Mosaic unbalanced structural abnormalities confirmed using FISH on buccal mucosal cells.

Three rare mosaic unbalanced structural rearrangements found in routine peripheral blood analysis were confirmed in buccal mucosal cells using interphase FISH. Case 1 had a de novo mosaic triplication for 13q22q33 found in 22.5 % lymphocytes. D13S585 probe that maps to 13q32q33 confirmed the mosaicism in 41 % of buccal mucosal cells. Case 2 had additional material on a 3q derived from 14q31qter in 83 % of lymphocytes. The 14q-subtelomeric probe was used on buccal smear cells: 86 % had three signals and 14 % had two signals. Case 3 was a mosaic de novo add(5) in 32 % lymphocytes. The additional material was from 3p26pter. The 3p-subtelomere probe confirmed the mosaicism in 40 % buccal epithelial cells. This study shows the applicability of interphase FISH to confirm mosaic unbalanced rearrangements in a second tissue such as buccal mucosal cells.