Association analysis between novel variants in LEPR gene and litter size in Mongolia and ujimqin sheep breeds

Prolificacy is an important trait of livestock, especially for species with multiple births, such as sheep. The leptin receptor (LEPR) is considered as a major candidate gene that affects the reproductive traits of sheep. The known R62H mutation in the LEPR gene is associated with the hyperprolific phenotype of Davisdale sheep. However, studies identifying novel variations and seeking breed-specific markers associated with litter size in other sheep breeds are rare. In this study, we sequenced all coding regions of the LEPR gene of Mongolia sheep, and nine novel variants of the LEPR gene were detected by direct sequencing. Among them, the synonymous c.240C > T and c.279C > T mutations were significantly associated with the litter sizes of Mongolia ewes (P < 0.05 and P < 0.01, respectively) and Ujimqin ewes (P < 0.05 and P < 0.01, respectively). The silent c.240C > T and c.279C > T mutations are predicted to change the stability of the mRNA secondary structure by reducing the minimum free energy and are predicted to change the mRNA secondary structure of LEPR. Our findings may provide potentially useful genetic markers for increasing litter size in sheep.