Tetraploid-diploid mosaicism in a patient with pigmentary anomalies of hair and skin: a new dermatologic feature

Tetraploid-diploid mosaicism in humans is exceedingly rare. We present an 11-year-old boy with tetraploid-diploid mosaicism and coexistent hair hypopigmentation with skin hypo- and hyperpigmentation. This case expands the current literature as we are not aware of previous documentation of this unique combination of pigmentary anomalies.

Application of touch FISH in the study of mosaic tetraploidy and maternal cell contamination in pregnancy losses

PURPOSE

karyotype is a well established technique in the study of spontaneous miscarriages but is associated with selective overgrowth of maternal cells and other culture artefact (spp) such as tetraploidy, which could mask the true karyotype of the conceptus.

METHODS

328 cases of pregnancy losses were studied by karyotype and Multiplex Ligation Dependent Probe Amplification technique. Touch FISH performed in non-cultured cells was used to evaluate the ploidy complement and sex discrepancies using centromeric probes for chromosomes X, Y and 18.

RESULTS

touch FISH confirmed 13 cases of maternal contamination, identified a triploidy and a monosomy X. True tetraploidy was confirmed in 7/14 cases studied.

CONCLUSION

touch FISH protocol is extremely accurate in the distinction of genuine mosaicism from tissue culture artifacts namely in cases with suspicion of tetraploidy and can be used to confirm maternal cell contamination in cases with sex discrepancy between karyotype and MLPA.