Association of bovine neonatal Fc receptor alpha-chain gene (FCGRT) haplotypes with serum IgG concentration in newborn calves.

This report describes allelic variation in FCGRT (which encodes the alpha-chain of FcRn) and its association with variation of IgG concentration in neonatal calves. Five SNPs were identified by sequencing 1305 bp of FCGRT genomic DNA from a multi-breed panel of 96 cattle and 27 founders of a reference population. These SNPs defined five FCGRT haplotypes that were verified by segregation and used to test association of FCGRT with neonatal IgG concentration in a case-control study. This study established that dams with FCGRT haplotype 3 had a significantly greater risk of failure of passive transfer in their calves (odds ratio [OR] = 3.80, CI95% 1.10-13.18, p = 0.035). Calves with FCGRT haplotype 2 were less likely to have high levels of passively acquired immunoglobulin (OR = 0.18, CI95% 0.05-0.68, p = 0.011). These results indicate that the bovine FCGRT haplotype markers are in linkage disequilibrium with genetic risk factors affecting passive transfer of IgG in beef cattle, an important determinant of neonatal calf morbidity and mortality.