Results of FISH analysis on embryonic nuclei with probes for the detection of the intact chromosome 22 and the ring/deleted 22 chromosome during PGD. A. First round FISH result with the Di George dual band probe set (22q11.2 orange/22q13.3 green).on a single blastomere showing loss of ring chromosome 22 detected by the orange probe. B. Normal FISH signals for chromosome 22 with the Di George dual band probe set (22q11.2 orange/22q13.3 green)., the embryo could have two intact chromosomes 22 or be a carrier. C. Second round FISH result with probes Cep14/22 (red) and 14qtel (green) on the same cell as in B, shows a balanced carrier of the ring and deleted 22.