Table 3. Comparison of PRNP codon 129 genotype frequencies and incubation periods in growth hormone– and dura mater–associated cases of iatrogenic CJD*.

Category	MM	VV	Homozygotes	Heterozygotes
Population
Healthy Caucasian, %†	40	10	50	50
European, with sporadic CJD, %	67	17	84	16
Healthy Japanese, %	92	0	92	8
Japanese, with sporadic CJD, (%)	97	1	98	2
Infection source
Growth hormone
France (111)
Genotype frequency, %	54	15	69	31
Incubation period, y	12	9	11	17
United Kingdom (28)
Genotype frequency, %	4	50	54	46
Incubation period, y	21	18	20	23
United States (11)
Genotype frequency, %	55	18	73	27
Incubation period, y	21	18	20	23
Combined total (150)
Genotype frequency, %	45	22	67	33
Incubation period, y	13	12	13	17
Dura mater
Japan (54)‡
Genotype frequency, %	96	0	96	4
Incubation period, y	16	NA	16	13
Countries other than Japan (54)§
Genotype frequency, %	65	15	80	20
Incubation period, y	12	12	12	16
Combined total (108)
Genotype frequency, %	81	7	88	12
Incubation period, y	14	12	14	16

*CJD, Creutzfeldt-Jakob disease; M, methionine; V, valine; NA, not applicable. All values are rounded to the nearest whole number.
†Based on several large-scale population studies (5–9).
‡Personal communication from M. Yamama, Department of Neurology, Kanazawa University Hospital, Kanazawa, Japan.
§Cases from France (11), Spain (11), Germany (10), Italy (8), the Netherlands (5), and 1 or 2 cases from each of 6 other countries with Caucasian populations.