title: Associations between variants of the HAL gene and milk production traits in Chinese Holstein cows.
abstract: BACKGROUND
  The histidine ammonia-lyse gene (HAL) encodes the histidine ammonia-lyase, which catalyzes the first reaction of histidine catabolism. In our previous genome-wide association study in Chinese Holstein cows to identify genetic variants affecting milk production traits, a SNP (rs41647754) located 357 bp upstream of HAL, was found to be significantly associated with milk yield and milk protein yield. In addition, the HAL gene resides within the reported QTLs for milk production traits. The aims of this study were to identify genetic variants in HAL and to test the association between these variants and milk production traits.
  
  
  RESULTS
  Fifteen SNPs were identified within the regions under study of the HAL gene, including three coding mutations, seven intronic mutations, one promoter region mutation, and four 3'UTR mutations. Nine of these identified SNPs were chosen for subsequent genotyping and association analyses. Our results showed that five SNP markers (ss974768522, ss974768525, ss974768531, ss974768533 and ss974768534) were significantly associated with one or more milk production traits. Haplotype analysis showed that two haplotype blocks were significantly associated with milk yield and milk protein yield, providing additional support for the association between HAL variants and milk production traits in dairy cows (P < 0.05).
  
  
  CONCLUSIONS
  Our study shows evidence of significant associations between SNPs within the HAL gene and milk production traits in Chinese Holstein cows, indicating the potential role of HAL variants in these traits. These identified SNPs may serve as genetic markers used in genomic selection schemes to accelerate the genetic gains of milk production traits in dairy cattle.
authors.affiliation: Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China. wanghaiffei@126.com.
authors.forename: Haifei
authors.initials: H
authors.lastname: Wang
authors.affiliation: Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China. jiangli198374@163.com.
authors.forename: Li
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China. wwwwangwen@126.com.
authors.forename: Wenwen
authors.initials: W
authors.lastname: Wang
authors.affiliation: Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China. zhang62733697@163.com.
authors.forename: Shengli
authors.initials: S
authors.lastname: Zhang
authors.affiliation: College of Animal Science and Technology, Anhui Agricultural University, Hefei, 230036, China. yinzongjun@ahau.edu.cn.
authors.forename: Zongjun
authors.initials: Z
authors.lastname: Yin
authors.affiliation: Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China. qzhang@cau.edu.cn.
authors.forename: Qin
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China. liujf@cau.edu.cn.
authors.forename: Jian-Feng
authors.initials: JF
authors.lastname: Liu
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002417:Cattle / Q000235:genetics*; D002681:China; D005260:Female; D015870:Gene Expression; D005787:Gene Frequency; D056726:Genetic Association Studies; D006239:Haplotypes; D006638:Histidine Ammonia-Lyase / Q000235:genetics* / Q000378:metabolism; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism; D015810:Linkage Disequilibrium; D008892:Milk / Q000378:metabolism*; D020641:Polymorphism, Single Nucleotide
chemical_list: D020413:3' Untranslated Regions; D051741:Kruppel-Like Transcription Factors; D006638:Histidine Ammonia-Lyase