Table 2.

Example genetic markers for infectious disease in sheep: Classical scrapie.

Species	Trait(s)	Gene	Haplotype & Variant	Effect Size	Mode of Inheritance	Breeds	Management	Locale	Potential Correlated Responses to Selection Examined
Sheep	[Common Reference Haplotype]	PRNP	ARQ haplotype Contains: A136 R154 Q171	[Common Reference Haplotype]	[Common Reference Haplotype]	Many	Many	Many	[Common Reference Haplotype]
Sheep	Probability of infection	PRNP	ARR haplotype Contains: R171	Strong resistance [115,116,117]	Dominant, except to VRQ haplotype	Many	Many	Many	Many
Sheep	Probability of infection	PRNP	VRQ haplotype Contains: V136	Strong susceptibility Often 10-fold increased risk [115,116,117]	Largely Dominant	Many	Many	Many	Many
Sheep	Probability of infection	PRNP	AHQ haplotype Contains: H154	3–7 fold risk reduction [115,116,117,122]	Partial Dominant, except to ARR or VRQ	Many	Many	Many	Many