Detection of dystrophin exon 45 deletion in DMD-BMT1 and his mother by FISH analysis. (a) Unaffected female. Chromosomes are counterstained in blue by 4′,6-diamidine-2-phenylindole dihydrochloride (DAPI) and both X chromosomes have red hybridizations signals using a dystrophin exon 45–specific probe. (b) DMD-BMT1’s mother’s chromosome spreads. Only one X chromosome hybridized with the dystrophin exon 45-specific probe, thus confirming her DMD carrier status for dystrophin exon 45 deletion. (c) DMD-BMT1 fibroblast nuclei hybridized with an X-centromeric probe (green) and a dystrophin exon 45 probe (red), which failed to hybridize. (d and e) Detection of donor-derived nuclei in MSC cultures of DMD-BMT1. (d) By immunofluorescence, more than 95% of cultured MSCs from DMD-BMT1 are positive for CD105 (green). (e) FISH analysis using a dystrophin exon 45 cosmid probe (red) shows presence of donor-derived MSCs. (f and g) Simultaneous hybridization of DMD-BMT1 MSC nuclei with an X-centromeric DNA probe (green) and dystrophin exon 45 probe (red) by FISH. Donor nuclei in DMD-BMT1 MSCs are diploid. (h and i) Nuclei from an unaffected female hybridized by FISH with the X-centromeric and dystrophin exon 45 FISH probes. Two green and red hybridization signals are expected in each nucleus. Nuclei are counterstained in blue by DAPI.