Severe phenotype resulting from an active ring X chromosome in a female with a complex karyotype: characterisation and replication study.
We report on the characterisation of a complex chromosome rearrangement, 46,X,del(Xq)/47,X,del(Xq),+r(X), in a female newborn with multiple malformations. Cytogenetic and molecular methods showed that the del(Xq) contains the XIST locus and is non-randomly inactivated in all metaphases. The tiny r(X) chromosome gave a positive FISH signal with UBE1, ZXDA, and MSN cosmid probes, but not with a XIST cosmid probe. Moreover, it has an active status, as shown by a very short (three hour) terminal BrdU pulse followed by fluorescent anti-BrdU antibody staining. The normal X is of paternal origin and both rearranged chromosomes originate from the same maternal chromosome. We suggest that both abnormal chromosomes result from the three point breakage of a maternal isodicentric idic(X)(q21.1). Finally, the phenotype of our patient is compared to other published cases and, despite the absence of any 45,X clone, it appears very similar to those with a 45,X/46,X,r(X) karyotype where the tiny r(X) is active.
Stavropoulou
C
C
INSERM U491, Faculté de Médecine Timone, Marseille, France.
Mignon
C
C
Delobel
B
B
Moncla
A
A
Depetris
D
D
Croquette
M F
MF
Mattei
M G
MG
D000015:Abnormalities, Multiple / Q000235:genetics*; D002869:Chromosome Aberrations; D002872:Chromosome Deletion; D004303:Dosage Compensation, Genetic; D005260:Female; D018392:Genomic Imprinting; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007231:Infant, Newborn; D018404:Isochromosomes; D007621:Karyotyping; D008297:Male; D010375:Pedigree; D010641:Phenotype; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D012303:Ring Chromosomes; D014157:Transcription Factors / Q000235:genetics; D014960:X Chromosome
D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D014157:Transcription Factors; C077885:XIST non-coding RNA