Phua S H, Dodds K G, Morris C A, Paterson K A, McEwan J C, Garmonsway H G, Towers N R, Crawford A M
Department of Biochemistry, University of Otago, Dunedin, New Zealand.
Anim Genet. 1999 Aug;30(4):286-95. doi: 10.1046/j.1365-2052.1999.00516.x.
Facial eczema (FE) is a hepatogenous photosensitization disease of ruminant animals, particularly in sheep which vary widely in their susceptibility to the disease. The liver damage is caused by the mycotoxin, sporidesmin. There is evidence that the toxicity of sporidesmin is due to its ability to generate 'active oxygen' species. We evaluated the catalase gene, which encodes an enzyme with antioxidant functions, as a candidate for determining the susceptibility of sheep to the disease. Two microsatellite markers, OarSHP3 and OarSHP4, which flank the sheep catalase gene, were isolated from a Yeast Artificial Chromosome (YAC) clone. These markers mapped the catalase locus by linkage to ovine chromosome 15. Eleven informative markers spaced throughout chromosome 15, inclusive of the catalase marker OarSHP4, gave no significant linkage with the disease traits when analysed in four outcross resource pedigrees. However, OarSHP3 and OarSHP4 allele frequencies showed significant differences between FE resistant and susceptible selection-lines. Comparison of sequences of catalase cDNAs from sheep of resistant and susceptible lines showed only two silent mutations. A single nucleotide polymorphisms (KP1) in exon 6 of the catalase gene also showed significant differences in allele frequencies between the selection lines. The lack of evidence for linkage in outcross pedigrees, but the significant association in the genetic lines, implies that catalase is involved in determining the susceptibility of sheep to facial eczema, and that the candidate gene's effect is probably recessive or minor.
面部湿疹（FE）是反刍动物的一种肝源性光敏性疾病，在绵羊中尤为常见，不同绵羊对该病的易感性差异很大。肝脏损伤由霉菌毒素孢霉菌素引起。有证据表明，孢霉菌素的毒性归因于其产生“活性氧”物质的能力。我们评估了编码具有抗氧化功能酶的过氧化氢酶基因，将其作为确定绵羊对该病易感性的候选基因。从酵母人工染色体（YAC）克隆中分离出位于绵羊过氧化氢酶基因两侧的两个微卫星标记OarSHP3和OarSHP4。这些标记通过与绵羊15号染色体连锁定位了过氧化氢酶基因座。在四个杂交资源系谱中分析时，遍布15号染色体的11个信息性标记（包括过氧化氢酶标记OarSHP4）与疾病性状无显著连锁关系。然而，OarSHP3和OarSHP4等位基因频率在抗FE和易感选择系之间存在显著差异。抗性和易感系绵羊过氧化氢酶cDNA序列比较仅显示两个沉默突变。过氧化氢酶基因外显子6中的一个单核苷酸多态性（KP1）在选择系之间的等位基因频率上也显示出显著差异。杂交系谱中缺乏连锁证据，但在遗传系中存在显著关联，这意味着过氧化氢酶参与了绵羊对面部湿疹易感性的决定，并且该候选基因的效应可能是隐性的或微小的。
