Telomere length analysis of DC CD34⁺ cells. (A) Quantitative FISH analysis of telomere length distribution and mean or median telomere length was measured in 15 individual metaphases (or 2750 individual telomeres) for day-4 cultured CD34⁺ cells from a control mPB sample (B20337, 39 years old), a second-generation AD DC patient (UPN 6), and 2 third-generation patients (UPNs 7 and 9). (B) Representative Q-FISH metaphase spreads (and inset enlarged chromosomes) for day-4 CD34⁺ cells from a control mPB sample showing detectable telomere spots for each chromosome end and from a DC sample, showing detectable signal-free ends indicated by the white arrows.