True isochromosomes for Xp probably do not exist in a liveborn. We describe a rare case of complete Xp duplication and retention of the inactivation centre at Xql3. Cytogenetieally, it is described as a nonmosaic 46,X,psu idic(X)(ql3). Complete duplication of XpterXql3 was confirmed by banded analysis and FISH probes for X centromere Xp21 XIST locus and whole chromosome paints for X and Y. The abnormal X was always late replicating. Clinically, the patient was short statared had primary amenorrhoea and incomplete development of secondary sexual characteristics but otherwise was phenotypically normal. There are no nonmosaic reported cases with complete lupllcation of i(Xp) confirmed by FISH or molecular techniques. Those cases with partial duplication of Xp and presence of the inactivation centre share the traits of amenorrhoea and poor secondary sexual development. To develop a clinical profile of duplication of Xp (in presence of Xql3) there is a need to study more cases.
- I(Xp) duplication characteristics
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