Trisomy 12 mosaicism in phenotypically normal fetuses following prenatal detection

Wyandt, Herman E.; Maker, Thomas; Fisher, Nancy L.; Patil, Shivanand R.; Osella, Peter; Luthardt, Frederick W.; Kawada, Charles Y.; Williamson, Roger A.; Milunsky, Aubrey

doi:10.1002/pd.1970100904

Cited by 20 publications

(16 citation statements)

References 12 publications

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“…In our case, only metaphases with a normal karyotype were observed in the fetal lymphocytes. The present results, together with several other reports in the literature (e.g., von Koskull et al, 1989;Wyandt et al, 1990) clearly show that a normal chromosome complement in fetal lymphocytes does not exclude the existence of true fetal mosaicism in other tissues. In a recent review of rare trisomy mosaicism diagnosed in amniocytes, Hsu et al (1997), concluded that for less frequent trisomies, a cordocentesis is of limited value for further evaluation of true fetal mosaicism; except in cases of mosaicism for trisomy 8 and 9.…”

Section: Discussioncontrasting

confidence: 49%

Low-level mosaicism for both trisomy 15 and monosomy-X in amniotic fluid cells confirmed in fetal tissues

et al. 1998

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Section: Discussioncontrasting

confidence: 49%

Low-level mosaicism for both trisomy 15 and monosomy-X in amniotic fluid cells confirmed in fetal tissues

et al. 1998

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“…In others [Jensen et al, 1984;Wyandt et al, 1990;Park et al, 1991;Cartolano et al, 1993], the aborted fetuses had normal phenotypes or minor anomalies on examination/autopsy, but a minority of trisomic cells were observed in fetal organ culture.…”

Section: Discussionmentioning

confidence: 95%

“…At least six other cases of trisomy 12 detected prenatally led to therapeutic abortion [Jensen et al, 1984;Petrella and Hirshorn, 1990;Wyandt et al, 1990;Park et al, 1991;Cartolano et al, 1993;Bischoff et al, 1995]. It is difficult to draw conclusions about the phenotype of trisomy 12 mosaicism from these, as five of the six had no major malformations (only about half were autopsied) and most were associated with lowlevel mosaicism.…”

Section: Discussionmentioning

confidence: 95%

Trisomy 12 mosaicism confirmed in multiple organs from a liveborn child

et al. 2000

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This patient, in whom trisomy 12 mosaicism was confirmed in multiple organs, is the fifth case diagnosed postnatally and the first reported for whom a meiotic origin of the trisomy, maternal meiosis I, was determined. Mosaic aneuploidy was suspected because of pigmentary dysplasia, a frequent but non-specific finding in chromosomal mosaicism. The severe phenotype of this child, who died in infancy with a complex heart malformation, was probably a result of the high percentage of trisomic cells. Cytogenetic and interphase fluorescent in situ hybridization analyses showed a highly variable distribution of aneuploid cells in the nine tissues studied, from none in blood and ovary to 100% in spleen and liver. The trisomy arose meiotically with apparent post-zygotic loss of one of the chromosomes 12; uniparental disomy for this chromosome in the diploid cell line was excluded. The phenotype of the cases reported in living or liveborn individuals has been extremely variable, ranging from the present case, in which the child died in infancy with multiple malformations and pigmentary dysplasia, to a fortuitous finding in an adult studied for infertility. The variation in severity is probably determined by the proportion and distribution of the trisomic cells, which is linked to the timing of the non-disjunctional error.

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“…Moreover, a review of documented cases has revealed that the defect manifests across a spectrum from normal phenotype to Kartagner to severe heart defects and Potter Syndrome (Richer et al, 1977;Wyandt et al, 1990;DeLozier-Blanchet et al, 2000). The variations in the manifestations of trisomy 12 are more than likely due to the following factors: the inciting event that caused the genetic defect It is estimated that trisomy of the short arm of chromosome 12 has an incidence of 1/50,000 births.…”

Section: Anatomical Presentationmentioning

confidence: 97%

Anatomy of trisomy 12

et al. 2016

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Trisomy 12 is a rare aneuploidy and fetuses with this defect tend to spontaneously abort. However, mosaicism allows this anomaly to manifest itself in live births. Due to the fact that mosaicism represents a common genetic abnormality, trisomy 12 is encountered more frequently than expected at a rate of 1 in 500 live births. Thus, it is imperative that medical practitioners are aware of this aneuploidy. Moreover, this genetic disorder may result from a complete or partial duplication of chromosome 12. A partial duplication may refer to a specific segment on the chromosome, or one of the arms. On the other hand, a complete duplication refers to duplication of both arms of chromosome 12. The combination of mosaicism and the variable duplication sites has led to variable phenotypes ranging from normal phenotype to Potter sequence to gross physical defects of the various organ systems. This article provides a review of the common anatomical variation of the different types of trisomy 12. This review revealed that further documentation is needed for trisomy 12q and complete trisomy 12 to clearly delineate the constellation of anomalies that characterize each genetic defect. Clin. Anat. 29:633-637, 2016. © 2016 Wiley Periodicals, Inc.

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Trisomy 12 mosaicism in phenotypically normal fetuses following prenatal detection

Cited by 20 publications

References 12 publications

Low-level mosaicism for both trisomy 15 and monosomy-X in amniotic fluid cells confirmed in fetal tissues

Low-level mosaicism for both trisomy 15 and monosomy-X in amniotic fluid cells confirmed in fetal tissues

Trisomy 12 mosaicism confirmed in multiple organs from a liveborn child

Anatomy of trisomy 12

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