(A) Position of GGTLA within the block structure of the LCR22s. Each of the LCR22s is ordered with respect to the centromere of chromosome 22q11.2. The GGTLA (green) gene is shown in its proper transcription orientation. The functional GGTLA locus is in LCR22-7. (B) Recombination events for GGTLA in LCR22-7 to form products in LCR22-5 and LCR20. The different recombination events in the different Alu elements shaping LCR22-5 (19661038-19665200, top; 19692592-19699596) and LCR20 (chr 20:23944266-23949403) are shown. Examination of the GGTLA intron 1 in LCR22-7 revealed duplicated copies on LCR22-8 (unrearranged), LCR22-5, and LCR20. We found rearrangements in LCR22-5 and LCR20. For LCR22-5, a single breakpoint within Alu D5 was responsible for creating the two reciprocal copies, one in the proximal end of LCR22-5 and one at the distal end of LCR22-5. Both form the borders of the LCR22. A different breakpoint, in Alu D4, was responsible for shaping the border of LCR20.
