FISH analysis for apparently simple terminal deletions of the X chromosome: identification of hidden structural abnormalities.
We report on fluorescence in situ hybridization (FISH) analysis in 30 mosaic or nonmosaic females diagnosed as having apparently simple terminal X deletions by standard G-banding analysis. FISH studies for DXZ1, the Xp and Xq telomere regions, and the whole X chromosome painting were carried out for the 30 females, indicating rearranged X chromosomes with signal patterns discordant with terminal deletions in 6 cases: one dic(X)(DXZ1++) chromosome, two der(X)(qtel++) chromosomes, one Xq- (qtel+) chromosome, and two der(X)(ptel++) chromosomes. Additional FISH studies were performed for the 6 cases using probes defining 12 loci on the X chromosome, showing large Xp deletion and small Xp duplication in the dic(X)(DXZ1++) chromosome, partial Xp deletions and partial Xq duplications in the two der(X)(qtel++) chromosomes, an interstitial Xq deletion in the Xq- (qtel+) chromosome, and partial Xq deletions and partial Xp duplications in the two der(X)(ptel++) chromosomes. Clinical assessment of the 6 cases revealed tall and normal stature in the two mosaic cases with the der(X)(ptel++) chromosomes that were shown to be associated with SHOX duplication. The results suggest that unusual X chromosome rearrangements are often misinterpreted as simple terminal X deletions, and that FISH analysis is useful for precise structural determination and better genotype-phenotype correlation of the X chromosome aberrations.
Ogata
T
T
Department of Pediatrics, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. t-ogata@po.iijnet.or.jp
Matsuo
N
N
Fukushima
Y
Y
Saito
M
M
Nose
O
O
Miharu
N
N
Uehara
S
S
Ishizuka
B
B
D000328:Adult; D002648:Child; D002869:Chromosome Aberrations; D002871:Chromosome Banding; D002872:Chromosome Deletion; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D014960:X Chromosome / Q000235:genetics*