Figure 2. Somatic mosaicism increases in blood and post-mortem cortex over time.

Comparison of mosaicism in cortical tissue from Huntington disease (HD) carrier fetuses at 13 weeks (green), blood samples over time (gold, orange, and red for t1, t2, and t3, respectively) and adult post-mortem cortices (blue). We ascertained the ‘% mutant alleles’ (as in Figure 1C) from the peak heights from PCR profiles obtained on GeneMapper. Three reference CAG lengths (41, 43, or 45 CAG) were chosen from our cohort to illustrate the evolution of instability, and each graph represents one individual patient (from top to bottom): for the fetal samples, patients 2, 4, and 5 (Table 1); for the blood samples, the repeated measures from patients 4, 19, and 34 (Table 2); for the post-mortem samples, patients 2, 5, 10 (Table 3).