A woman with an apparent non-mosaic 45,X delivered a 46,X,der(X) liveborn female.
A liveborn female with a phenotype suggestive of Down syndrome is reported. Cytogenetic lymphocyte analysis showed a 46,X der(X) karyotype. 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 reevaluated 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.
Palka
G
G
Istituti di Biologia e Genetica, Umana Universitá di Chieti, Italy.
Calabrese
G
G
Stuppia
L
L
Guanciali Franchi
P
P
Morizio
E
E
Peila
R
R
Antonucci
A
A
D002478:Cells, Cultured; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007231:Infant, Newborn; D007621:Karyotyping; D009006:Monosomy; D009030:Mosaicism; D010641:Phenotype; D012729:Sex Chromosome Aberrations; D014960:X Chromosome