The porcine MUC20 gene: molecular characterization and its association with susceptibility to enterotoxigenic Escherichia coli F4ab/ac

Enterotoxigenic Eschoerchia coli (ETEC) F4 is a major cause of diarrhea in neonatal and young pigs. The locus encoding intestinal receptor for ETEC F4ab/ac has been mapped to pig chromosome (SSC) 13q41. We previously assigned mucin 20 (MUC20) to SSC13q41 and considered it a candidate for the ETEC F4ab/ac receptor. In this study, the full-length mRNA sequence of the porcine MUC20 gene was determined, revealing two MUC20 alternative transcripts differing in an 18-bp deletion in the open reading frame (ORF). The longer isoform is 1,927-bp long and contains a 1,572-bp ORF encoding a protein of 523 amino acids. RT–PCR analysis showed that MUC20 mRNA was expressed most highly in the kidney, prostate, epididymis and bladder. Seven single nucleotide polymorphisms in MUC20 were identified in founder animals of a White Duroc × Erhualian cross, and the entire cross population (n = 842) was genotyped for two MUC20 polymorphisms: g.191C>T in intron 5 and c.1600C>T in exon 6. The transmission disequilibrium test (TDT) results revealed that both polymorphisms were significantly associated with in vitro ETEC F4ab/ac adhesion phenotypes in the intercross population, and the most significant association was found between g.191C>T and F4ac adhesion phenotype (P = 1.02 × 10−9).