FISH analysis helps identify low-level mosaicism in Ullrich-Turner syndrome patients.

PURPOSE

To search for X or Y chromosome mosaicism in 45,X individuals using fluorescent in situ hybridization (FISH).

METHODS

From our series of 53 Ullrich-Turner syndrome patients, we used interphase FISH to evaluate the 19 who had an apparently nonmosaic 45,X karyotype with G-banding.

RESULTS

Of those 19 patients, mosaicism was detected in seven (37%), five patients had an XX line, one had a monocentric isochromosome X, and one had a dicentric isochromosome X. No Y chromosome mosaic was identified.

CONCLUSION

FISH analysis is a sensitive and cost-effective adjunct to karyotype analysis to identify sex chromosome mosaicism in UTS.