High blood cholesterol concentration, mainly caused by high dietary cholesterol, is a potential risk factor for human health. Dairy products are important sources of human dietary cholesterol intake. Therefore, monitoring bovine milk cholesterol concentration is important for human health benefit. Genetic selection for improvement of cow milk cholesterol content requires understanding of the genetics of milk cholesterol. For this purpose, we performed analyses of additive and dominance effects of 126 potentially functional SNPs within 43 candidate genes with milk cholesterol content [expressed as mg of cholesterol in 100 g of fat (CHL_fat) or in 100 mg of milk (CHL_milk)]. The additive and dominance effects of SNPs rs380643365 in AGPAT1 (P = 0.04) and rs134357240 in SOAT1 (P = 0.035) genes associated significantly with CHL_fat. Moreover, five (rs109326954 and rs523413537 in DGAT1, rs109376747 in LDLR, rs42781651 in FAM198B and rs109967779 in ACAT2) and four (rs137347384 in RBM19, rs109376747 in LDLR, rs42016945 in PPARG and rs110862179 in SCAP) SNPs were significantly associated with CHL_milk (P < 0.05) based on additive and dominance effect analyses respectively. Rs109326954 and rs523413537 in DGAT1 explained a considerable portion of the phenotypic variance of CHL_milk (7.54 and 6.84% respectively), and might be useful in selection programs for reduced milk cholesterol content. Several significantly associated SNPs were in genes (such as ACAT2 and LDLR) involved in cholesterol metabolism in the liver or cholesterol transport, suggesting multiple mechanisms regulating milk cholesterol content. Nine and seven SNPs identified by additive or dominance effect analyses associated significantly with milk yield and fat yield respectively. Further analyses are required to better understand the consequences of these variants and their potential use in genomic selection of the studied traits.

中文翻译：

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靶向基因分型，以识别与牛乳中胆固醇含量相关的潜在功能变异

高血胆固醇浓度（主要由高饮食胆固醇引起）是人类健康的潜在危险因素。乳制品是人类饮食中胆固醇摄入的重要来源。因此，监测牛乳中胆固醇的浓度对人类健康至关重要。为提高母乳胆固醇含量而进行的遗传选择需要了解母乳胆固醇的遗传学。为此，我们对43个候选基因（含牛奶胆固醇含量[表示为100克脂肪（CHL_fat）或100毫克牛奶（CHL_milk）中的毫克胆固醇）]中的126个潜在功能性SNP的加性和优势作用进行了分析。SNP rs380643365在AGPAT1中的加性和优势效应（P  = 0.04）和SOAT1中的rs134357240（P  = 0.035）与CHL_fat显着相关的基因。此外，五（rs109326954和rs523413537 DGAT1，rs109376747在LDLR，rs42781651中FAM198B和rs109967779在ACAT2）和四（rs137347384在RBM19，rs109376747在LDLR，rs42016945中PPARG和rs110862179在SCAP）个SNPs显著与CHL_milk（相关联的P  < 0.05），分别基于加性效应和优势效应分析。Rs109326954和rs523413537 DGAT1解释了CHL_milk的很大一部分表型差异（分别为7.54和6.84％），并且对于减少牛奶中胆固醇含量的选择程序可能有用。几个显着相关的SNP位于参与肝脏胆固醇代谢或胆固醇转运的基因（例如ACAT2和LDLR）中，表明调节牛奶胆固醇含量的多种机制。通过加性或优势效应分析确定的九个和七个单核苷酸多态性分别与牛奶产量和脂肪产量显着相关。需要进一步分析以更好地理解这些变异的后果及其在研究性状的基因组选择中的潜在用途。