Patau syndrome with long survival in a case of unusual mosaic trisomy 13

We report a 12-year-old patient with Patau syndrome, in whom two cell lines were present from birth,
one with total trisomy 13 due to isochromosome (13q), and one with partial trisomy 13.
A cytogenetic re-evaluation at 9 years of age brought to light in skin fibroblasts a third cell line, partially
monosomic for chromosome 13. The derivatives (13) present in the three cell lines were characterized
through fluorescence in situ hybridization (FISH) experiments with suitable probes; the results
suggested a sequence of rearrangements which beginning from an isochromosome (13q) could have led
to the other two derivatives. We report the clinical data at birth and at the age of 12; at this age pigmentary
lesions with phylloid pattern were noted. Cytogenetic findings of the chromosomal analyses on different
tissues, including skin fibroblasts from differently pigmented areas, are also reported.