Cytogenetic and clinical characteristics of a case involving complete duplication of Xpter - + Xql 3 Syed

Received 5 July 1995 Revised version accepted for publication 23 October 1995 Abstract 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. Cytogenetically, it is described as a nonmosaic 46,X,psu idic(X)(ql3). Complete duplication ofXpter-Xql3 was confirmed by banded analysis and FISH probes for X centromere, Xp2l, XIST locus, and whole chromosome paints for X and Y. The abnormal X was always late replicating. Clinically, the patient was short statured, had primary amenorrhoea, and incomplete development ofsecondary sexual characteristics, but otherwise was phenotypically normal. There are no non-mosaic reported cases with complete duplication 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 ofXp (in presence of Xql3) there is a need to study more cases. (J Med Genet 1996;33:237-239)