ASSOCIATION OF GROWTH HORMONE RECEPTOR (GHR) GENE POLYMORPHISMS WITH BODY WEIGHT OF RABBITS: A SYSTEMATIC REVIEW AND META-ANALYSIS

Résumé

The growth hormone receptor (GHR) gene plays a key role in regulating growth and metabolism. However, the relationship between polymorphic variants of this gene and the body weight of rabbits under different genetic models has not been established. Thus, the objective of this study was to evaluate relationship between GHR gene polymorphisms and body weight of rabbits. Relevant literatures were systematically reviewed using the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) guideline. 248 studies were identified and screened against pre-determined inclusion criteria and data were extracted from 17 studies. Each study was subjected to Hardy-Weinberg Equilibrium (HWE) test and six genetic models consisting of co-dominant, dominant, recessive and over-dominant models were fitted using OpenMeta® Analyst Software. The Cohen’s d method was used to calculate standardized mean differences (SMDs) to estimate individual study effect size as well as the overall effect size. Heterogeneity measures were inferred from the Q statistic (based on Chi-square test) and its associated p-value, Tau-squared (τ²), H-squared (H²) and I-squared (I²) values. Publication bias was assessed by Egger’s regression asymmetry test and sensitivity analysis was conducted to detect if the overall effect size was largely due to a single study effect size. There was significant association (P<0.05) of GHR gene with body weight of rabbits under one of the co-dominant models (CG vs GG). However, this association was not significant (P>0.05) under all other genetic models. Further, the results indicated that, cumulatively for all studies included in the meta-analysis of association of GHR gene with body weight of rabbits, GG genotype had higher body weight than CG genotype. However, there was no difference (P>0.05) between CC and CG and CC and GG genotypes. These findings implied that the impact of GHR gene polymorphisms on body weight in rabbits may be influenced by specific genetic models.