Abstract
Abstract Objectives: to review studies that used case-control design to verify the association of polymorphisms in VEGF and KDR genes in the development of endometriosis. Methods: the systematic review selected articles published until September 1, 2015 from PubMed, MEDLINE, BVS, SciELO databases, considering the following key words: endometriosis and ("polymorphism" or "SNP" or "genetic polymorphism") and ("VEGF" OR "Vascular endothelial growth factor" or "VEGFR-2" or "Vascular endothelial growth factor-2" or "KDR" or "Kinase Insert Domain Receptor"). Results: 106 articles were identified, only 11 were eligible. Discrepant results were observed regarding polymorphisms in VEGF gene in the development of endometriosis, which can be explained by methodological differences, sample size, eligible control type, using the unadjusted risk estimates and the heterogeneity of the studied population. Only one study investigated polymorphisms in KDR gene in the development of endometriosis, however it was ineligible for this review. Conclusions: to avoid discrepancy in the results, we suggest that the ideal control group should be formed by fertile women and free of gynecological diseases. Multicentric studies with adequate design, involving different population besides the combined analysis on polymorphisms in VEGF and KDR genes are still necessary to contribute in the understanding of this disease, which are social, clinical and economical problems.
Highlights
Endometriosis is a gynecological disease characterized by the presence of functional endometrial tissue outside the uterine cavity, representing one of the most common gynecological disorders.[1]
14 studies were excluded: 5 because they were meta-analyzes, 2 because they were reviews, one because it was a criticism on the meta-analysis published before, one because it explored single nucleotide polymorphisms (SNPs) in IL-10 gene instead of polymorphisms in vascular endothelial growth factor (VEGF) and/or KDR genes, 4 because they studied patients with adenomyosis and one because it evaluated women with pterygium instead of patients with endometriosis
11 case-control studies were included in this review that evaluated SNPs only in VEGF gene susceptibility to develop endometriosis from 2005 to 2015.8,21,23,24,26,27,3133,36,37 In relation to evaluate the quality of studies selected for this review, all the articles reached a percentage greater than 50%38 and the average score ranged between to 21 points (5596%)
Summary
Endometriosis is a gynecological disease characterized by the presence of functional endometrial tissue outside the uterine cavity, representing one of the most common gynecological disorders.[1]. The most widely accepted theory until today is Sampsons proposal,[10] who described that the endometrial tissue, by backward menstrual flow, returns to the uterine tubes and adheres to the peritoneal cavity For this to occur, the angiogenesis process is essential and it is characterized by the growth of new blood vessels from pre-existing ones.[11] Among the pro-angiogenic factors, the vascular endothelial growth factor (VEGF) is highlighted and plays an important role in the development of endometriosis.[11] In 2008, our group observed an increased distribution of VEGF and its receptor VEGFR-2 in samples of endometriosis of the ovary, bladder and the recto-sigmoid, when it was compared to control and the largest distribution of VEGF and VEGFR-2 was observed in the endometriosis of the recto-sigmoid,which is the most severe.[12]
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