Fig. 1

Southern blot of genomic DNA from isogenic pairs of stem cell clones derived from FSHD-affected individuals with mosaicism. Genomic DNA from hiPS cell clones was digested with EcoRI and HinDIII restriction endonucleases and separated by size on an agarose gel using pulsed field gel electrophoresis. A Southern blot of this gel was probed with P³²-labeled p13E-11 fragments and exposed on autoradiography film. The bands shown in each lane correspond to maternal and paternal D4Z4 arrays on chromosomes 4 and 10 (4 arrays/lane). Lanes 2 and 3 show D4Z4 array sizes present in hiPSC clones derived from mosaic1 with a 107 kb chromosome 4 array in the “long” clone and the same array reduced to ~19 kb size in the “short” clone (indicated by arrows). Lanes 3 and 4 show D4Z4 array sizes from hiPSC clones derived from mosaic2 with a 220 kb chromosome 4 array in the “long” clone and the same array reduced to ~15 kb in the “short” clone from the same person (indicated by arrows). DNA size markers are shown in lane 1. Chromosome 4-type and 10-type arrays were distinguished by further digestion with XapI to remove chromosome 4-type arrays or BlnI to remove chromosome 10-type arrays. Additional blots were probed with “A” and “B” probes recognizing the distal end of the arrays to confirm that the chromosome 4 arrays varying in size are permissive A-type arrays generally known to produce FSHD when <11 units long