Johansson Moller M, Chaudhary R, Hellmén E, Höyheim B, Chowdhary B, Andersson L
Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Mamm Genome. 1996 Nov;7(11):822-30. doi: 10.1007/s003359900244.
Comparative mapping data suggested that the dominant white coat color in pigs may be due to a mutation in KIT which encodes the mast/stem cell growth factor receptor. We report here that dominant white pigs lack melanocytes in the skin, as would be anticipated for a KIT mutation. We found a complete association between the dominant white mutation and a duplication of the KIT gene, or part of it, in samples of unrelated pigs representing six different breeds. The duplication was revealed by single strand conformation polymorphism (SSCP) analysis and subsequent sequence analysis showing that white pigs transmitted two nonallelic KIT sequences. Quantitative Southern blot and quantitative PCR analysis, as well as fluorescence in situ hybridization (FISH) analysis, confirmed the presence of a gene duplication in white pigs. FISH analyses showed that KIT and the very closely linked gene encoding the platelet-derived growth factor receptor (PDGFRA) are both located on the short arm of Chromosome (Chr) 8 at band 8p12. The result revealed an extremely low rate of recombination in the centromeric region of this chromosome, since the closely linked (0.5 cM) serum albumin (ALB) locus has previously been in situ mapped to the long arm (8q12). Pig Chr 8 shares extensive conserved synteny with human Chr 4, but the gene order is rearranged.
比较图谱数据表明，猪的显性白色被毛颜色可能是由于编码肥大/干细胞生长因子受体的KIT基因发生了突变。我们在此报告，显性白色猪的皮肤中缺乏黑素细胞，这与KIT基因突变的预期情况相符。在代表六个不同品种的无关猪样本中，我们发现显性白色突变与KIT基因或其部分基因的重复完全相关。通过单链构象多态性（SSCP）分析及随后的序列分析揭示了这种重复，结果表明白色猪传递了两个非等位的KIT序列。定量Southern印迹和定量PCR分析以及荧光原位杂交（FISH）分析，证实了白色猪中存在基因重复。FISH分析表明，KIT基因以及与血小板衍生生长因子受体（PDGFRA）编码基因紧密连锁的基因均位于8号染色体（Chr）短臂的8p12带。该结果揭示了该染色体着丝粒区域的重组率极低，因为之前已将紧密连锁（0.5 cM）的血清白蛋白（ALB）基因座定位到长臂（8q12）。猪的8号染色体与人类的4号染色体具有广泛的保守同线性，但基因顺序发生了重排。
