|Chitko Mckown, Carol|
Submitted to: Plant and Animal Genome Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: January 10, 2004
Publication Date: January 10, 2004
Citation: LAEGREID, W.W., CLAWSON, M.L., HEATON, M.P., KEEN, J.E., CHITKO MCKOWN, C.G., FOX, J.M., SMITH, T.P., SNELLING, W.M., KEELE, J.W. GENETIC RISK FACTORS FOR FAILURE OF PASSIVE TRANSFER IN THE BOVINE NEONATAL FC RECEPTOR. PLANT AND ANIMAL GENOME CONFERENCE PROCEEDINGS. ABSTRACT NO. P642. Technical Abstract: The neonatal Fc receptor, FcRn is a heterodimer composed of two non-covalently associated polypeptides, Beta2-microglobulin and an MHC Class I alpha-chain homolog. These polypeptides are encoded by the B2M and FCGRT genes, respectively. FcRn participates in several processes including modulating IgG concentration in mammary secretions, uptake of IgG from the intestinal lumen of neonates and maintenance of circulating levels of IgG. The involvement of FcRn in passive transfer of immunoglobulin and the relatively high reported heritability of failure of passive transfer (FPT) in calves, lead us to hypothesize that alleles of B2M and FCGRT affect FPT in calves. Thirteen B2M single nucleotide polymorphisms (SNPs) defining eight haplotypes were identified and verified by segregation. Five SNPs defining five FCGRT haplotypes were also identified and verified by segregation. Using a case-control design, calves homozygous for B2M haplotype 2 had an increased risk of FPT (OR = 10.60, CI95% 2.1 - 54.2, p = 0.005). Dams with FCGRT haplotype 3 had a significantly greater risk of FPT in their calves (odds ratio [OR] = 3.8, CI95% 1.1 - 13.2, p = 0.035). Calves with either B2M or FCGRT risk factor alleles, or both, accounted for 54% of all FPT cases in this study while only 16% of control calves had one or both risk factors. These results indicate that alleles of B2M and FCGRT represent significant risk factors for FPT, a condition that results in increased morbidity and mortality in young calves.