Low-density lipoprotein receptor-related protein 2 gene is associated with egg-quality traits in dwarf layers.

Some members of the low-density lipoprotein receptor (LDLR) family play important roles in the regulation of lipoprotein metabolism and egg quality traits. Low-density lipoprotein receptor-related protein 2 (LRP2) gene belongs to the LDLR super family, and widely expresses in many tissues. This work identified and genotyped 1 single-nucleotide polymorphism (SNP), T14347C, at 3'-UTR of the LRP2 using matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS), and analyzed the effects of the SNP (T14347C) on egg-quality traits in 544 dwarf hens from 44 sire families. Frequencies of this SNP in the studied population did not agree with the Hardy-Weinberg equilibrium (P < 0.0001). Egg weight, albumen weight, albumen height, and albumen ratio of the TT genotype were significantly higher than those of the CC genotype (P < 0.05), whereas eggshell ratio of the TT genotype was significantly lower than that of the CC genotype (P < 0.05). The relative expression level of the LRP2 gene in the magnum was determined by real-time quantitative PCR. The gene expression of genotype CC individuals was significantly higher than that of TT and CT birds (P < 0.05). By combining both genetic effects and expression analyses results, we propose that the LRP2 gene is a good candidate gene, exhibiting a key role in albumen formation processes.