Table 11. Structure of the OPRI region in a normal case and in the four 8-OPRI families.

Family	OPRI region	Codon 129 in the PRNP gene
Wild-type	R1-R2-R2-R3-R4	M or V
Che	R1-R2-R2-R3-R2-R2-R2-R2-R2-R2-R2-R2a-R4	V
M-E	R1-R2-R2-R3-R2-R2-R2-R2a-R2-R2-R2-R3-R4	M
A	R1-R2-R2-R3g-R3-R2-R2-R2-R2-R2-R2-R3-R4	V
Swedish	R1-R2-R2-R3g-R2-R2-R2-R3g-R3g-R2-R2-R3-R4	M

R1 encodes a nonapeptide, R2-R4 encode octapetides of similar amino acid sequence and structure. Additional repeats are in bold, R2a and R3g case are variants of R2 and R3 with a silent amino acid substitution in each.^7-10