Lars O. Vejerslev

Genetic analysis of repeated, biparental, diploid, hydatidiform moles

A woman presented with five consecutive pregnancies displaying molar morphology. In the fifth pregnancy, a non-malformed, liveborn infant was delivered. Genetic analyses (RFLP analysis, cytogenetics, flow cytometry) were performed in pregnancies II-V. It was demonstrated that these pregnancies originated in separate conceptions, all conceptuses were diploid, and all had maternally as well as paternally derived genetic markers. By cytogenetic analysis, aberrant heteromorphisms were noted; no other abnormalities were observed in chromosome structure or in DNA sequence. Many different causes for the abnormal development can be envisaged, environmental as well as genetic. To conform to current ideas of molar pathogenesis, it is suggested that the present conceptuses might have arisen from imbalances in imprinted genomic regions. This could be a consequence of uniparental disomy in critical regions generated by somatic crossing over. Alternatively, it could be caused by a malfunction in the generation or maintenance of imprinting.

Hydatidiform mole: genetic origin in polyploid conceptuses

SummaryThe origin of 29 polyploid conceptuses with villous cystic swelling was examined. One tetraploid specimen showed one maternal and three paternal contributions to the genome. Informative cytogenetic markers in 24 triploids were consistent with fertilization by dispermy. Analysis of cytogenetic markers indicated that polyspermy may account for essentially all polyploid conceptions with an excess of paternal to maternal chromosome complements. The origin of the genome was primarily demonstrated by the study of cytogenetic markers, while HLA determination and enzyme analysis were less informative.

Hydatidiform mole: Genetic markers in diploid abortuses with macroscopic willous 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 moles: Methods for culture and cytogenetic analyses

Placental tissue with macroscopic visible vesicles was processed for chromosome analysis. Enzymatic tissue dissociation, culture initiation in Changs medium, and final culture in a medium with high glucose content were used, which increased the success rate for karyotyping from 55% to 93%. Median culture time necessary for obtaining a karyotype decreased to about 1 week, irrespective of the chromosomal constitution. This was achieved in spite of increasing time for transportation. The metaphases obtained permitted detailed analysis of chromosomal polymorphisms. In 8 of 44 cases, the karyotype was established on short-term culture alone, which proved to be a valuable supplement in this study.

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.

Identification of triploidy by DA/DAPI staining of trophoblastic interphase nuclei

Combined staining of non-cultured interphase nuclei from hydatidiform moles with distamycin A and DAPI resulted in the presence of specific stained interphase bodies. A mean number of six interphase bodies was observed in moles with a diploid karyotype and a mean number of nine interphase bodies was observed in triploid moles. It is concluded that the interphase bodies are primarily due to specific staining of the large heterochromatic areas on chromosomes 1, 9 and 16. The method may permit a rapid measurement of the ploidy of non-cultured hydatidiform moles and identify partial, triploid moles.

Prenatal HLA-Determination

The present paper comprises the methods used for prenatal HLA-determination in a number of cases. When live cells are available, through a villous biopsy, amniocenthesis, or directly from an aborted fetus, a cytotoxic microtechnique is applied on cultured cells (cell culture: L.O. Vejerslev et al., this issue). After spontaneous or induced abortion a microabsorption method with the fetal tissue may be used.

Amniotic fluid cell and chorionic villi culture for prenatal HLA-determination

HLA-determination on placental or fetal tissue are of interest in Forensic Medicin as well as in Medical Genetics.I Forensic Medicine prenatal HLA-determination of the fetus supports a paternity diagnosis. In Medical Genetics one important aspect is prenatal diagnosis of congenital adrenal hyperplasia, as there is a close linkage between the HLA-B locus and a deficiency in 21-hydroxylase. Furthermore prenatal HLA-determination is of interest in relation to transplantation immunology.

Hydatidiform mole: a chromosomal search for a recessive mutation

In a search for minute structural aberrations indicating chromosomal regions of importance for the development of a hydatidiform mole, five diploid androgenetic moles and two partial dispermic moles were examined by high resolution banding technique. The absence of consistent aberrations suggests that either submicroscopical lesion(s) or the ratio of paternal to maternal chromosome complement(s) could be the decisive factor for molar development.