Polymorphisms of the prion protein gene (PRNP) in a Korean population

Human prion protein gene (PRNP) has been considered to be involved in the susceptibility of humans to prion diseases. Polymorphisms of methionine (Met)/ valine (Val) at codon 129 and of glutamic acid (Glu)/ lysine (Lys) at codon 219 are thought to play an important role in susceptibility to sporadic, iatrogenic and variant Creutzfeldt-Jakob disease (CJD). Although the genotype distribution of polymorphisms in PRNP open reading frame (ORF) has been reported in many European populations, among Asian groups, it has been reported only in the Japanese population. We examined the PRNP polymorphisms in 529 healthy Koreans. We observed that genotype frequencies at codon 129 was 94.33% Met/Met, 5.48% Met/Val, and 0.19% Val/Val with an allele frequency of 0.971:0.029 Met:Val, and that genotype frequencies at codon 219 was 92.06% Glu/ Glu, 7.94% Glu/Lys, and 0% Lys/Lys with an allele frequency of 0.96:0.04 Glu:Lys. The frequencies of the Glu/Glu genotype (χ² = 10.075, P = 0.0015) and of the Glu allele (χ² = 9.486, P = 0.0021) at codon 219 were significantly higher in the Korean population than the Japanese population. In addition, the genotype frequency of heterozygotes (12.7%) at codons 129 or/and 219 was significantly lower in Koreans than in people from Great Britain (χ² = 89.52, P < 0.0001). The deletion rate of one octarepeat (R2 deletion) was 0.38%, with 99.62% undeleted homozygotes and 0% deleted homozygote. To our knowledge, the R2 octarepeat deletion has never been found in people from countries other than Korea. The data of PRNP polymorphism at codon 219 suggest that Koreans may be more sensitive to sporadic CJD than the Japanese population.