Table 3 Allele frequencies for the GRIK2 TAA repeat length polymorphism.

Repeat number	Venezuela mean onset	Venezuela frequency (%)	England frequency (%)	US frequency (%)	“Allele number”
9			0.2		134
10	–	0.2			137
11			0.4	0.4	140
12	37.0	4.8	5.2	6.4	143
13	33.0	19.6	8.5	13.6	146
14	34.9	52.9	66.2	63.0	149
15	32.6	22.0	16.7	13.6	152
16	29.7	0.3	2.5	2.7	155
17	41.0	0.2	0.4	0.2	158
18				0.2	161

GRIK2 TAA repeat lengths were determined for 629 people (359 of whom are affected with Huntington's disease) in the Venezuelan kindreds. Allele frequency in all 629 and allelic age of onset for the 359 affected people are given. No affected people had a 10‐repeat allele. Allele number but not repeat length number was reported for the samples from England⁶ and the US.¹⁶ Assuming the allele frequencies in the three populations are comparable, the repeat numbers and allele numbers correspond as shown in the table, with the major 14‐repeat allele in Venezuela being identical to allele 149 in the studies from England and the US. The key risk allele in the previous studies is allele number 155 and it is presumed to be identical to the 16‐repeat allele. This key risk allele is 8–9‐fold more prevalent in the samples from England and the US than in those from Venezuela.