Ali Alsagher O A, Stear Abigail, Fairlie-Clarke Karen, Brujeni Gholamreza Nikbakht, Isa N Mahiza Md, Salisi M Shahrom Bin, Donskow-Łysoniewska Katarzyna, Groth David, Buitkamp Johannes, Stear Michael J
Animal Medicine Department, Faculty of Veterinary Medicine, South Valley University, Qena, Egypt.
Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Garscube Campus, Bearsden Road, Glasgow, Scotland, G61 1QH, UK.
Immunogenetics. 2017 Mar;69(3):157-163. doi: 10.1007/s00251-016-0962-6. Epub 2016 Dec 5.
Understanding the structure of the major histocompatibility complex, especially the number and frequency of alleles, loci and haplotypes, is crucial for efficient investigation of the way in which the MHC influences susceptibility to disease. Nematode infection is one of the most important diseases suffered by sheep, and the class II region has been repeatedly associated with differences in susceptibility and resistance to infection. Texel sheep are widely used in many different countries and are relatively resistant to infection. This study determined the number and frequency of MHC class II genes in a small flock of Texel sheep. There were 18 alleles at DRB1, 9 alleles at DQA1, 13 alleles at DQB1, 8 alleles at DQA2 and 16 alleles at DQB2. Several haplotypes had no detectable gene products at DQA1, DQB1 or DQB2, and these were defined as null alleles. Despite the large numbers of alleles, there were only 21 distinct haplotypes in the population. The relatively small number of observed haplotypes will simplify finding disease associations because common haplotypes provide more statistical power but complicate the discrimination of causative mutations from linked marker loci.
了解主要组织相容性复合体的结构,尤其是等位基因、基因座和单倍型的数量及频率,对于有效研究MHC影响疾病易感性的方式至关重要。线虫感染是绵羊所患的最重要疾病之一,II类区域一直与感染易感性和抗性的差异相关。特克塞尔羊在许多不同国家广泛使用,且相对抗感染。本研究确定了一小群特克塞尔羊中MHC II类基因的数量和频率。DRB1有18个等位基因,DQA1有9个等位基因,DQB1有13个等位基因,DQA2有8个等位基因,DQB2有16个等位基因。几种单倍型在DQA1、DQB1或DQB2处没有可检测到的基因产物,这些被定义为无效等位基因。尽管等位基因数量众多,但群体中仅有21种不同的单倍型。观察到的单倍型数量相对较少将简化疾病关联的查找,因为常见单倍型提供了更大的统计效力,但会使区分致病突变与连锁标记基因座变得复杂。