<p>Populations with ≥100 examined HD patients are shown; <i>n</i> number of investigated HD patients.</p><p>AAO, age at onset, CAGexp, expanded CAG repeat number in huntingtin, SD standard deviation, V major allele valine at amino acid position 471 (V471), A rare allele alanine at amino acid position 471 (A471).</p>a<p>t test: Comparing the mean AAO of the VV and VA genotypes in the different populations, only Italian patients with genotype VV differ significantly from patients with heterozygous VA genotype (P = 0.0348).</p>b<p>t-test: Italian patients show the oldest mean AAO, which is significantly older than the mean AAO of patients from the other presented European countries together (Italy vs other countries: P<0.0001), but not significantly different from the mean AAO of patients from Denmark (P = 0.4728) and France (P = 0.2050).</p
