SMN protein levels in PBMCs and fibroblasts from patients and controls and effect of SMN2 copy numbers.

Mean SMN protein levels are higher in controls compared to patients. SMN protein levels in PBMCs did not differ significantly between patients with 2, 3, 4 or 5 SMN2 copies (p = 0.06). Higher SMN2 copy number is associated with higher levels of SMN protein in fibroblasts (p = 0.01). Boxplot elements represent: median (line in the middle), 1st en 3rd quartile (bottom and top of the box), highest case with 1.5 time inter-quartile range (bottom and top whisker) and outliers (dots).