A missense mutation in the follicle stimulating hormone receptor (FSHR) gene shows different allele effects on litter size in Chinese Erhualian and German Landrace pigs

The follicle stimulating hormone receptor (FSHR) is a unique member of the glycoprotein hormone receptor family. Its expression is highly gonad- and cell-specific, demonstrating its importance for oogenesis and spermatogenesis. Based on published porcine FSHR gene sequence, a pair of primers was designed to amplify a 674-bp fragment of exon 10. The genetic polymorphism was detected by PCR-single strand conformation polymorphism (PCR-SSCP) analysis and a C/T substitution was revealed by direct sequencing of PCR products of putative SSCP homozygotes. This C-to-T transition led to an isoleucine 377-to-threonine substitution in the porcine FSHR protein. Bi-directional PCR amplification of specific allele (Bi-PASA) assay was developed to genotype this C/T substitution on 75 pure Chinese Erhualian (347 litter records) and 113 pure German Landrace sows (501 litter records). The general linear model (GLM) procedure of SAS analysis revealed significant associations of the marker with total piglets born in these two breeds, but showing different allele effects. In Chinese Erhualian pigs, the homozygous T/T genotype was associated with 2.12 and 1.46 piglets more in total born than the homozygous C/C and heterozygous C/T genotype (p = 0.0137). In contrast, German Landrace pigs of homozygote T/T produced 1.92 and 2.14 piglets less in total born than pigs of homozygote C/C and heterozygote C/T (p = 0.0499). This result indicates that genes could interact differently due to the genetic background in livestock species.