Cri du chat and Turner syndrome features in a newborn girl with an unbalanced 45,X,psu dic(5;X)(p15.2;p22.1) karyotype: FISH and replication banding studies.

A newborn girl with features of Turner and Cri du chat syndromes was found to have a pseudodicentric 5;X chromosome. Her karyotype was 45,X, psu dic(5;X)(p15.2;p22.1). The net result was monosomy for 5p15.2-pter and Xp22.1-pter. Fluorescence in situ hybridization (FISH) showed the Cri du chat region was deleted. Replication banding studies to assess the X-inactivation pattern found only the X portion of the pseudodicentric chromosome to be late replicating without any apparent spread of inactivation into chromosome 5 segment. There are only two cases reported with a dicentric X; autosome. In this paper, we compare the cytogenetics of the present case and those in the literature.