Mosaic tetrasomy 8q: Inverted duplication of 8q23.3qter in an analphoid marker

Reddy, Kavita S.; Sulcova, Vladimira; Schwartz, Stuart; Noble, Julie E.; Phillips, Jeffrey B.; Brasel, Jo Anne; Huff, Kenneth R.; Lin, Henry J.

doi:10.1002/(sici)1096-8628(20000501)92:1<69::aid-ajmg12>3.0.co;2-o

Cited by 18 publications

(2 citation statements)

References 45 publications

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“…The novel position of CENP-C and absence of alpha satellite DNA in the abnormal X chromosome defined a neocentromere, which also explains its mitotic stability. The mosaicism observed in the karyotype of our patient is very likely a consequence of gradual formation, stabilization, and functioning of the neocentromere after several post-fertilization cell divisions, during which the iso(Xq) may be lost in a proportion of cells [14,26]. …”

Section: Discussionmentioning

confidence: 99%

Neocentric X-chromosome in a girl with Turner-like syndrome

et al. 2012

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BackgroundNeocentromeres are rare human chromosomal aberrations in which a new centromere has formed in a previously non-centromeric location. We report the finding of a structurally abnormal X chromosome with a neocentromere in a 15-year-old girl with clinical features suggestive of Turner syndrome, including short stature and primary amenorrhea.ResultG-banded chromosome analysis revealed a mosaic female karyotype involving two abnormal cell lines. One cell line (84% of analyzed metaphases) had a structurally abnormal X chromosome (duplication of the long arm and deletion of the short arm) and a normal X chromosome. The other cell line (16% of cells) exhibited monosomy X. C-banding studies were negative for the abnormal X chromosome. FISH analysis revealed lack of hybridization of the abnormal X chromosome with both the X centromere-specific probe and the “all human centromeres” probe, a pattern consistent with lack of the X chromosome endogenous centromere. A FISH study using an XIST gene probe revealed the presence of two XIST genes, one on each long arm of the iso(Xq), required for inactivation of the abnormal X chromosome. R-banding also demonstrated inactivation of the abnormal X chromosome. An assay for centromeric protein C (CENP-C) was positive on both the normal and the abnormal X chromosomes. The position of CENP-C in the abnormal X chromosome defined a neocentromere, which explains its mitotic stability. The karyotype is thus designated as 46,X,neo(X)(qter- > q12::q12- > q21.2- > neo- > q21.2- > qter)[42]/45,X[8], which is consistent with stigmata of Turner syndrome. The mother of this patient has a normal karyotype; however, the father was not available for study.ConclusionTo our knowledge, this is the first case of mosaic Turner syndrome involving an analphoid iso(Xq) chromosome with a proven neocentromere among 90 previously described cases with a proven neocentromere.

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Section: Discussionmentioning

confidence: 99%

Neocentric X-chromosome in a girl with Turner-like syndrome

et al. 2012

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“…Neocentromeric marker chromosomes have been described in individuals where the marker chromosomes are non-mosaic but also in individuals where there is mosaicism. So far, at least 38 analphoid markers originating from different and apparently unique parts of the genome have been reported (Reddy et al, 2000). In this article, we report the finding of an analphoid marker chromosome in cultured amniocytes and lymphocytes and its characterisation with (micro)FISH.…”

Section: Introductionmentioning

confidence: 85%

Mosaic trisomy (8)(p22 ? pter) in a fetus caused by a supernumerary marker chromosome without alphoid sequences

et al. 2005

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Mosaic inv dup(8p) marker chromosome with stable neocentromere suggests neocentromerization is a post-zygotic event

et al. 2001

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Marker chromosomes containing active human neocentromeres have been described in individuals where the chromosomes are non-mosaic, suggesting that they are mitotically stable, but also in individuals where there is mosaicism, raising the possibility of neocentromere instability. We report two independently ascertained individuals who are mosaic for a supernumerary marker chromosome, shown by reverse chromosome painting to have an 8p origin, resulting in mosaicism for tetrasomy 8p23.1-->pter in the patient. The markers have a primary constriction but show no detectable centromeric alpha-satellite DNA. The marker in Patient 1 demonstrated no centromere protein CENP-B binding, but associated with nine different functionally critical centromere proteins. Investigation of peripheral blood lymphocytes from this patient on five separate occasions over a 13-year period showed 23-46% mosaicism for the marker chromosome with no decrease in incidence. In vitro investigation of primary and secondary sub-clones of a lymphoblast cell line derived from the patient demonstrated 100% stability of the marker chromosome indicating that neocentromere instability is unlikely to be responsible for the mosaicism in the patient. This and other available data support a general model of neocentromerization as a post-zygotic event, irrespective of whether the supernumerary chromosome fragment has arisen during meiosis or post-fertilization at mitosis.

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Mosaic tetrasomy 8q: Inverted duplication of 8q23.3qter in an analphoid marker

Cited by 18 publications

References 45 publications

Neocentric X-chromosome in a girl with Turner-like syndrome

Neocentric X-chromosome in a girl with Turner-like syndrome

Mosaic trisomy (8)(p22 ? pter) in a fetus caused by a supernumerary marker chromosome without alphoid sequences

Mosaic inv dup(8p) marker chromosome with stable neocentromere suggests neocentromerization is a post-zygotic event

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