A single nucleotide polymorphism in the parathyroid hormone gene and effects on eggshell quality in chickens.

Parathyroid hormone (PTH), released by the parathyroid gland of animals, plays an important role in regulating the metabolism of calcium and phosphate. As a candidate gene for eggshell quality traits, the SNP was screened and its genetic effects on eggshell qualities and levels of serum calcium, phosphate, and PTH were analyzed in this study. Three hundred Houdan hens, an indigenous breed of chicken in France, were used for genotyping and data recording. Of the 3 sets of primers used to amplify the exons, exon 3 was polymorphic and 3 genotypes were identified. Sequencing revealed a nucleotide transition, A2205G (GenBank accession no. NC_006092), which was a synonymous mutation and caused a codon for lysine to change from AAA to AAG. Eggshell percentage and breaking strength for genotypes GG and AG were greater (P<0.05) than for AA, respectively; the total serum calcium for genotype GG was higher than for genotypes AA and AG by 11.8 and 10.1%, respectively; the serum phosphate for genotype GG was greater than genotype AA and AG by 16.7 and 12%, respectively. All genotypes shared the same calcium:phosphate ratio. For serum PTH, genotype GG was approximately 30% higher than genotype AA. Therefore, the SNP A2205G in PTH affected the eggshell percentage and breaking strength, and it may be associated with the variation of serum calcium and PTH level, indicating that the SNP in PTH has the potential for utilization in a MAS program for eggshell quality in chicken.