不良遺傳型頻率與混合樣本數對DNA遺傳檢測的經濟效益影響

黃鈺嘉 林德育 陳若菁 張秀鑾

台灣省畜產試驗所

以雜合牛及正常型的牛淋巴球黏力缺失症牛隻(BL與TL)的全血或DNA進行1:1 , 1:3, 1:4 至 1:9的混合後,再以混合的樣本進行後續的遺傳檢測工作,如DNA的限制炊螺弇P聚合玟s索反應等。結果顯示即使是 1:9的混合仍可測出雜合型(BL)的存在。但是隨著混合樣本數的增加,膠片上雜合型特有的條帶就會漸淡,在五隻樣本混合時常(1:4 )呈相的效果仍不錯。經濟效益模擬分析:假設共有壹千隻待檢測動物,依不良遺傳型的頻率變化與不同的混合樣本數對DNA遺傳檢測所需的總次數進行估算,只要混合樣本中測出有雜合型者,則需回溯重測個別原未混合的樣本。估算結果顯示:不良遺傳型的頻率在0.1%之下時,只要能正確的檢測出帶有雜合型的混合樣本,則越多的樣本混合應越有經濟效益,但是隨著不良遺傳型的頻率增加到10%,則混合樣本的效益就不存在。綜合而言,以現階段的技術而言,混合樣本之DNA遺傳檢測可應用於經濟價值較低且不良遺傳型頻率很低(反之或接近100%時)的遺傳篩選應用。

關鍵語:混合樣本、遺傳檢測。

 

INFLUENCE OF FREQUENCY OF UNDESIRED GENOTYPES AND
NUMBER OF SAMPLES MIXED ON ECONOMIC EFFICIENCY OF
DNA TEST IN GENETIC APPLICATIONS

Y. C. Huang, D. Y. Lin, J. C. Chen and H. L. Chang

Taiwan Livestock Research Institute

Samples of whole blood of different genotypes of Bovine Leukocyte Adhesion Deficiency, BL and TL(carrier and normal), were mixed from 1:1 , 1:3, 1:4 to 1:9. Mixed samples were also collected from extracted DNA with the same mixed ratio. Both restricted enzyme PCR products showed that up to 1:9 mixed sample can be detected the exist of the carrier(BL) genotype. However as the number of samples increased also decrease the blackness of the band of the image. In output analyzing, the five samples mixed, 1:4, can generate acceptable image for visual judgement. Simulation study of economic efficiency was based on frequencies of undesired genotypes of 1000 animals and numbers of samples mixed. If detects the mixed sample holding the undesired genotypes, a redo test need be performed for each unmixed sample. As the undesired genotypes bellowed 0.1%, the more samples mixed the less tests required. However, if the undesired genotypes were more than 10%, mixed samples showed only little benifit over unmixed test. Mixed DNA test could be applied in screening undesired genotypes for animals with less economic value especially when the undesired genotypes frequency was low.

Key Words: Mixed samples, Genetic test.