Increased frequencies of cytochrome P4501A1 polymorphisms in infertile men

Genic-intergenic polymorphisms of CYP1A genes and their clinical impact

The humancytochrome P450 1A (CYP1A) subfamily genes, CYP1A1 and CYP1A2, encoding monooxygenases are critically involved in biotransformation of key endogenous substrates (estradiol, arachidonic acid, cholesterol) and exogenous compounds (smoke constituents, carcinogens, caffeine, therapeutic drugs). This suggests their significant involvement in multiple biological pathways with a primary role of maintaining endogenous homeostasis and xenobiotic detoxification. Large interindividual variability exist in CYP1A gene expression and/or catalytic activity of the enzyme, which is primarily due to the existence of polymorphic alleles which encode them. These polymorphisms (mainly single nucleotide polymorphisms, SNPs) have been extensively studied as susceptibility factors in a spectrum of clinical phenotypes. An in-depth understanding of the effects of polymorphic CYP1A genes on the differential metabolic activity and the resulting biological pathways is needed to explain the clinical implications of CYP1A polymorphisms. The present review is intended to provide an integrated understanding of CYP1A metabolic activity with unique substrate specificity and their involvement in physiological and pathophysiological roles. The article further emphasizes on the impact of widely studied CYP1A1 and CYP1A2 SNPs and their complex interaction with non-genetic factors like smoking and caffeine intake on multiple clinical phenotypes. Finally, we attempted to discuss the alterations in metabolism/physiology concerning the polymorphic CYP1A genes, which may underlie the reported clinical associations. This knowledge may provide insights into the disease pathogenesis, risk stratification, response to therapy and potential drug targets for individuals with certain CYP1A genotypes.

Association between CYP1A1 rs4646903 T > C genetic variations and male infertility risk: A meta-analysis

BACKGROUND

Number of studies have been performed to investigate the relationship between the CYP1A1 rs4646903 polymorphism and male infertility risk, but the sample size was small and the results were conflicting. A meta-analysis was performed to assess these associations.

METHODS

A systematic search was conducted to identify all relevant studies from Medline, Web of science, Embase, China biology medical literature database (CBM), China National Knowledge Infrastructure (CNKI), WanFang and Weipu (VIP) databases up to June 30, 2018. The odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the strength of associations. All of the statistical analyses were conducted using Revman 5.3 and Stata 14.0.

RESULTS

Ten studies involved 3028 cases and 3258 controls. Overall, significant association was observed between the CYP1A1 rs4646903 polymorphism and male infertility (C vs T: OR = 1.42, 95%CI = 1.14-1.76; CC vs TT: OR = 2.13, 95%CI = 1.36-3.34; CC vs CT+TT: OR = 1.96, 95%CI = 1.30-2.95; CC+CT vs TT: OR = 1.51, 95%CI = 1.16-1.97). In subgroup analysis by ethnic group, a statistically significant association was observed in Asians (C vs T: OR = 1.59, 95%CI = 1.22-2.08), but not in Non-Asians (C vs T: OR = 1.01, 95%CI = 0.79-1.30). Additionally, none of the individual studies significantly affected the association between CYP1A1 rs4646903 polymorphism and male infertility, according to sensitivity analysis.

CONCLUSION

Our meta-analysis supports that the CYP1A1 rs4646903 polymorphism might contribute to individual susceptibility to male infertility in Asians.

[Impact of lifestyle and environmental factors on male reproductive health]

The identification of potential environmental hazards may be clinically relevant in the diagnosis of male infertility. Knowledge about these factors will improve prevention of fertility disorders. Apart from drugs or factors related to lifestyle such as alcohol and tobacco smoke, various environmental and occupational agents, both chemical and physical, may impair male reproductive function. Reproductive toxicity may evolve at the hypothalamic-pituitary, testicular, or post-testicular level; endpoints comprise deterioration of spermatogenesis and sperm function as well as endocrine disorders and sexual dysfunction. With regard to the complex regulation of the male reproductive system, the available information concerning single exogenous factors and their mechanisms of action in humans is limited. This is also due to the fact that extrapolation of results obtained from experimental animal or in vitro studies remains difficult. Nevertheless, the assessment of relevant exposure to reproductive toxicants should be carefully evaluated during diagnostic procedures of andrological patients.

PrESOgenesis: A two-layer multi-label predictor for identifying fertility-related proteins using support vector machine and pseudo amino acid composition approach

Successful spermatogenesis and oogenesis are the two genetically independent processes preceding embryo development. To date, several fertility-related proteins have been described in mammalian species. Nevertheless, further studies are required to discover more proteins associated with the development of germ cells and embryogenesis in order to shed more light on the processes. This work builds on our previous software (OOgenesis_Pred), mainly focusing on algorithms beyond what was previously done, in particular new fertility-related proteins and their classes (embryogenesis, spermatogenesis and oogenesis) based on the support vector machine according to the concept of Chou's pseudo-amino acid composition features. The results of five-fold cross validation, as well as the independent test demonstrated that this method is capable of predicting the fertility-related proteins and their classes with accuracy of more than 80%. Moreover, by using feature selection methods, important properties of fertility-related proteins were identified that allowed for their accurate classification. Based on the proposed method, a two-layer classifier software, named as "PrESOgenesis" ( https://github.com/mrb20045/PrESOgenesis ) was developed. The tool identified a query sequence (protein or transcript) as fertility or non-fertility-related protein at the first layer and then classified the predicted fertility-related protein into different classes of embryogenesis, spermatogenesis or oogenesis at the second layer.

Potential Positive Association between Cytochrome P450 1A1 Gene Polymorphisms and Recurrent Pregnancy Loss: a Meta-Analysis

In order to discover the potential genetic risks associated with recurrent pregnancy loss (RPL), this meta-analysis was conducted to assess the association between CYP1A1 gene polymorphism and RPL. Studies were retrieved from the databases PubMed, Embase, HuGENet, and CNKI. Four models were then applied. Seven studies, including three datasets for the rs1048943 and five for the rs4646903 single-nucleotide polymorphism (SNP), were included in this analysis, involving 613 cases and 398 controls for the rs1048943; and 864 cases and 842 controls for the rs4646903 SNP. After comprehensive analysis, we found that rs4646903 was significantly associated with RPL [recessive (OR = 1.72, 95%CI: 1.13-2.61); codominant (CC vs TT; OR = 1.74, 95%CI: 1.12-2.71), (CC vs CT; OR = 1.67, 95%CI: 1.07-2.62) and allele analysis (OR = 1.27, 95%CI: 1.07-1.50)]. In the following subgroup analysis, a positive association was also discovered among people of Asian descent, especially South Asians. However, there was no obvious association between rs1048943 and RPL. In summary, our results suggest that CYP1A1 gene polymorphism (particularly for rs4646903) might be associated with RPL risk, especially among South Asians. Further studies are required to confirm this association.

Effect of CYP1A1 gene polymorphism and psychological distress on seminal analysis parameters

Background

Psychological factor alters fertility hormones and contributes to male infertility. Anxiety and depression are common manifestations of psychological distress. Cytochrome P-4501A1 (CYP1A1) metabolizes xenobiotics and fertility hormones that influence male fertility. The effect of CYP1A1 polymorphism on male fertility has remained controversial.

The present study was designed to assess the effect of psychological distress and CYP1A1 polymorphisms and their interactions on parameters of seminal analysis.

Methods

Eighty male partners of infertile couples were evaluated for level of distress using Hospital anxiety and depression score (HADS) questionnaire. As per WHO guidelines (2010), sperm count, motility and morphology were assessed and subjects were classified as (a) subjects having normal sperm characteristics and (b) subjects having abnormal sperm characteristics. CYP1A1 polymorphisms were detected by ASO-PCR.

Results

The significant odd’s ratio indicates that psychological distress (OR:10.54; CI:3.72–29.84; P < 0.001), CYP1A1*4(OR:10.31; CI:3.01–35.24; P < 0.001) and CYP1A1*2C (OR:7.01; CI:1.78–27.56; P = 0.002) polymorphisms are risk factors for the development of abnormal sperm characteristics in male subjects. Data analysis with two way ANOVA shows that psychological distress, CYP1A1*4 and CYP1A1*2C polymorphisms significantly affect but do not interact among them to influence sperm parameters.

Conclusions

It is concluded that CYP1A1 gene polymorphisms and psychological distress act independently but do not interact with each other in pathogenesis of male infertility.

CYP1A1 3801T>C polymorphism implicated in altered xenobiotic metabolism is not associated with variations in sperm production and function as measured by total motile sperm and fertilization rates with intracytoplasmic sperm injection

OBJECTIVE

To evaluate the cytochrome P450 3801T>C polymorphism's frequency in relation to semen production, as determined by semen analysis parameters, and sperm function, as determined by fertilization rates with intracytoplasmic sperm injection (ICSI).

DESIGN

Case-control study.

SETTING

Academic-affiliated private practice.

PATIENT(S)

This study included patients undergoing IVF from 2004 to 2014 grouped into categories based on semen analysis parameters performed at a single andrology laboratory. Cases were patients with total motile sperm (TMS) counts of ≤20 × 10(6). Frequency-matched controls were selected with TMS of >20 × 10(6).

INTERVENTION(S)

The 3801T>C polymorphism was identified using DNA from serum samples with real-time quantitative polymerase chain reaction.

MAIN OUTCOME MEASURE(S)

CYP1A1 3801T>C polymorphism frequency in TMS groups and distribution in fertilization rate outcomes with ICSI.

RESULT(S)

A total of 460 cases were identified with ≤20 × 10(6) TMS, and 489 age-matched controls with >20 × 10(6) TMS were selected across the study time frame. For those with <5 × 10(6) vs. >20 × 10(6) TMS there was no difference when comparing heterozygous (odds ratio [OR] 0.96; 95% confidence interval [CI] 0.66-1.40) or homozygous mutant (OR 1.33; 95% CI 0.52-3.20) with the wild-type patients. Additionally, no difference was seen when analyzing subgroups <5 × 10(6), 5-20 × 10(6), and >20 × 10(6) TMS in a similar fashion. Receiver operating characteristic (ROC) curve analysis did not find a significant TMS count based on presence of the polymorphism (area under the ROC curve = 0.51). There were 460 patients who underwent IVF/ICSI, and fertilization rates did not differ with presence of the polymorphism (area under the ROC curve = 0.50).

CONCLUSION(S)

Allele frequency of the 3801T>C polymorphism does not correlate with semen production as determined by TMS counts or sperm function as determined by fertilization rates with ICSI. The use of neither semen analysis parameters nor fertilization rates with ICSI helps identify CYP1A1 polymorphism carriers.

Cytochrome P450-2D6*4 polymorphism seminal relationship in infertile men

This study aimed to assess cytochrome (CY) P450-2D6*4 polymorphism relationship with semen variables in infertile men. In all, 308 men were included; fertile normozoospermia (N) (n = 77), asthenozoospermia (A) (n = 70), asthenoteratozoospermia (AT) (n = 75) and oligoasthenoteratozoospermia (OAT) (n = 86). They were subjected to history taking, clinical examination, semen analysis, sperm acrosin activity, seminal malondialdehyde (MDA) and CYP450-2D6*4 genotyping. CYP450-2D6*4 wild-type allele was represented in 76.5% of N, 70% of A, 66.7% of AT and 57.7% of OAT men where homozygous gene mutation was present in 5.9% of N, 20% of A, 26.6% of AT and 26.9% of OAT men, respectively. Sperm acrosin activity, sperm concentration, sperm motility, linear sperm velocity and sperm normal forms were significantly higher, and seminal MDA level was significantly lower in men with CYP450-2D6*4 wild-type allele compared with men with homozygous mutation. It is concluded that CYP450-2D6*4 wild-type allele has higher frequency where homozygous-type allele has lower frequency in N men compared with A, AT and OAT men. Sperm acrosin activity index, sperm concentration, sperm motility, linear sperm velocity and sperm normal forms were significantly higher, and seminal MDA level was significantly lower in men with CYP450-2D6*4 wild-type allele compared with men with homozygous mutation.

Meta-analysis of the association of oestrogen receptor-beta gene RsaI (G/A) and AluI (A/G) polymorphisms with male infertility

A more precise assessment of association of oestrogen receptor-beta genes RsaI(G/A) and AluI(A/G) polymorphisms with male infertility from current contradictory results is the aim of this meta-analysis including five RsaI and six AluI studies respectively. No association was observed between infertility and RsaI or AluI. In the stratified analysis by ethnicity, increased risk was found among Caucasians with GA versus GG (OR = 2.263, 95% CI = 1.073-4.776, I(2)  = 57.1%) and dominant model (OR = 2.117, 95% CI = 1.018-4.403, I(2)  = 49.0%) of RsaI. It was not observed for AluI. In the stratified analysis by infertility subtypes, a reduced risk in GA of AluI was observed among azoospermia or severe oligospermia (GA versus AA: OR = 0.686, 95% CI = 0.498-0.945, I(2)  = 21.2%; recessive model: OR = 1.403, 95% CI = 1.056-1.864, I(2)  = 31.7%), and reduced risk was in recessive model (OR = 0.650, 95% CI = 0.446-0.948, I(2)  = 0.0%) of subtypes, except for azoospermia or severe oligospermia. However, this finding was not observed in RsaI. The meta-analysis showed GA and GG of AluI are possibly resistant factors for spermatogenesis dysfunction and deteriorated sperm quality.

Association between 3801T>C polymorphism of CYP1A1 and idiopathic male infertility risk: a systematic review and meta-analysis

BACKGROUND

Epidemiological studies have evaluated the association between 3801T>C polymorphism of CYP1A1 gene and the risk for idiopathic male infertility, but the results are inconclusive. We aimed to derive a more precise estimation of the relationship by conducting a meta-analysis of case-control studies.

METHODS

This study conformed to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed, Embase and CNKI databases were searched through November 2013 to identify relevant studies. Pooled odds ratios with 95% confidence intervals were used to assess the strength of the association between CYP1A1 3801T>C polymorphism and idiopathic male infertility risk. Q-test was performed to evaluate between-study heterogeneity and publication bias was appraised using funnel plots. Sensitivity analyses were conducted to evaluate the robustness of meta-analysis findings.

RESULTS

Six studies involving 1,060 cases and 1,225 controls were included in this meta-analysis. Overall, significant associations between 3801T>C polymorphism and idiopathic male infertility risk were observed in allelic comparison (OR = 1.36, 95% CI: 1.01-1.83), homozygous model (OR = 2.18, 95% CI: 1.15-4.12), and recessive model (OR = 1.86, 95% CI: 1.09-3.20), with robust findings according to sensitivity analyses. However, subgroup analyses did not further identify the susceptibility to idiopathic male infertility in all comparisons. Funnel plot inspections did not reveal evidence of publication bias.

CONCLUSIONS

The current meta-analysis provides evidence of a significant association between CYP1A1 3801T>C polymorphism and idiopathic male infertility risk. Considering the limitation inherited from the eligible studies, further confirmation in large-scale and well-designed studies is needed.

Smoking status modifies the relation between CYP1A1*2C gene polymorphism and idiopathic male infertility: the importance of gene-environment interaction analysis for genetic studies of the disease

The study was designed to investigate the associations of polymorphisms Ile462Val and 3801T>C of the cytochrome P450 1A1 (CYP1A1) gene with idiopathic male infertility (IMI) and to assess the impact of smoking status on the relationship between the polymorphisms and the susceptibility to the disease. DNA samples from 203 patients with IMI and 227 fertile men were genotyped for the polymorphisms by a polymerase chain reaction and restriction fragment length polymorphism methods. We found for the first time that the increased risk of IMI in carriers of genotype 462Ile/Val of the CYP1A1 gene occurred only in smoker men (odds ratio [OR] = 1.91; 95% confidence interval [CI] 1.01-3.59), whereas nonsmoker men did not have the risk of infertility (OR = 1.58; 95% CI 0.66-3.76). The results of our study demonstrate that the analysis of gene-environment interactions is necessary to explain conflicting results of genetic studies of IMI and to improve our understanding of the mechanisms of the disease.

Genetic causes of spermatogenic failure

Approximately 10%-15% of couples are infertile, and a male factor is involved in almost half of these cases. This observation is due in part to defects in spermatogenesis, and the underlying causes, including genetic abnormalities, remain largely unknown. Until recently, the only genetic tests used in the diagnosis of male infertility were aimed at detecting the presence of microdeletions of the long arm of the Y chromosome and/or chromosomal abnormalities. Various other single-gene or polygenic defects have been proposed to be involved in male fertility. However, their causative effects often remain unproven. The recent evolution in the development of whole-genome-based techniques and the large-scale analysis of mouse models might help in this process. Through knockout mouse models, at least 388 genes have been shown to be associated with spermatogenesis in mice. However, problems often arise when translating this information from mice to humans.

Quantitative trait analysis suggests polymorphisms of estrogen-related genes regulate human sperm concentrations and motility

BACKGROUND

Human spermatogenesis is regulated by complex networks, and estrogens are recognized as one of the significant regulators of spermatogenesis. We tested the associations between variants of estrogen-related genes and semen parameters.

METHODS

We performed genotyping for genetic variants of estrogen-related genes and quantitative trait analysis of fertile and infertile men with well-characterized reproductive phenotypes. Men with known semen parameters (n= 677) were enrolled, including 210 fertile men and 467 infertile men. A total of 17 genetic markers from 10 genes, including 2 estrogen receptors (ER-α, ER-β), 7 estrogen synthesizing/metabolizing genes (CYP19A1, HSD17B1, CYP1A1, CYP1B1, COMT, GSTM1, GSTT1) and 1 transport gene (SHBG) were genotyped. Sperm concentration, motility and morphology were taken as quantitative traits to correlate with genetic variants in the estrogen-related genes.

RESULTS

Five genes (rs1801132 and rs2228480 of the ER-α gene, rs1256049 and rs4986938 of the ER-β gene, rs605059 of the HSD17B1 gene, rs1799941 of the SHBG gene and rs1048943 and rs4646903 of the CYP1A1 gene) were found to be significantly associated with sperm concentration (P< 0.01), while five genes (rs1801132 of the ER-a gene, rs1256049 of the ER-β gene, rs1048943 of the CYP1A1 gene, rs605059 of the HSD17B1 gene and rs1799941 along with rs6259 of the SHBG gene) were associated with sperm motility (P< 0.01). None of the estrogen-related genes were associated with sperm morphology. With an increasing number of risk alleles, sperm concentration and motility tended to deteriorate and show a loci-dosage effect.

CONCLUSIONS

Quantitative trait analysis based on a limited number of genetic markers suggests that estrogen-related genes mainly regulate sperm concentration and motility.

Association of CYP1A1 Gene Polymorphism with Ischemic Stroke in South Indian Population

Stroke is a major cause of morbidity and mortality worldwide. Genetic and environmental factors are involved in the pathogenesis of stroke. Hypertension, diabetes mellitus, and cigarette smoking are the major risk factors, and smoking doubles the risk of ischemic stroke. Smoking cessation decreased the risk for ischemic stroke. CYP1A1 is the phase I metabolizing enzyme which plays a key role in metabolic activation of polycyclic aromatic hydrocarbons which are present in cigarette smoke and considered carcinogenic. So far, the association of CYP1A1 gene polymorphism with stroke has not been investigated in Indian population. So, the study is taken up to evaluate the association of this polymorphism with ischemic stroke in a South Indian population. We genotyped 215 ischemic stroke patients and 162 age-matched controls using polymerase chain reaction-restriction fragment length polymorphism. Statistical analysis showed that CYP1A1 "CC" genotype is associated with five times increased risk of ischemic stroke (odds ratio (OR) = 5.14; 95% confidence interval (95% CI) = 1.14-23.14, p = 0.01), while "TT" (OR = 0.78, 95% CI = 0.51-1.19, p = 0.25) and "TC" (OR = 1.04, 95% CI = 0.67-1.60, p = 0.85) genotypes were nonsignificant with the increased risk of stroke. T and C allele frequencies in stroke were 76.5% and 23.5% as against 81.8% and 18.2% in control group, respectively, thus, suggesting no statistically significant differences in the T (OR = 0.72, 95% CI = 0.50-1.03, p = 0.07) and C (OR = 1.37, 95% CI = 0.96-1.97, p = 0.07) allele frequencies between the two groups. The distribution of CYP1A1 genotypes and allelic frequency within the stroke subtypes showed a significant association of CC genotype only in intracranial large artery atherosclerosis (OR = 5.21, 95% CI = 1.03-26.38, p = 0.02) while other subtypes did not show any association. Further analysis of CYP1A1 genotypes in patients and control subjects with smoking habit also showed a similar trend. Hence, we conclude that the CYP1A1 CC genotype is associated with the increased risk of ischemic stroke.

The search for SNPs, CNVs, and epigenetic variants associated with the complex disease of male infertility

Understanding the genetic basis of idiopathic male infertility has long been the focus of many researchers. Numerous recent studies have attempted to identify relevant single nucleotide polymorphisms (SNPs) through medical re-sequencing studies in which candidate genes are sequenced in large numbers of cases and controls in the search for risk or causative polymorphisms. Two major characteristics have limited the utility of the re-sequencing studies. First, reported SNPs have only accounted for a small percentage of idiopathic male infertility. Second, SNPs reported to have an association with male infertility based on gene re-sequencing studies often fail validation in follow-up studies. Recent advances in the tools available for genetic studies have enabled interrogation of the entire genome in search of common, and more recently, rare variants. In this review, we discuss the progress of studies on genetic and epigenetic variants of male infertility as well as future directions that we predict will be the most productive in identifying the genetic basis for male factor infertility based on our current state of knowledge in this field as well as lessons learned about the genetic basis for complex diseases from other disease models.

Association of CYP1A1*2A polymorphism with male infertility in Indian population

BACKGROUND

The CYP1A1 gene is a polymorphic gene and encodes for the CYP1A1 enzyme that catalyzes the bioactivation of polycyclic aromatic hydrocarbons (PAHs). PAHs are ubiquitous pollutants in the natural environment, which are capable of forming DNA adducts once being activated to generate DNA reactive metabolites. DNA adducts in sperm cells could be considered as a sign of severe DNA damage, which played an important role in meiotic division during spermatogenesis and could be associated with infertility. Lipophilic compounds undergo metabolic activation by phase I enzymes, which introduce a reactive center into the molecule, followed by phase II conjugation reaction resulting in a water soluble product.

METHODS

We genotyped CYP1A1*2A, using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay in a hospital based case-control study including 206 infertile men and 230 healthy fertile (control) subjects.

RESULTS

Analysis showed that CYP1A1*2A CC genotype is associated with increased risk of male infertility (OR=6.08, 95% CI=1.91-25.27), while TC genotype showed a non-significantly increased risk of male infertility (OR=1.35 95% CI=0.89-2.05). Further, when the variant genotypes were combined (CYP1A1*2A TC+CC) assuming a co-dominant allele effect, TC plus CC genotypes were also found to be significant with increased risk of male infertility (OR=1.57 95% CI=1.05-2.35 p=0.02). Allele frequencies are calculated for each genotype of CYP1A1*2A and the differences for allele frequencies between the infertile and fertile men are determined using Fisher's exact test. T and C allele frequencies in infertile men are 71% and 29% as against 80% and 20% in fertile men. The differences for allele frequencies are found to be statistically significant (p=0.002). The results showed a drastic decrease in the sperm count and motility and increase in dead sperms in CC genotype when compared to other genotypes in infertile men.

CONCLUSION

Based on Indian study we conclude that CC genotype of CYP1A1 is associated in the pathogenesis of male infertility.

Association of USP26 haplotypes in men in Taiwan, China with severe spermatogenic defect

AIM

To complete comprehensive haplotype analysis of USP26 for both fertile and infertile men.

METHODS

Two hundred infertile men with severe oligospermia or non-obstructive azoospermia were subjected to sequence analysis for the entire coding sequences of the USP26 gene. Two hundred men with proven fertility were genotyped by primer extension methods. Allele/genotype frequencies, linkage disequilibrium (LD) characteristics and haplotypes of fertile men were compared with infertile men.

RESULTS

The allele frequencies of five single nucleotide polymorphisms (370-371insACA, 494T>C, 576G>A, ss6202791C>T, 1737G>A) were significantly higher in infertile patients than control subjects. The major haplotypes in infertile men were TACCGA (28% of the population), TGCCGA (15%), TACCAA (8%), TGCCAA (6%), TATCAA (5%) and CATCAA (5%). The major haplotypes for the control subjects were TACCGA (58% of the population), CACCGA (7%), CATCGA (6%) and TGCCGA (5%). Haplotypes TGCCGA, TATCAA, CATCAA, CATCGC, TACCAA and TGCCAA were over-transmitted in patients with spermatogenic defect, whereas haplotypes TACCGA, CACCGA, and CATCGA were under-transmitted in these patients.

CONCLUSION

Some USP26 alleles and haplotypes are associated with spermatogenic defect in the Han nationality in Taiwan, China.

Polymorphisms of estrogen-related genes jointly confer susceptibility to human spermatogenic defect

OBJECTIVE

To establish a multilocus model for studying the effect of estrogen-related genes on impaired spermatogenesis.

DESIGN

Prospective study.

SETTING

University-based reproductive clinics and genetics laboratory.

PATIENT(S)

A total of 183 oligozoospermatic (sperm count <20 x 10(6)/mL) or azoospermatic males and 120 fertile control males were included.

INTERVENTION(S)

A total of 16 single nucleotide polymorphisms (SNPs) from nine genes (estrogen receptors [ER-alpha, ER-beta], estrogen synthesizing/metabolizing genes [CYP17, CYP19A1, HSD17B2, CYP1A1, CYP1B1, COMT], and transport genes [SHBG]) were genotyped. The combinatorial effect of multiple genetic variants was assessed using the multilocus model.

MAIN OUTCOME MEASURE(S)

Significantly associated SNPs and odds ratio (OR).

RESULT(S)

Six SNPs from five genes (rs180113 of ER-alpha gene, rs1256049 of ER-beta gene, rs1048943 of CYP1A1 gene, rs8191246 of HSD17B2 gene, and rs1799941 along with rs6259 of SHBG gene) were found to be significantly associated with spermatogenic defect. The genes were further divided into three categories according to their functions (receptors, synthesis and metabolism, and transporter). Based on our multilocus risk model, men with risk alleles in two of the three gene families had increased risk of impaired sperm production (OR = 10.5). The OR further increased to 34.6 for men with unfavorable alleles for all three gene families.

CONCLUSION(S)

Polymorphisms of estrogen-related genes jointly confer susceptibility to human spermatogenic defect at the prereceptor, receptor, and postreceptor levels in the Taiwanese Han population.

Polymorphisms in CYP1A1 gene are associated with male infertility in a Chinese population

Cytochrome P4501A1 (CYP1A1) is a key enzyme in phase I bioactivation of polycyclic aromatic hydrocarbons (PAHs), which have potential reproductive toxicity. The aim of this study was to investigate the association of the CYP1A1 polymorphisms with male infertility in a Han-Chinese population. We genotyped two polymorphisms, CYP1A1*2A and CYP1A1*2C, using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay in a hospital-based case-control study including 192 infertile patients with non-obstructive azoospermia or severe oligozoospermia and 226 fertile controls. We found that the genotype distribution of CYP1A1*2C was significantly different between the patients and the controls (p = 0.019). Analysis showed that CYP1A1*2C AG genotype was associated with a significantly decreased risk of male infertility [odds ratio (OR) = 0.56, 95% confidence interval (95% CI) = 0.36-0.86, p = 0.005] compared with the AA genotype. A statistically significantly decreased risk of male infertility was found to be associated with the CYP1A1*2C AG genotype plus GG genotype compared with CYP1A1*2C AA genotype (OR = 0.60, 95% CI = 0.40-0.91, p = 0.011). No significant association was detected between CYP1A1*2A polymorphism and male infertility. Haplotypic analysis showed a significantly increased risk of male infertility associated with the C-A haplotype compared with the T-A haplotype (OR = 1.98, 95% CI = 1.27-3.09), indicating a synergic effect of the two polymorphisms. Our results suggest that the CYP1A1 polymorphisms may contribute to the pathogenesis of male infertility in the Han-Chinese population.

Reciprocal translocation t(7;16)(q21.2;p13.3) in an infertile man

OBJECTIVE

To report the first case of reciprocal translocation t(7;16)(q21.2;p13.3) associated with male factor infertility.

DESIGN

Case report.

SETTING

University genetics laboratory and university andrology unit.

PATIENT(S)

A 38-year-old man with infertility and oligoasthenoteratozoospermia, but otherwise healthy.

INTERVENTION(S)

Chromosome analyses from peripheral blood lymphocyte cultures using Giemsa (G)-banding (GTG) and C-banding (CBG) and fluorescent in situ hybridization (FISH) were performed.

MAIN OUTCOME MEASURE(S)

Sperm count, motility, morphology, GTG and CBG banding, and FISH.

RESULT(S)

We report an apparently unique reciprocal translocation t(7;16)(q21.2;p13.3) confirmed by FISH in an infertile man. Semen analyses showed oligoasthenoteratozoospermia, with sperm count ranging from 2 x 10(6)/mL to 5 x 10(6)/mL and head defects (98%) in sperm morphology.

CONCLUSION(S)

In the present patient the breakpoint at 16p13.3 could have disrupted or harbored the PRM1, PRM2, or TNP2 genes responsible for the replacement of the histones involved in packaging the DNA into the sperm head. Resulting haploinsufficiency of these genes is likely to be the cause of sperm head defects and infertility in the patient. This case supports the opinion that alterations in the expression of protamine genes may be one of the causes of male factor infertility.

Cytochrome P-450 1A1 gene polymorphisms and risk of breast cancer: a HuGE review

Cytochrome P-450 (CYP) 1A1 plays a key role in phase I metabolism of polycyclic aromatic hydrocarbons and in estrogen metabolism. It is expressed predominantly in extrahepatic tissues, including the breast. Four CYP1A1 gene polymorphisms (3801T --> C, Ile462Val, 3205T --> C, and Thr461Asp) have been studied in relation to breast cancer. The 3801C variant is more common than the Val variant. Both variants occur more frequently in Asians than in White populations. The 3205T --> C polymorphism has been observed in African Americans only. Little data are available on the geographic/ethnic distribution of the Thr461Asp polymorphism. The functional significance of the polymorphisms is unclear. In 17 studies, no consistent association between breast cancer and CYP1A1 genotype was found. Meta-analysis found no significant risk for the genotypes 1) 3801C/C (relative risk (RR) = 0.97, 95% confidence interval (CI): 0.52, 1.80) or 3801T/C (RR = 0.91, 95% CI: 0.70, 1.19) versus 3801T/T, 2) Val/Val (RR = 1.04, 95% CI: 0.63, 1.74) or Ile/Val (RR = 0.92, 95% CI: 0.76, 1.10) versus Ile/Ile, or 3) Asp/Asp (RR = 0.95, 95% CI: 0.20, 4.49) or Thr/Asp (RR = 1.12, 95% CI: 0.87, 1.43) versus Thr/Thr. Future studies should explore possible interactions between CYP1A1 and sources of polycyclic aromatic hydrocarbons, markers of estrogen exposure, other lifestyle factors influencing hormonal levels, and other genes involved in polycyclic aromatic hydrocarbon metabolism or hormonal biosynthesis.

DAZL polymorphisms and susceptibility to spermatogenic failure: an example of remarkable ethnic differences

Polymorphisms in genes involved in spermatogenesis are considered potential risk factors for male infertility. Recently a polymorphism in the deleted in azoospermia-like (DAZL) gene (T54A) was reported as susceptibility factor to oligo/azoospermia in the Chinese population. DAZL is an autosomal homologue of the Y chromosomal DAZ (deleted in azoospermia) gene cluster and both are considered master regulators of spermatogenesis. The aim of the present study was to screen (i) for mutations of the entire coding sequence of the DAZL gene in patients lacking of the DAZ gene cluster, in order to evaluate if DAZL polymorphisms may influence the AZFc deletion phenotype; (ii) for the two previously described (and eventually newly identified) single nucleotide polymorphisms (SNPs) in a large group of infertile and normospermic men of Italian origin. We failed to detect new mutations. We confirmed previous results showing no evidence for a functional role of the T12A mutation. Surprisingly, the T54A polymorphism, which was present in 7.4% of the Chinese patients was absent in our Caucasian population. This remarkable difference represent an example of how ethnic background is important also for polymorphisms involved in spermatogenesis and contributes to better select clinically relevant tests, specifically based on the ethnic origin of the infertile patients.

Cytochrome P4501A1 polymorphisms in a Caucasian population with porphyria cutanea tarda

Porphyria cutanea tarda (PCT) is the most frequent porphyria in humans. The familial type is in contrast to the sporadic type due to an inherited defect of the uroporphyrinogen-II-decarboxylase (URO-D) and both types need additional porphyrinogens to lead to the clinical manifestation of the disease. Various factors such as xenobiotics (i.e. polycyclic aromatic hydrocarbons), alcohol, hormones and viral liver infections (hepatitis B and C) are known to induce porphyria. Cytochrome p450 enzymes play a crucial role in the metabolism of porphyrogens and therefore might have an important influence on the pathogenesis of hepatic porphyrias. Association of CYP1A2 polymorphisms with susceptibility to both types of PCT has already been described in Danish patients. We investigated 65 caucasian patients with PCT in comparison to a healthy control group concerning the tpe of PCT and the cytochrome p4501A1 polymorphisms (m1, m2 and m4) using polymerase chain reaction (PCR) and a restriction fragment length polymorphism. We found an increased incidence of the m4 polymorphism in the familial type of PCT (odds ratio 5.5, P-value 0.01), whereas the m1 and m2 mutations, might be provoked by a higher susceptibility to porphyrogens via the cytochrome p4501A1 m4 polymorphism.

Relationship between Y-chromosomal DNA haplotype and sperm count in Italy

Forty Italian individuals with sperm counts in the range 20-130x10(6)/ml were typed with eleven Y-specific binary markers. Five Y haplogroups (1, 2, 3, 9 and 21) were present in the sample. In Italy, in contrast to Denmark, sperm counts were similar in the different haplogroups.

Polymorphisms of glutathione S-transferase M1 and male infertility in Taiwanese patients with varicocele

BACKGROUND

To examine glutathione S-transferase M1 (GST M1) gene polymorphism and male infertility in Taiwanese patients with varicocele, 80 young male patients with varicocele (group 1), 62 young male patients with subclinical varicocele (group 2) and 60 normal young males (group 3) were recruited in this study.

METHODS

GST M1 null homozygous genotype [GST M1-] and the occurrence of a 4977 bp deletion of sperm mitochondrial DNA (mtDNA) were determined by polymerase chain reaction. The 8-hydroxy-2'-deoxyguanosine (8-OHdG) content of sperm DNA was measured by high-performance liquid chromatography.

RESULTS

The frequencies of GST M1- genotype were 43.8, 41.9 and 45% for patients in groups 1, 2 and 3 respectively. In group 1 patients with GST M1- genotype, the frequency of the presence of the 4977 bp deletion in sperm mtDNA (54.3%) was significantly higher than that of the patients without the 4977 bp deletion in sperm mtDNA (45.7%, OR: 2.63, P = 0.04). Patients of groups 1 and 2 with GST M1- genotype had significantly higher 8-OHdG content in sperm DNA and lower protein thiols and ascorbic acid in seminal plasma than those with GST M1+ genotype.

CONCLUSION

GST M1- genotype predisposes to increased oxidative damage to sperm of patients with varicocele.

Xenobiotic metabolism, genetic polymorphisms and male infertility

Male reproductive function may be impaired by various occupational and environmental chemical agents. The majority of these xenobiotics, however, require metabolic activation in order to exert adverse effects via covalent interactions between intermediate metabolites and cellular macromolecules such as DNA or protein. In addition, metabolization may alter endocrine-disrupting properties of xenobiotics. Thus tissue-specific expression and regulation of multiple xenobiotic-metabolizing enzymes are likely to play an important role in chemically induced disorders of male reproductive organs. Recent studies suggest that genetic polymorphisms underlying inter-individual and inter-ethnic variability of xenobiotic metabolism modulate susceptibility to male reproductive disorders. For cytochrome P450 1A1 (CYP1A1), a key enzyme in extra-hepatic metabolic activation of lipophilic xenobiotics, increased frequencies of two genetically linked polymorphisms have been found among infertile men.