Confined blood chimerism in monochorionic dizygous (MCDZ) twins

Walker, Susan P.; Meagher, Simon; White, Susan

doi:10.1002/pd.1670

Cited by 39 publications

(39 citation statements)

References 9 publications

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“…In cases of monochorionic twins with discordant karyotypes, one or both twins may exhibit mosaicism, possessing cells of diverse genetic consitution but derived from a single zygote, as seen in Twin B. Chimerism, defined as an organism made up of cells derived from more than one zygote, has been documented in rare cases of dizygous monochorionic twin gestation 14 . Monochorionic placentation is typically associated with shared circulation between twins.…”

Section: Discussionmentioning

confidence: 99%

Monozygotic twins discordant for trisomy 13

et al. 2012

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Section: Discussionmentioning

confidence: 99%

Monozygotic twins discordant for trisomy 13

et al. 2012

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“…Another IVF pregnancy with transfer of two embryos [Walker et al, 2007] resulted in MC male fetuses who were only diagnosed as DZ because buccal cells were analyzed as part of a research protocol. There was blood chimerism.…”

Section: Article American Journal Of Medical Genetics Part C (Seminarmentioning

confidence: 99%

Non‐identical monozygotic twins, intermediate twin types, zygosity testing, and the non‐random nature of monozygotic twinning: A review

Machin

2009

American J of Med Genetics Pt C

138

102

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Monozygotic twins (MZ) are rarely absolutely “identical.” This review discusses the types of genetic/epigenetic and prenatal environmental post‐zygotic mechanisms that cause discordance within such twin pairs. Some of these mechanisms—ranging from heterokaryotypia to skewed X‐chromosome inactivation—may cause extreme discordance, but these extremes are merely the more emphatic examples of discordance that, to some degree, underlies the majority of MZ twin pairs. Because of the entrenched misconception that MZ twins are necessarily identical, many MZ twin pairs are mistakenly designated as dizygotic (DZ). Clinical benefits to accurate zygosity determination include correct solid organ transplantation matching, if one twin requires donation for a non‐genetically mediated disease; the opportunity of preventive management for disorders that do not manifest synchronously; and better counseling to parents regarding their individually unique, and often psychologically puzzling, twin offspring. In twin pairs with complex and confusing biological origins, more detailed zygosity testing may be required. For example, intermediate trigametic and tetragametic chimeric dizygotic twins are reviewed, some of whom are, nevertheless, monochorionic (MC). Because of inter‐fetal vascular anastomoses in MC twins, genetic results from blood samples may not accurately reflect discordance in solid organs. Previously, it was thought that MZ twinning was some sort of embryological fluke. However, familial monozygotic twinning is more common than suggested by the literature. Seven new families are presented in an accompanying paper. Despite the difficulties and dangers of twin pregnancy (especially so for MC twins), human twinning persists, and continues to both challenge and fascinate parents, clinicians and geneticists. © 2009 Wiley‐Liss, Inc.

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“…Several monochorionic dizygotic twins have been reported, almost exclusively cases of assisted reproduction (ART). 20 In the literature, a large number of BWS twins have been described. Remarkably, the great majority of BWS twins are MZ, but they are discordant, that is, one twin presents with BWS, whereas the other is unaffected (though an unaffected twin may have some features of the disease).…”

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confidence: 99%

Lessons from BWS twins: complex maternal and paternal hypomethylation and a common source of haematopoietic stem cells

et al. 2009

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The Beckwith -Wiedemann syndrome (BWS) is a growth disorder for which an increased frequency of monozygotic (MZ) twinning has been reported. With few exceptions, these twins are discordant for BWS and for females. Here, we describe the molecular and phenotypic analysis of 12 BWS twins and a triplet; seven twins are MZ, monochorionic and diamniotic, three twins are MZ, dichorionic and diamniotic and three twins are dizygotic. Twelve twins are female. In the majority of the twin pairs (11 of 13), the defect on chromosome 11p15 was hypomethylation of the paternal allele of DMR2. In 5 of 10 twins, there was additional hypomethylation of imprinted loci; in most cases, the loci affected were maternally methylated, but in two cases, hypomethylation of the paternally methylated DLK1 and H19 DMRs was detected, a novel finding in BWS. In buccal swabs of the MZ twins who share a placenta, the defect was present only in the affected twin; comparable hypomethylation in lymphocytes was detected in both the twins. The level of hypomethylation reached levels below 25%. The exchange of blood cells through vascular connections cannot fully explain the degree of hypomethylation found in the blood cell of the non-affected twin. We propose an additional mechanism through which sharing of aberrant methylation patterns in discordant twins, limited to blood cells, might occur. In a BWS-discordant MZ triplet, an intermediate level of demethylation was found in one of the non-affected sibs; this child showed mild signs of BWS. This finding supports the theory that a methylation error proceeds and possibly triggers the twinning process.

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Confined blood chimerism in monochorionic dizygous (MCDZ) twins

Cited by 39 publications

References 9 publications

Monozygotic twins discordant for trisomy 13

Monozygotic twins discordant for trisomy 13

Non‐identical monozygotic twins, intermediate twin types, zygosity testing, and the non‐random nature of monozygotic twinning: A review

Lessons from BWS twins: complex maternal and paternal hypomethylation and a common source of haematopoietic stem cells

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