Haplotypic diversity of porcine LEP and LEPR genes involved in growth and fatness regulation.

The analysis of structural genetic variability in candidate genes can make it possible to analyse the selection footprint and deepen the understanding of the genetic basis of complex traits. The leptin (LEP) and its receptor (LEPR) porcine genes are involved in food intake and energy homeostasis, and polymorphisms associated to growth and fatness traits have been detected in both genes. The main objective of this study was to explore the genetic variability of the most polymorphic regions of both genes in a variety of pig populations and wild boars from diverse European and Asian origins. In total, 54 animals were included in the analyses, with a remarkable sampling of Spanish wild boars and Iberian pigs. The sequencing allowed the identification of 69 and 26 polymorphisms in LEP and LEPR genes, respectively. Neighbour-joining trees built for the 69 haplotypes identified in the LEP and the 24 haplotypes detected in the LEPR showed the known genetic divergence between European and Asian pig breeds. A high variability of the LEP was detected in the different analysed populations providing new data for the existence of two domestication centres in Asia. In comparison to the LEP gene, the LEPR showed a lower variability, especially in the Iberian breed that showed no variability. Moreover, results of the Hudson-Kreitman-Aguadé neutrality test support a possible selection event of the LEPR gene region in this breed, potentially related with its leptin resistance pattern and good adaptation to a traditional extensive production system with strong seasonal changes of feeding resources.