美国国家人类基因组研究所16日说，一种特殊基因可能导致某些狗类身材相对矮小。这一发现可能会为人类侏儒症的研究提供新线索。
研究人员说，大多数狗类仅有一个生长相关基因，但近20种矮小狗类还有另外一个被称为“成纤维细胞生长因子4”的逆基因。
这种逆基因实际上是一种狼的基因。狗通过进化逐渐从狼类分离出来，狼的基因在进化完成之后又重新“嫁接”到狗的基因群中。
研究员海迪·帕克认为这种基因可能是在胎儿发育阶段对生长机制产生影响，抑制腿部骨骼生长，使骨骼弯曲。这种影响只作用于腿部。
帕克说：“我们感到惊讶，一个小小的‘逆基因’能在进化过程中对（狗的）物理特性产生如此巨大影响。”
她认为，研究人员可以开始研究成纤维细胞生长因子4是否与人类侏儒症中的软骨发育欠全症状有关。软骨发育欠全患者数量占所有侏儒病例的三分之一。（生物谷Bioon.com）
生物谷推荐原始出处：
Science 6 March 2009: DOI: 10.1126/science.1165448
Molecular and Evolutionary History of Melanism in North American Gray Wolves
Tovi M. Anderson,1 Bridgett M. vonHoldt,2 Sophie I. Candille,1 Marco Musiani,3 Claudia Greco,4 Daniel R. Stahler,2,5 Douglas W. Smith,5 Badri Padhukasahasram,6 Ettore Randi,4 Jennifer A. Leonard,7 Carlos D. Bustamante,6 Elaine A. Ostrander,8 Hua Tang,1 Robert K. Wayne,2 Gregory S. Barsh1*
Morphological diversity within closely related species is an essential aspect of evolution and adaptation. Mutations in the Melanocortin 1 receptor (Mc1r) gene contribute to pigmentary diversity in natural populations of fish, birds, and many mammals. However, melanism in the gray wolf, Canis lupus, is caused by a different melanocortin pathway component, the K locus, that encodes a beta-defensin protein that acts as an alternative ligand for Mc1r. We show that the melanistic K locus mutation in North American wolves derives from past hybridization with domestic dogs, has risen to high frequency in forested habitats, and exhibits a molecular signature of positive selection. The same mutation also causes melanism in the coyote, Canis latrans, and in Italian gray wolves, and hence our results demonstrate how traits selected in domesticated species can influence the morphological diversity of their wild relatives.
1 Departments of Genetics and Pediatrics, Stanford University, Stanford, CA 94305, USA.
2 Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 91302, USA.
3 Faculty of Environmental Design, University of Calgary, Calgary, AB T2N 1N4, Canada.
4 Istituto Nazionale per la Fauna Selvatica, 40064 Ozzano Emilia (BO), Italy.
5 Yellowstone Center for Resources, National Park Service, Yellowstone National Park, WY 82190, USA.
6 Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY 14853, USA.
7 Department of Evolutionary Biology, Uppsala University, 75236 Uppsala, Sweden.
8 National Human Genome Research Institute, Bethesda, MD 20892, USA.
