In the present series, cleavage-stage embryo biopsy was carried
out. There seems to be evidence supporting a high mosaicism rate
in cleavage-stage embryos, and this may be one reason why PGS
seems to provide no statistically significant improvement in
outcome during clinical use [22,23]. Blastocyst biopsy is now under
investigation as a possible testing approach for use in PGS [24]. It
remains to be seen whether blastocyst biopsy is able to improve
PGD outcomes among chromosomal translocation carriers