Despite a lower average age of the HD donors, it is evident that a trend presents where HD patient fibroblasts exhibit higher levels of MAO-A expression and activity, although this difference did not reach statistical significance (Fig. 5a–b) (unpaired two-tailed t test; p = 0.08 for MAO-A mRNA and p = 0.06 for MAO-A activity). Here, MAOA is linked to Huntington disease.