猪2、7和8号染色体上影响血常规指标的数量性状基因座(QTL)检测

Detection of Quantitative Trait Loci Affecting Haematological Traits on Swine Chromosomes 2,7 and 8

以3个品种(长白猪、大白猪、松辽黑猪)16个公猪家系共计368头仔猪组成资源群体,在猪2、7和8号染色体上共选取35个微卫星标记,采用基于线性混合模型的方差组分分析方法,对影响与猪白细胞、红细胞和血小板相关的共计18项血常规指标的数量性状基因座(quantitative trait loci,QTL)进行了检测.通过似然比检验,并以自由度为2的卡方分布作为检验统计量的分布,共发现22个在P<5%水平下显著的QTL,其中在2号染色体上有9个,分别影响白细胞总数、中性粒细胞数、平均红细胞体积、血红蛋白含量、平均红细胞血红蛋白浓度、血小板总数、平均血小板体积、血小板分布宽度和血小板压积,在7号染色体有7个,分别影响白细胞总数、中性粒细胞数、平均红细胞血红蛋白浓度、血红蛋白含量、血小板总数、平均红细胞体积和红细胞分布宽度变异,在8号染色体上有6个,分别影响中性粒细胞百分比、淋巴细胞百分比、平均红细胞血红蛋白浓度、血小板总数、血小板压积和平均红细胞体积.为尽可能地避免由于多重检验所造成的假阳性率的升高,我们采用了控制假检出率(false discovery rate,FDR)的方法来对这22个QTL进行进一步检验,发现有14个达到FDR<5%显著水平,其中又有9个达到FDR<1%显著水平.

Haematological traits, which consist of mainly three components： leukocyte traits, erythrocyte traits and platelet traits, play extremely important role in disease resistance. But knowledge of the genetic background controlling variability of these immune traits is very limited, especially in swine. 18 haematological traits including white blood cell count （WBC）, neutrophilic granulocyte count （GRAN） and percentage （GR%）, lymphocyte count （LYMF） and percentage （LY%）, monocytes count （MONO） and percentage （MO%）, red blood cell （RBC）, hemoglobin （HGB）, hematocrit （HCT）, mean corpuscular volume （MCV）, mean corpuscular hemoglobin （MCH）, mean corpuscular hemoglobin concemtration （MCHC）, red blood cell volume distribution width （RDW）, blood platelet counts （PLT）, mean platelet volume （MPV）, platelet distribution width （PDW）, and plateletocrit （PCT） were measured in a pig resource population consisting of 368 piglets of three breeds （Landrace, Large White and Songliao Black Pig） distributed in 16 boar families, after inoculation with the swine fever vaccine at 21 days of old. A partial genome scan for mapping quantitative trait loci （QTL） for these traits was performed using 35 microsatellite markers on chromosomes 2, 7, and 8. Using variance component analysis based on a linear mixed model and likelihood ratio test based on a chi-square distribution with 2 degrees of freedom, 22 significant QTL （P 〈 5%） were identified： 9 on chromosome 2 affecting WBC, GRAN, MCV, HGB, MCHC, PLT, MPV, PDW and PCT, respectively; 7 on chromosome 7 affecting WBC, GRAN, MCHC, HGB, PLT, MCV and RDW, respectively; 6 on chromosome 8 affecting GR%, LY%, MCHC, PLT, PCT and MCV, respectively. In order to avoid the increase of false positive rate caused by multiple tests, the FDR （false discovery rate） control approach was adopted to further test these 22 QTL. The results indicated that 14 of them were significant at FDR 〈 5% level, of which 9 were significant at FDR〈1% level.