Apparent neotelomere in a 46,X,del(X)(qterâp11.2:)/46,X,rea(X)(qterâp11.2::q21.2âqter) novel mosaicism: review of 34 females with a recombinant-like dup(Xq) chromosome.
Genet Test Mol Biomarkers
; 15(10): 727-31, 2011 Oct.
Article
em En
| MEDLINE
| ID: mdl-21651320
ABSTRACT
A 26-year-old woman with secondary amenorrhea and turneroid stigmata was found to have a 46,X,rea(X)(qterâp11.2q21.2âqter)/46,X,del(X)(qterâp11.2) mosaicism in 101 G-banded metaphases (71 and 30, respectively). The mother's karyotype was normal (the father was already deceased). A fully skewed inactivation of both abnormal X-chromosomes was documented in RBG-banded metaphases and by means of the HUMARA assay. In addition, the latter revealed that the involved X-chromosome was the paternal one. The patient's secondary amenorrhea and turneroid stigmata can reliably be ascribed to her nearly complete Xp deletion present in all cells. Thus, this observation is consistent with the well-known gradation of ovarian function depending on the Xp deletion size. We assume that the first event was an intrachromosome recombination during paternal meiosis between paralogous sequences at Xp11.2 and Xq21.2, which resulted in a fertilizing rea(X) spermatozoid. Early in embryogenesis, the rea(X) dissociated at the Xp11.2 junction point to originate the del(X), which in turn was healed by the de novo addition of telomeric repeats (the acentric Xq21.2âqter segment was lost in the process). The reverse sequence appears unlikely because it implies that the del(X) chromosome was healed only after it undergone a postzygotic interchromatid recombination and apposite segregation required to obtain the rea(X) clone. The present observation further expands the cytogenetic heterogeneity in Turner syndrome and may represent another instance of a terminal deletion healed by the de novo addition of telomeric repeats.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Recombinação Genética
/
Deleção Cromossômica
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Cromossomos Humanos X
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Duplicação Cromossômica
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Mosaicismo
Tipo de estudo:
Etiology_studies
/
Incidence_studies
/
Observational_studies
/
Risk_factors_studies
Limite:
Adult
/
Female
/
Humans
Idioma:
En
Revista:
Genet Test Mol Biomarkers
Assunto da revista:
BIOLOGIA MOLECULAR
/
GENETICA
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
México