Titin-cap (TCAP) polymorphisms associated with marbling score of beef.

Marbling score (MS) is the major qualitative trait that affects carcass quality in beef cattle. In this study, we examined the association between genetic polymorphisms of the titin-cap gene (TCAP) and carcass traits in Korean native cattle (also known as Hanwoo). By direct DNA sequencing in 24 unrelated Korean cattle, we identified five sequence variants in 1.2kb of TCAP. Among them, four common polymorphic sites were selected for genotyping in the beef cattle (n=437). Pair-wise linkage analysis with four polymorphisms showed strong linkage disequilibrium (LD), and three major haplotypes (freq.>0.1) were constructed. Statistical analysis revealed that polymorphisms in intron1 (g.346G>A) and exon2 (g.592-597CTGCAG[Leu-Gln]insdel) showed significant association with marbling score (P(cor.)=0.003 and 0.02, respectively). One haplotype, ht2[C-G-G-del], also showed significant association with MS (P(cor.)=0.0004). Our findings suggest that polymorphisms in TCAP might be among the important genetic factors involved in carcass quality in beef cattle.