Fig. 1

The distribution of X chromosome inactivation (XCI) ratios in 18 patients with Klinefelter syndrome. Inactivation ratios of the shorter (carrying less repeat number) and longer alleles are shown. Skewed XCI (ratios of ≥ 80%:20%, or ≤ 20%:80%) was observed in two of the 18 patients (gray and black bars). Of these, one exhibited extremely skewed XCI (ratios of ≥ 90%:10%, or ≤ 10%:90%) (the black bar)