Meta-analysis of association between c.963A>G single-nucleotide polymorphism on BMP15 gene and litter size in goats

Litter size is an important economic trait in the goat industry. Previous studies on the bone morphogenetic protein 15 (BMP15) gene detected some single-nucleotide polymorphisms (SNPs) such as c.963A $$ G that were associated with an increase in ovulation rate and litter size. The aim of this study was to conduct a meta-analysis on the effect of this polymorphism on litter size. We gathered and pooled data from five eligible published studies. To investigate the effect of c.963A $$ G on litter size, we utilized four different genetic models assuming dominant (GG  $$  GA vs. AA), recessive (GG vs. GA  $$  AA), additive (GG vs. AA) and co-dominant (GG  $$  AA vs. GA) model of inheritance. Data were analyzed under random-effects models based on the $$ value. Furthermore, sensitivity analysis was carried out to validate the stability of results. The results showed that the c.963A $$ G polymorphism is associated with litter size when applying a dominant model (standardized mean difference (SMD) is 0.815, 95 % CI [0.170, 1.461], $$  value  $$  0.013) and also with an additive model (SMD  $$  0.755, 95 % CI [0.111, 1.400], $$  value  $$  0.022). However, the effect of c.963A $$ G polymorphism was not significant under recessive (SMD  $$  0.186, 95 % CI [ $$ 0.195, 4.259], $$  value  $$  0.339) and co-dominant (SMD  $$   $$ 0.119, 95 % CI [ $$ 0.525, 0.288], $$  value  $$  0.568) models. Sensitivity analysis demonstrated that dropping studies with wide confidence intervals affects overall results under the assumption of an additive model. The meta-analysis results revealed that the AA genotype could be positively connected with litter size in goats.