Endometriosis and RAS System Gene Polymorphisms: The Association of ACE A2350G Polymorphism with Endometriosis in Polish Individuals

Abstract

To analyze the polymorphisms of angiotensin I converting enzyme (ACE) gene (insertion/deletion [I/D], A2350G) and angiotensin II type 1 receptor gene (A1166C) in women with endometriosis and to determine the correlation of the identified genotypes with the severity of the disease. Additionally, to estimate the prognostic value of the polymorphisms in patients with endometriosis treated due to infertility. The study group included 241 women, the control group (without endometriosis)—127. The molecular analysis was performed by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism technique. For I/D ACE and A1166C AT1 polymorphisms no significant differences were observed between the study and control groups and between the severity grades of the disease (p>0.05). For A2350G ACE polymorphism the frequency of genotypes for the study and control groups respectively was the following: AA—31.54%, AG—54.36%, GG—14.11% and AA—55.12%, AG—36.22%, GG—8.66% (x ²=19.36, p<0.0001). Statistically significant differences were found between the frequency of A and G alleles between both groups (x ²=15.16, p=0.0001), but not when individual grades of the disease severity were compared. There was no association between the investigated polymorphisms and the effect of infertility treatment. A2350G polymorphism (allele G, AG genotype) of ACE gene seems to be associated with the development of endometriosis.

Introduction

Endometriosis is a gynecological disease affecting about 10% of women during reproductive years, but as many as 35–70% of women with pain within pelvis minor or with infertility (Gazvani and Tempelton, 2002; Vigano et al., 2004; Ozkan et al., 2008; Triolo et al., 2013). Endometrial tissues are found outside the uterus. The lesions are most frequently located in pelvis minor and in parietal peritoneum, however, there are cases where they are observed in pericardium or in the pleura (Hompes and Mijatovic, 2007; Baldi et al., 2008). The main symptoms of endometriosis and the causes of its treatment include acute menstrual and premenstrual pain, chronic pain within pelvis minor, dyspareunia, and infertility (Hompes and Mijatovic, 2007).

Etiology of endometriosis still remains unclear, although there are several theories trying to explain the pathogenesis of this disease. According to the theory of implantation, fragments of endometrium together with menstrual fluid penetrate through the fallopian tubes to the peritoneum and pelvis minor where it comes to implantation and to the onset of the disease. In turn, according to the theory of metaplasia, coelomic epithelial cells undergo metaplastic transformation to endometrial cells. In rare cases of the development of endometriosis in women with congenital absence of the uterus and in men, uterine epithelium cannot be the source of ectopic endometrium and hence the metaplasia theory may explain these cases (Nap et al., 2004; Signorile and Baldi, 2010; Macer and Taylor, 2012). Further, small number of labors, short menstrual cycles, prolonged menstrual bleeding, and genetic predispositions are listed among factors favoring the occurrence of endometriosis (Gazvani and Tempelton, 2002). The role of angiogenesis in the development and persistence of the disease foci, which are very well vascularized, has been emphasized more and more frequently (Ryan and Taylor, 1997; Vigano et al., 2004; Barcz et al., 2006; Taylor et al., 2009).

The renin-angiotensin system (RAS), having a systemic and local actions in various tissues, is known to play a role in the process of blood vessels formation (Khakoo et al., 2008). RAS system includes genes encoding angiotensinogen (AGT), angiotensin II precursor molecule (the key element of this system), renin, angiotensin I converting enzyme (ACE), and angiotensin II type 1 and 2 receptor proteins (AT1 and AT2). Angiotensinogen is synthesized in liver, released into the circulation, and then renin carries out its conversion to angiotensin I. This decapeptide is a substrate for ACE, which after removal of the two end-terminal amino acids is converted to angiotensin II, an active component of RAS system, which affects the cells through AT1 and AT2 receptors (Crisan and Carr, 2000). RAS system promotes angiogenesis indirectly as the activated angiotensin II receptors stimulate vascular endothelial growth factor (VEGF) (Khakoo et al., 2008). Drugs blocking the activity of these receptors were demonstrated to reduce the tumor feeding and thus its growth (Fujita et al., 2002). As it has been mentioned above, the role of genetic factor is emphasized in the development of endometriosis. To date many candidate genes have been subjected to molecular analysis, including those engaged in the detoxication, encoding hormone receptors and enzymes synthesizing steroids, adhesion protein genes, cytokine and growth factor genes, tumor suppressor genes, cell cycle and mismatch repair genes and genes regulating vascular function and tissue remodeling [reviewed in Refs. (Montgomery et al., 2008; Trovó de Marqui, 2012)].

The aim of the study was to analyze insertion/deletion (I/D) and single nucleotide polymorphism (SNP) of angiotensin I converting enzyme (A2350G) and angiotensin II AT1 receptor SNP A1166C gene in women with diagnosed endometriosis and to determine the correlation of the identified genotypes with the severity and clinical course of the disease. Moreover, an attempt was made to evaluate the prognostic value of the detected RAS system gene polymorphisms in patients with endometriosis treated due to infertility.

Materials and Methods

Subjects

The study group included 241 women (mean age 32.2±6.0, range 17–52), diagnosed upon laparoscopic examination with different grades (I—minimal, II—mild, III—moderate, IV—severe) of endometriosis according to American Fertility Society (AFS) classification system (1979) which is characterized in Table 1. A cohort of 127 women without endometriosis (excluded upon laparoscopy) was studied as a control group (mean age 39.6±10.4, range 20–66) (Table 1).

Table 1.

Characteristics of the Study (Women with Endometriosis) and the Control Group

Endometriosis grade	Number of patients	Mean age	Range of age
I	56	31.8±5.0	21–45
II	52	33.5±6.1	24–52
III	75	32.4±6.9	17–50
IV	58	31.1±5.2	20–46
Total	241	32.2±6.0	17–52
Control group	127	39.6±10.4	20–66

All subjects were patients admitted to the Department of Surgical and Endoscopic Gynecology, Polish Mother's Memorial Hospital (Lodz, Poland). All participants provided written informed consent to participate in the study.

The protocol had been previously approved by the Bioethical Committee of the Medical University of Lodz (RNN/421/12/KB).

Molecular analysis

Peripheral venous blood samples were collected from women into tubes containing Na₂EDTA. Genomic DNA was extracted with the use of the Blood Mini kit (DNA-Gdańsk) according to the manufacturer's instructions.

ACE I/D polymorphism

A polymerase chain reaction (PCR) assay was performed to detect the ACE I/D polymorphism. The primers sequence was taken from Hsieh et al. (2007): forward 5′-CTGGAGACCACTCCCATCCTTTCT-3′, reverse 5′-GATGTGGCCATCACATTCGTCAGAT-3′. A total volume of 50 μL reaction mixture contains 150 ng of each primer, 0.1 mM of dNTPs, 1× PCR buffer, 1.5 U of Taq polymerase, and 50 ng of genomic DNA. The thermocycling conditions were as follows: 94°C for 5 min, 35 cycles of 94°C for 30 s, 62°C for 30 s, and 72°C for 45 s, followed by final extension at 72°C for 10 min (Genius, Techne). Amplicons were analyzed on a 2% agarose gel and stained with ethidium bromide. A Gene Ruler Low Range DNA Ladder (Fermentas) was used as the molecular size marker, and for ACE A2350G polymorphism. The two primers flank the polymorphic region of the ACE gene. The 490 bp product corresponds to insertion allele (I), whereas 190 bp to deletion allele (D).

ACE A2350G polymorphism

ACE A2350G polymorphism was detected by PCR restriction fragment length polymorphism (RFLP) assay. The used primers have sequences as follows: forward 5-CTGACGAATGTGATGGCCGC-3′, reverse 5′-TGATGAGTTCCACGTATTTCG-3′ (Hsieh et al., 2005). Reactions were performed with 75 ng of each primer, 0.2 mM of dNTPs, 0.5 mM of MgCl₂, 1× PCR buffer, 1 U of Taq polymerase, and 50 ng of genomic DNA in a final volume of 50 μL. After initial denaturation at 94°C for 5 min the DNA was amplified for 35 cycles with denaturation at 94°C for 30 s, annealing at 60°C for 30 s, and elongation at 72°C for 45 s. The final extension lasted 10 min (72°C) (Genius, Techne). The 122 bp PCR products were digested with 10 U od BstUI restriction enzyme (Fermentas) for 6 h at 37°C. Visualization of PCR products on 2% agarose gel should reveal a 122 bp fragment for the homozygotes (AA), 122 and 103 bp fragments for heterozygotes (AG), and 103 bp fragments for homozygotes (GG). The 19 bp fragment was not seen after digestion.

AT1 A1166C polymorphism

AT1 A1166C polymorphism was detected by PCR-RFLP assay. The forward and reverse primers sequences were 5′-AATGCTTGTAGCCAAAGTCACCT-3′ and 5′-GGCTTTGCTTTGTCTTGTTG-3′, respectively (Araújo et al., 2004). Every PCR sample contained 75 ng of each primer, 0.2 mM of dNTPs, 1 mM of MgCl₂, 1× PCR buffer, 1 U of Taq polymerase, and 50 ng of genomic DNA in a total volume of 50 μL. The thermocycling conditions were as follows: 94°C for 5 min, 35 cycles of 94°C for 30 s, 58.2°C for 1 min, and 72°C for 35 s, followed by 72°C for 7 min (Genius, Techne). PCR products were digested with 4 U of DdeI restriction endonuclease (Fermentas) for 5 h at 37°C. The amplicon with A is cleaved once by the enzyme, rendering two fragments (600 and 256 bp), whereas the C variant is cleaved twice (600, 146, and 110 bp). Restriction products were separated in 2% agarose gels, simultaneously with Gene Ruler 50 bp DNA ladder (Fermentas), stained with ethidium bromide.

Statistical analysis

Statistical analysis was performed using the Statistica 10.0 pl. The statistical analysis of genetic variables (allele and genotype frequencies between patients and control group, between different stages of endometriosis, and between other separated groups) was performed using the chi² test or Fisher's exact test. p<0.05 was considered statistically significant.

Results

To determine the effect of ACE gene polymorphisms (I/D and A2350G) and AT1 gene polymorphism (A1166C) on the development of endometriosis, 241 patients with diagnosed disease and 127 women from the control group were examined. The frequency of the analyzed genotypes in the case of ACE I/D and AT1 A1166C polymorphisms did not differ statistically significantly in the study and control group (respectively p=0.16, p=0.34) and within the study group between individual grades of disease severity (respectively p=0.34, p=0.97) (Table 2). Similarly, no statistically significant differences were noted in the frequency of individual alleles of the above-mentioned genes in the analyzed systems (Table 2). In the study group the distribution of the genotypes of ACE A2350G polymorphism were the following: AA—31.54%, AG—54.36%, and GG—14.11%, whereas in the control group: AA—55.12%, AG—36.22%, and GG—8.66%. The differences observed between the groups were statistically significant (x ²=19.36, p<0.001), the AG genotype occurred more frequently in the study group and AA genotype in the controls. There were also differences between the frequency of A and G alleles (x ²=15.16, p<0.001), where G allele was significantly more frequent in the study group and A allele in the controls (Table 2). However, no differences were found in the frequency of genotypes and alleles of ACE A2350G polymorphism between the grades of the disease severity (p>0.05) (Table 2).

Table 2.

Genotype and Allele Frequencies of ACE and AT1 Polymorphisms in Endometriosis Patients and Controls

	Controls (n=127), No. (%)	Patients endometriosis stage I–IV (n=241), No. (%)	p-Value ^a	Endometriosis stage I (n=56), No. (%)	Endometriosis stage II (n=52), No. (%)	Endometriosis stage III (n=75), No. (%)	Endometriosis stage IV (n=58), No. (%)	p-Value ^b
ACE polymorphisms
I/D genotypes			p=0.17					p=0.34
II	44 (34.65)	61 (25.31)		12 (21.43)	12 (23.08)	18 (24.00)	19 (32.76)
ID	55 (43.31)	118 (48.96)		32 (57.14)	21 (40.38)	38 (50.67)	27 (46.55)
DD	28 (22.05)	62 (25.73)		12 (21.43)	19 (36.54)	19 (25.33)	12 (20.69)
Allele			p=0.09					p=0.31
I	143 (56.30)	240 (49.79)		56 (50.00)	45 (43.27)	74 (49.33)	65 (56.03)
D	111 (43.70)	242 (50.21)		56 (50.00)	59 (56.73)	76 (50.67)	51 (43.97)
A2350G genotypes			p<0.0001					p=0.75
AA	70 (55.12)	76 (31.54)		18 (32.14)	18 (34.62)	20 (26.67)	20 (34.48)
AG	46 (36.22)	131 (54.36)		31 (55.36)	24 (46.15)	44 (58.67)	32 (55.17)
GG	11 (8.66)	34 (14.11)		7 (12.50)	10 (19.23)	11 (14.67)	6 (10.34)
Allele			p=0.0001					p=0.79
A	186 (73.23)	283 (58.71)		67 (59.82)	60 (57.69)	84 (56.00)	72 (62.07)
G	68 (26.77)	199 (41.29)		45 (40.18)	44 (42.31)	66 (44.00)	44 (37.93)
AT1 A1166C polymorphism			p=0.83					p=0.97
AA	70 (55.12)	125 (51.87)		31 (55.36)	25 (48.08)	39 (52.00)	30 (51.72)
AC	51 (40.16)	103 (42.74)		22 (39.29)	25 (48.08)	32 (42.67)	24 (41.38)
CC	6 (4.72)	13 (5.39)		3 (5.36)	2 (3.85)	4 (5.33)	4 (6.90)
Allele			p=0.56					p=0.11
A	191 (75.20)	353 (73.24)		84 (75.00)	75 (72.12)	110 (73.33)	84 (72.41)
C	63 (24.80)	129 (26.76)		28 (25.00)	29 (27.88)	40 (26.67)	32 (27.59)

p-value for the comparison of results between the study and control group.

p-value for the comparison of results between the grades of disease severity.

ACE, angiotensin I converting enzyme; I/D, insertion/deletion.

Due to lack of significant differences in the frequency of genotypes of the analyzed polymorphisms between grades of endometriosis severity, two groups of patients were distinguished within the study group: A (n=108), including women with grade I and II of the disease and B (n=133)—patients with grade III and IV of endometriosis acc. to AFS classification (1979). The frequency of examined genotypes and alleles is presented in Table 3. No significant differences were found in the analyzed polymorphisms between frequency of the genotypes and alleles (p>0.05).

Table 3.

Genotype and Allele Frequencies of ACE and AT1 Polymorphisms in Group A and B of Endometriosis Patients

	I+II grade of endometriosis (group A, n=108), No. (%)	III+IV grade of endometriosis (group B, n=133), No. (%)	p-Value
ACE polymorphisms
I/D genotypes			p=0.49
II	24 (22.22)	37 (27.82)
ID	53 (49.07)	65 (48.87)
DD	31 (28.70)	31 (23.31)
Allele			p=0.23
I	101 (46.76)	139 (52.26)
D	115 (53.24)	127 (47.74)
A2350G genotypes			p=0.61
AA	36 (33.33)	40 (30.08)
AG	55 (50.93)	76 (57.14)
GG	17 (15.74)	17 (12.78)
Allele			p=0.97
A	127 (58.80)	156 (58.65)
G	89 (41.20)	110 (41.35)
AT1 A1166C polymorphism			p=0.89
AA	56 (51.85)	69 (51.88)
AC	47 (43.52)	56 (42.11)
CC	5 (4.63)	8 (6.02)
Allele			p=0.87
A	159 (73.61)	194 (72.93)
C	57 (26.39)	72 (27.07)

Infertility accompanied endometriosis in a part of patients enrolled into the study group. They were subjected to surgical treatment (surgery and hormone therapy) to remove the disease foci. In the case of 49 women (group X), the undertaken therapy allows getting pregnant and carrying to term, in 60 (group Z) it was not successful. The characteristics of groups X and Z is presented in Table 4. Both groups were compared as regards the frequency of the analyzed polymorphisms. The test chi² did not demonstrate significant differences between the analyzed groups (Table 5).

Table 4.

Characteristics of Group X (Patients with Positive Effect of Infertility Treatment) and Z (Patients with Negative Effect of Infertility Treatment) According to the Stage of Endometriosis

	Endometriosis grade, No. (%)
	I	II	III	IV
Group X (n=49)	16 (32.65)	7 (14.29)	11 (22.45)	15 (30.61)
Group Z (n=60)	12 (20.00)	13 (21.67)	19 (31.67)	16 (26.67)

Table 5.

Genotype and Allele Frequencies of ACE and AT1 Polymorphisms in Endometriosis Patients with Positive and Negative Infertility Treatment Effect

	Positive infertility treatment effect (group X, n=49), No. (%)	Negative infertility treatment effect (group Z, n=60), No. (%)	p-Value
ACE polymorphisms
I/D genotypes			p=0.21
II	8 (16.33)	17 (28.33)
ID	28 (57.14)	25 (41.67)
DD	13 (26.53)	18 (30.00)
Allele			p=0.54
I	44 (44.90)	59 (49.17)
D	54 (55.10)	61 (50.83)
A2350G genotypes			p=0.17
AA	14 (28.57)	22 (36.67)
AG	33 (67.35)	31 (51.67)
GG	2 (4.08)	7 (11.67)
Allele			p=0.97
A	61 (62.24)	75 (62.50)
G	37 (37.76)	45 (37.50)
AT1 A1166C polymorphism			p=0.50
AA	29 (59.18)	35 (58.33)
AC	16 (32.65)	23 (38.33)
CC	4 (8.16)	2 (3.33)
Allele			p=0.73
A	74 (75.51)	93 (77.50)
C	24 (24.49)	27 (22.50)

Discussion

Studies have demonstrated that the process of neurovascularization plays an important role in the formation of ectopic endometriotic foci, which is confirmed by the fact that endometriotic implants are often surrounded by a dense web of blood vessels (Vigano et al., 2004; Taylor et al., 2009). The process of angiogenesis is controlled by many factors, among others by fibroblast growth factor 2 (FGF-2), transforming growth factor α (TGF-α), TGF-β, hepatocyte growth factor, tumor necrosis factor α (TNF-α), or VEGF (Yancopolous et al., 2000). It has been also proven that renin-angiotensin system plays a role in the formation of new blood vessels. In this case, stimulation of angiogenesis is indirect because activation of angiotensin II receptors induces VEGF expression, vasculo- and angiogenesis regulator (Heffelfinger, 2007; Khakoo et al., 2008). Additionally, Saijonmaa et al. (2001) demonstrated that VEGF induces endothelial cells to ACE synthesis and secretion, which in turn can induce angiotensin II synthesis, and thus VEGF and RAS system create a specific self-perpetuating system. To date several ACE gene polymorphisms have been described, including I/D of Alu sequence (287 bp) within intron 16 and SNP A2350G within exon 17 resulting in synonymous substitution Thr776Thr (Trovó de Marqui, 2012). According to the data published by Martínez et al. (2000) D allele in I/D polymorphism causes the increase of ACE activity in blood serum. In turn, Zhu et al. (2001) demonstrated similar dependence in the case of G allele of A2350G polymorphism, which caused the increase in ACE level and also the increase in blood pressure.

The investigated polymorphisms and the development of endometriosis

To date in the available literature two studies have appeared concerning the association of ACE I/D polymorphism with the development of endometriosis. Hsieh et al. (2007) examined 125 patients with grade III and IV of endometriosis and 128 patients from the control group. They found a strong correlation between the occurrence of I allele (both in homo- and heterozygotic system) and the development of endometriosis. In our study we examined 241 patients with endometriosis (I–IV grade) and 127 women from the control group. The results of the analysis of ACE I/D polymorphism were the following: II—25.31%, ID—48.96%, DD—25.73% and II—34.65%, ID—43.31%, DD—25.73%, respectively for the study and control group. Both, in the case of the analyzed genotypes and single alleles, no statistically significant differences were observed between the groups. Further, the comparison was made of the frequency of possible genotypes of ACE I/D polymorphisms between the grades of the disease severity (Table 2). The results of the comparison of these parameters were statistically insignificant (p=0.34). Similar results were obtained in our previous study comprising a smaller cohort of patients (121 women) (Kowalczyńska et al., 2011). The next stage of the analysis was to compare the frequency of genotypes of ACE I/D polymorphism between patients with I and II (group A, n=108) and III and IV (group B, n=133) grades of endometriosis. The frequency of genotypes was: II—22.22%, ID—49.07%, DD—28.70% and II—27.82%, ID—48.87%, DD—23.31%, respectively for the above described groups. The observed differences were insignificant. Our results did not show any correlation between ACE I/D polymorphism and the risk for the development of endometriosis, which is in conflict with the study published by Hsieh et al. (2007). Racial differences might be the cause of divergences (Caucasian vs. Asian race).

A single nucleotide A2350G polymorphism was the next tested ACE polymorphism. The following results were obtained: AA—31.54%, AG—54.36%, GG—14.11%, A—58.71%, G—41.29% and AA—55.12%, AG—36.22%, GG—8.66%, respectively for the study and control group. Our results demonstrated significant differences between both groups. G allele (x ²=15.16, p=0.0001) and AG genotype (x ²=19.36, p<0.0001) but not GG were significantly more frequent in women with endometriosis. The comparison of genotype frequency between the grades of disease severity and between group A (grade I and II endometriosis) and B (III and IV grade endometriosis) did not reveal significant differences (Table 3). Hsieh et al. (2005) obtained similar results for the group of 150 patients with grade III and IV of endometriosis compared with the control group of 159 women. According to these authors G allele, both in homo- and heterozygotic system, predisposes to the occurrence of the disease. Although ACE A2350G polymorphism leads to synonymous substitution (Thr776Thr), a positive effect was demonstrated of G allele on the level of angiotensin I convertase and on blood pressure (Zhu et al., 2001). Our results related to more frequent occurrence of G allele and AG genotype (p<0.0001) in women with endometriosis, thus they may point to the role of RAS system in the development of this disease.

On the other hand, the data published by Lamp et al. (2011) concerning 150 women with endometriosis and 199 women from the control group did not reveal the association between any genotype or allele of the tested ACE polymorphism and endometriosis. As the authors of these studies suggest, the differences in frequency of genotypes may result from ethnic divergences between the analyzed populations (Lamp et al., 2011).

Angiotensin II sends a signal into the cells via two types of membrane receptors AT1 and AT2. Angiotensin II was demonstrated (on animal cell systems and laboratory mice) to stimulate the synthesis of VEGF and its receptor VEGFR2 and thus the process of angiogenesis and this effect is inhibited by AT1 inhibitors (Heffelfinger, 2007; Imai et al., 2007). The polymorphism of adenine/cytosine transversion at the 1166 position (A1166C) is the most frequently investigated AT1 polymorphism. Bonnardeaux et al. (1994) observed a positive relationship between C allele of the discussed polymorphism and the development of hypertension in humans. The studies carried out by Nałogowska-Głośnicka et al. (2000) demonstrated the increase of risk for the occurrence of hypertension in pregnant women, carriers of CC genotype.

As far as we know, in literature there are no available studies concerning the analysis of angiotensin II type 1 AT1 receptor A1166C gene polymorphism in women with endometriosis. In our studies, the frequency of A1166C polymorphism genotypes and alleles was as follows: AA—51.87%, AC—42.74%, CC—5.39%; A—73.24%, C—26.76% and AA—55.12%, AC—40.16%, CC—4.72%; A—75.20%, C—24.80%, respectively for the study and control group. However, no statistically significant differences were observed in their frequency in both investigated groups (Table 2). The comparison of frequency of the above-mentioned genotypes and alleles between grades of endometriosis severity between group A (grade I and II) and B (grade III and IV) did not demonstrate significant differences, either (Table 3). Thus, our results suggest the lack of relationship between AT1 receptor gene A1166C polymorphism and the development of endometriosis.

The tested polymorphisms and infertility in endometriosis

Endometriosis is often diagnosed while searching for the causes of inability to become pregnant. In the case of grade III and IV of disease severity, infertility often results from anatomical changes induced by disease foci within reproductive organs. In patients with grade I and II endometriosis the causes of infertility are less obvious. One of the theories explaining this phenomenon supposes that inflammatory processes within peritoneal space decrease normal fertility (Halis and Arici, 2004). The therapy of infertility associated with endometriosis lies in surgical removal of the disease foci to restore normal anatomy in peritoneal space. Then, immediate pregnancy is recommended or postoperative hormone therapy is introduced to eliminate the remaining disease foci and modification of menstrual cycle to stop monthly bleeding and in this way to create environment unfavorable for the development of endometriotic lesions (Ozkan et al., 2008). The management is mainly conditioned by the patient's age, wish to become pregnant, and grade of disease severity.

In our study, infertility concerned most of the patients enrolled to the study group (n=161, 66.80%) and that was the reason of their treatment. We managed to get information about the efficacy of the applied therapy from 109 patients and in 49 (44.95%, group X) of them the effect was positive while in the remaining 60 patients (55.05%, group Z) the treatment was ineffective. Both groups were compared as regards the genotype frequency of the analyzed ACE (I/D, A2350G) and AT1 (A1166C) gene polymorphisms to determine whether there was a correlation between the genotypes and the efficacy of the therapy of infertility associated with endometriosis. Our results did not show significant differences between group X and Z for the above analyzed genotypes (Table 5). Basing on them, it can be assumed that ACE I/D and A2350G and AT1 A1166C polymorphisms do not present prognostic value related to the expected effect of the treatment of infertility coexisting with endometriosis. However, this hypothesis should be confirmed in a larger cohort of patients.

Conclusions

In the studies carried out by us and related to selected genes of RAS system, only ACE A2350G polymorphism seems to be associated with the development of endometriosis. However, the prognostic value of the analyzed polymorphisms as regards the expected effect of the treatment of infertility accompanying the disease has not been demonstrated.

Footnotes

Acknowledgment

This study was supported by the Medical University of Lodz, Poland (project no. 502-03/5-102-03/502-54-069).

Disclosure Statement

No competing financial interests exist.

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