Isochromosome consisting of terminal short arm and proximal long arm X in a girl with short stature.
A 16-year-old girl with short stature, short neck, shield chest, and cubitus valgus was studied. FISH analyses of her structurally altered X chromosome showed a der(X)- (wcpX+,TelXp/Yp++,SHOX++,STS++,KAL-, 37A12-,DXZ1+,XIST++,97L7++,300O13-,404F- 18-,417G15-,404F18-,140A-,TelXq/Yq-). These results, together with the high-resolution banding analysis, indicated her karyotype to be 46,X,der(X)(Xpter-->Xp22.3::Xq22.3--> cen-->Xq22.3::Xp22.3-->Xpter). The der(X) was an isochromosome, consisting of duplicated terminal short arms and duplicated proximal long arms. This in turn suggested that the chromosome was formed through pericentric inversion of an X chromosome, followed by isochromosome formation through sister chromatid exchange at Xp, close to the centromere. Replication R-banding analysis showed that the abnormal X chromosome was late replicating. Analysis of digestion patterns with a methylation-sensitive restriction endonuclease of the phosphoglycerate kinase 1 gene, located in Xq13.3, indicated that its inactivation patterns were completely skewed.
Uehara
S
S
Department of Obstetrics and Gynecology, Tohoku University School of Medicine, Sendai, Japan. uehara@ob-gy.med.tohoku.ac.jp
Hanew
K
K
Harada
N
N
Yamamori
S
S
Nata
M
M
Niikawa
N
N
Okamura
K
K
D000293:Adolescent; D002871:Chromosome Banding; D020732:Cytogenetic Analysis; D004303:Dosage Compensation, Genetic; D004392:Dwarfism / Q000235:genetics*; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D018404:Isochromosomes; D007621:Karyotyping; D012729:Sex Chromosome Aberrations; D014960:X Chromosome