Mass spectrograms of Prnp genotypes for SNPs at codons 210 and 211 in U.S. cattle. Spectral peaks represent singly-charged ions whose mass-to-charge ratio (m/z) was compared with calibrants for mass determination. Panels A, B, and C: Representative mass spectrograms showing the three haplotype combinations observed in U.S. cattle in their order of prevalence: cE211/cE211, cE211/tE211, and tE211/tE211. The "antisense nE211" designation refers to a peak generated by either a cE211 or a tE211 allele because the genotype for this analyte is ambiguous in the antisense direction. Although conservative hME assay designs include 40 Dalton spacing between analytes, only 15 Dalton spacing was possible in this assay design. Nevertheless, the typical instrument resolution of approximately 4 Daltons is sufficient to resolve the analytes. Panel D: Mass spectrogram of the diplotype reconstituted from cloned cDNA of the 2006 Alabama BSE case.