GREM1 (gremlin1) is a known inhibitor for BMP15 (bone morphogenetic protein 15) family, but its genetic diversity in sheep is unknown. The present study was conducted to analyze the polymorphism of GREM1 gene using PCR- single-strand conformation polymorphism (SSCP) and DNA sequencing methods and to assess the possible association of GREM1 gene polymorphism with reproductive traits in Awassi ewes. A total of 224 ewes, 124 producing singles and 100 producing twins, were included in the study. Two SSCP patterns were detected in two amplified loci within the exon 2. Two exonic novel single nucleotide polymorphism (SNP)s were identified, c.74 T > G (the silent SNP p.Met123 =) and c.30 T > A with (the missense SNP p.Ile237Phe). Statistical analyses indicated a non-significant (P > 0.05) association of p.Met123 = with the analyzed reproductive traits of fecundity, prolificacy, litter size, and twinning rate. Meanwhile, p.Ile237Phe SNP exhibited a highly significant (P < 0.01) association with the measured reproductive traits, in which ewes with TA genotype (with p.Ile237Phe SNP) exhibited higher litter size, twinning ratio, fecundity, and prolificacy than those with TT genotype (without p.Ile237Phe SNP). The deleterious impact of p.Ile237Phe SNP was observed by the means of ten different state-of-the-art in silico tools that predicted a highly damaging effect of p.Ile237Phe SNP on the structure, function, and stability of gremlin1. In conclusion, the results of our study suggest that p.Ile237Phe SNP has a remarkable negative impact on the gremlin1 structure, function, and stability. Since gremlin1 is a known inhibitor of reproductive performance, a consequent higher reproductive performance was observed in ewes with damaged gremlin1 (with p.Ile237Phe SNP) than those with non-damaged gremlin1 (without p.Ile237Phe SNP). Therefore, it can be stated that the implementation of the novel p.Ile237Phe SNP in the GREM1 gene could be a useful marker in marker-assisted selection. This manuscript is the first one to describe GREM1 gene variations in sheep.

GREM1（gremlin1）是BMP15（骨形态发生蛋白15）家族的一种已知抑制剂，但其在绵羊中的遗传多样性尚不清楚。本研究旨在通过PCR单链构象多态性（SSCP）和DNA测序方法分析GREM1基因的多态性，并评估GREM1的可能关联性。Awassi母羊具有生殖性状的基因多态性。这项研究总共包括224头母羊，其中124头为单打母羊，100头为双胞胎。在外显子2的两个扩增基因座中检测到两个SSCP模式。鉴定出两个外显子新颖的单核苷酸多态性（SNP），c.74 T> G（沉默SNP p.Met123 =）和c.30 T> A，其中（错义SNP p.Ile237Phe）。统计分析表明 ，p.Met123 =与分析的繁殖力，繁殖力，产仔数和孪生率的无显着相关性（P > 0.05）。同时，p.Ile237Phe SNP表现出高度显着性（P <0.01）与测得的生殖性状相关，其中TA基因型（p.Ile237Phe SNP）的母猪比TT基因型（无p.Ile237Phe SNP）的母猪有更高的产仔数，孪生率，繁殖力和繁殖能力。p.Ile237Phe SNP的有害影响是通过十种不同的计算机软件手段观察到的，这些工具预测了p.Ile237Phe SNP对gremlin1的结构，功能和稳定性具有高度破坏性。总之，我们的研究结果表明p.Ile237Phe SNP对gremlin1的结构，功能和稳定性具有显着的负面影响。由于gremlin1是已知的生殖性能抑制剂，因此，在损坏的gremlin1（使用p.Ile237Phe SNP）的母羊中观察到的生殖性能要比未损坏的gremlin1（未使用p.237）的母羊更高。Ile237Phe SNP）。因此，可以说新型p.Ile237Phe SNP在GREM1基因可能是标记辅助选择中的有用标记。该手稿是第一个描述绵羊GREM1基因变异的手稿。