Tetrasomy 9p mosaicism associated with a normal phenotype in two cases

Papoulidis I;Kontodiou M;Tzimina M;Saitis I;Hamid AB;Klein E;Kosyakova N;Kordass U;Kunz J;Siomou E;Nicolaides P;ORRU, SANDRO;Thomaidis L;Liehr T;Petersen MB;Manolakos E.

2012-01-01

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Abstract

Tetrasomy 9p is a rare chromosomal syndrome and about 30% of known cases exhibit mosaicism. Approximately 50 of the reported cases with tetrasomy 9p mosaicism show a characteristic facial appearance, growth failure, and developmental delay. However, 3 patients with mosaicism for isochromosome 9p and a normal phenotype have also been reported. We report 2 additional cases of clinically normal young females with tetrasomy 9p mosaicism, one of whom also exhibited X chromosome aneuploidy mosaicism leading to an overall of 6 different cell lines. STR analysis performed on this complex mosaic case indicated that the extra isochromosome was of maternal origin while the X chromosome aneuploidy was of paternal origin, indicating a postzygotic event.