A woman with an apparent non-mosaic 45,X delivered a 46,X,der(X) liveborn female |
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Authors: | G. Palka G. Calabrese L. Stuppia P. Guanciali Franchi E. Morizio R. Peila A. Antonucci |
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Affiliation: | Istituti di Biologia e Genetica e;di Morfologia Umana Universitádi Chieti;Istituto di Citomorfologia Normale e Patologica del C.N.R. Chieti, Italy |
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Abstract: | A liveborn female with a phenotype suggestive of Down syndrome is reported. Cytogenetic lymphocyte analysis showed a 46,X der(X) karyo-type. Fluorescence in situ hybridization (FISH) with a biotinylated probe specific for chromosome 21 showed no signal on the der(X). This marker was homogeneously painted using a specific probe for X chromosome. In addition, FISH analysis detected telomeres on the rearranged X. Therefore, the proband's karyotype was revaluated as 46,X,del(X) (pter p22.2::p11.3 qter). Cytogenetic analysis of 150 lymphocytes in the mother disclosed a homogeneous 45,X karyotype. FISH analysis of interphase nuclei using the X chromosome painting probe showed two domains of different sizes in 0.8% of cells. This led us to study further metaphases in the mother. In one out of 450 metaphases scored, after FISH with the X chromosome painting probe, the del(X) was observed, confirming that the rearranged X chromosome found in the newborn had segregated from a 45,X/46,X,del(X) mother. |
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Keywords: | fertility FISH sex chromosome mosaicism X chromosome deletion |
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