing in DNA content. In both cases only one cell population was disclosed by cytogenetic investigation. In one case, the cytogenetic analysis indicated that the cultured cells were near triploid with paternal chromosomes exclusively, whereas RFLP analysis showed that maternal X chromosomal alleles were present in the mole. The present findings demonstrate that some HMs contain cellular subpopulations with differing DNA content. One explanation for discordance between cytogenetic and morphologic classification may thus be the detection of only one cell subpopulation when karyotyping.

Hydatidiform mole and HLA. III. HLA-antigen expression related to genomic origin

In 52 conceptuses with known genomic origin, HLA determination was performed on whole villi and/or stromal cell cultures. In 26 androgenetic, diploid conceptuses, one or two paternal HLA-A,B haplotypes were found; twenty-four triploid conceptuses with two paternal and one maternal chromosome sets showed either one maternal and one paternal haplotype or one/two paternal HLA-A,B haplotypes. Consequently, androgenesis could not be demonstrated by lack of maternal antigens alone. Concomitant expression of three HLA haplotypes was not seen. HLA-A2 was passed on to the conceptus, both in the genetic subgroups and in the entire series, more frequently than expected.

Hydatidiform mole and HLA. II. Compatibility between patient and conceptus

In 52 conceptuses with known genomic origin, the HLA types expressed on whole villi and/or stromal cell cultures were compared with the HLA types of the patients. No preference for either HLA compatibility or incompatibility was found for androgenetic and paternally derived triploid conceptuses as a whole. Heterozygous, androgenetic, conceptuses, however, showed a trend towards preferential incompatibility, which may be of importance for their apparent greater risk for trophoblastic tumour. HLA antibodies were found in 19.2% of the women, i.e. in the range reported for molar as well as non-molar pregnancies. Non-HLA antibodies reacting with lymphocytes of the spouse and/or cells from the conceptus were observed.

DNA-aneuploidy in 46,XX hydatidiform moles

The DNA content of single villous cell nuclei in 14 normal pregnancies and 21 androgenetic moles with a 46,XX karyotype was measured by flow cytometry. Six molar specimens showed a low mean DNA content close to that of normal villi, whereas, 15 specimens were characterized by a high mean DNA content due to a large fraction of nuclei in the triploid to tetraploid region. The latter group presumably corresponds to the previously described "type II" moles in which the DNA pattern resembled the pattern seen in invasive moles and choriocarcinoma.

Hydatidiform mole: cytogenetically unusual cases and their implications for the present classification

Unusual observations in hydatidiform moles are of clinical importance as well as of theoretical interest when the present subgrouping into partial or complete moles is evaluated, particularly in view of the more malignant potential of the latter. The purpose of the present review is to summarize, update, and evaluate information on moles with unusual karyotypes or origins. The important factor in the evolution of partial or complete moles appears to be the ratio of maternal to paternal chromosomes and not the ploidy of the tissue. Complete hydatidiform moles develop from androgenetic conceptions while partial hydatidiform moles develop from those conceptions in which the number of paternal sets of chromosomes exceeds the number of maternally derived sets. Rare cases inconsistent with this concept emphasize the value of examining morphologic features, cell ploidy, and genetic markers when one is attempting to classify hydatidiform moles.

Hydatidiform mole: genetic markers in diploid abortuses with macroscopic villous enlargement

In a series of diploid abortion specimens with gross villous enlargement the parental origin was determined by chromosomal heteromorphisms, HLA typing, and enzyme analysis. Diploid androgenesis was the mechanism in 33 cases; in 28 cases the most likely origin was by duplication of a haploid sperm after fertilization of an anucleated ovum, whereas heteromorphisms in five cases indicated a dispermic origin. In one macroscopically complete molar specimen all marker techniques applied indicated a normal conception. In two homozygous specimens a second cell line with both maternal and paternal contributions indicated a twin gestation, whereas, in four conceptuses twinning was suggested solely by HLA determination or ultrasound scan. The observation of a heterogeneous origin of diploid moles, as indicated by three marker systems studied simultaneously, emphasizes that additional information about the frequency of different types of molar conceptions may be obtained by this approach.

Hydatidiform mole: cytogenetic marker analysis in twin gestation. Report of two cases

A hydatidiform mole associated with a fetus proved to be the result of twin gestation. On microscopic examination of the placenta the case was classified as a partial hydatidiform mole. Chromosomal markers were, however, consistent with a normal conception and a mole of diploid androgenetic origin. Chromosome analysis of a morphologic complete molar specimen yielded two cell lines, one consistent with a normal conception and one with diploid androgenesis. Twinning in molar specimens must therefore be considered, regardless of macroscopic appearance. The prenatal diagnosis of a coexisting fetus and molar placenta poses a real clinical problem; analyses must distinguish between a partial mole plus a triploid fetus and a normal fetus occurring with a partial or a complete mole. The distinction is important for decisions made during pregnancy and may be of prognostic significance after termination. The usefulness of chromosome marker analysis in distinguishing between the various origins is pointed out, and it is suggested that twin pregnancy with hydatidiform mole is more frequent than its description in the literature would suggest.