A-F Structure and FISH results of the mosaic inv dup(10) from case 2. 3A: FISH with WCP10 probe (green) with the (arrowed) inv dup(10) showing that the extra material is of chromosome 10 origin. Note the mid portion of the short-arm where the telomere to telomere join is located is poorly hybridized by the WCP10, possibly due to the presence of repetitive sub-telomeric sequences (competitively excluded in the WCP hybridization). 3B: FISH for the sub-telomere probe on the apparently normal cell line shows a (arrowed) sub-telomere 10p deletion (clone GS-306F7 shown in red). The intact 10q sub-telomere probe (clone GS-137E24 in green) is also demonstrated on both chromosomes. 3C: FISH for the sub-telomere probe 10p (clone GS-306F7 in green) showing a interstitial duplication (arrowed) of the 10p sub-telomere probe in the inv dup(10). The normal chromosome 10 (lower) exhibits normal probe signals at each p/q subtelomere. 3D: the pantelomeric probe (green) on the apparently normal cell line shows that TTAGGG repeats are found on the novel 10pter of the chromosome, which has a missing subtelomere 10p locus, i.e. a positive pantelomeric probe signal is present on both (open arrows) the normal chromosome 10 and the 10p with the cryptic subtelomere deletion. 3E: the pantelomeric probe (Oncor) on the inv dup(10) cell line shows that TTAGGG repeats are found on the new 10pter of the (open arrow) inv dup(10) chromosome. In this cell line the normal 10 also had a positive 10p signal for TTAGGG (not shown). 3F: FISH on an abnormal metaphase with GATA3 (shown in green and mapping to 10p14) and for NEBL (shown in red and mapping to 10p12.3) shows an inv dup pattern (arrowed), confirming the inv dup(10) structure.