Molecular evaluation of CFTR sequence variants in male infertility of testicular origin

Although the involvement of the CFTR gene has been well established in congenital agenesia of vas deferens, its role in non-obstructive (NOb) infertility is still a matter of debate. In order to definitively define the involvement of the CFTR gene in spermatogenic impairment and a potential synergistic contribution to known genetic and clinical factors, genetic variants in the entire coding sequence and the immediately flanking regions of the CFTR gene, along with a thorough clinical evaluation, were analysed in 83 NOb infertile patients and 87 clinically well-defined fertile individuals as controls. The results of our study showed no statistical difference between CFTR carrier frequency in the infertile and fertile population. Specifically, the IVS8-6(5T) allele carrier frequency was similar in NOb infertile patients when compared with fertile men, but it is noteworthy that, when fertile men were classified into having optimal and suboptimal fertility, no 5T allele was found among the 35 men with optimal fertility parameters. In conclusion, extensive CFTR analysis in infertile individuals and fertile population as adequate control definitively excludes the involvement of the CFTR gene variants in sperm production and stresses the importance of carefully identifying those individuals with obstructive defects, in whom CFTR screening will be beneficial.     

Diagnosis of male infertility

A detailed medical history and clinical examination are important steps in the diagnosis of male infertility. Tests include semen analysis according to WHO standards, laboratory tests (mainly determination of follicle-stimulating hormone) and scrotal sonography. Invasive diagnostic procedures, such as testicular biopsy or investigation of seminal pathway obstruction, are generally combined with therapeutic sperm retrieval for cryopreservation or microsurgical refertilization.     

Assessment of male infertility

The diagnosis of male infertility requires methodical approach which is primarily clinical, aimed at identifying all potential factors. Biological and radiological assessments allow diagnosis confirmation, and evaluation of both prognosis and therapeutic strategy.     

Genetics of male infertility

Genetic causes of male infertility increase in frequency with decreasing sperm concentration (oligo-/azoospermia). The decision about genetic tests should be made after a complete andrological work-up. Common causes comprise chromosomal aberrations (including Klinefelter syndrome), microdeletions of the AZF loci of the Y chromosome, mutations in the gene responsible for cystic fibrosis (CFTR) causing CBAVD and in genes involved in hypogonadotropic hypogonadism (including Kallmann syndrome). Every genetic investigation should be accompanied by comprehensive genetic counselling to help with the interpretation of results and support the patient/the couple concerning consequences for their family planning and treatment options.     

Beta-endorphin and male infertility

Beta-endorphin (beta-ED) levels were evaluated in blood and seminal plasma of men with infertility due to varicocele, obstructive and nonobstructive azoospermia, and idiopathic oligoasthenospermia. The relation of this opiate to serum levels of gonadotropins, prolactin, testosterone, androstenedione, and dehydroepiandrosterone sulfate has also been investigated. beta-ED levels in seminal plasma were significantly higher than in blood plasma (p less than 0.001) in all persons studied. No statistically significant differences were found for beta-ED concentrations in semen or blood among any of the infertility situations studied. Nor were significant correlations observed between the concentration of this opiate and that of gonadotropins, prolactin, and androgens. The measurement of beta-ED in semen has little value in the differential diagnosis of male infertility. Nonetheless, its presence in high levels in semen must have some unknown function. Possibly, it comes from the various sites of the male reproductive tract, since no significant differences were found between obstructive and nonobstructive azoospermias.     

Sulphasalazine-induced reversible male infertility

A male patient suffering from ulcerative colitis, presented with primary infertility due to sulphasalazine therapy. Sulphasalazine was discontinued and the patient was treated with a 5-aminosalicylic acid preparation (Salofalk) in the form of an enema. After 3 months, the semen quality was dramatically improved and a successful pregnancy ensued. The sulphapyridine moiety of sulphasalazine seems to be responsible for male infertility and depressed semen quality. The metabolite 5-aminosalicylic acid is proposed as a suitable alternative to sulphasalazine in cases of male infertility.     

精索静脉曲张与男性不育

精索静脉曲张(VC)是导致男性不育的最常见原因之一,手术是治疗VC的主要方法。近来,关于VC导致不育的病理机制研究较多,尤其是细胞分子机制的研究进展较快,主要包括生精细胞凋亡异常和氧化应激。同时,对于VC手术指征和各种术式优劣性的认识也渐趋统一。本文介绍VC导致不育的细胞分子机制及临床治疗决策的研究进展。     

Lycopene and male infertility

Excessive amounts of reactive oxygen species （ROS） cause a state of oxidative stress, which result in sperm membrane lipid peroxidation, DNA damage and apoptosis, leading to decreased sperm viability and motility. Elevated levels of ROS are a major cause of idiopathic male factor infertility, which is an increasingly common problem today. Lycopene, the most potent singlet oxygen quencher of all carotenoids, is a possible treatment option for male infertility because of its antioxidant properties. By reacting with and neutralizing free radicals, lycopene could reduce the incidence of oxidative stress and thus, lessen the damage that would otherwise be inflicted on spermatozoa. It is postulated that lycopene may have other beneficial effects via nonoxidative mechanisms in the testis, such as gap junction communication, modulation of gene expression, regulation of the cell cycle and immunoenhancement. Various lycopene supplementation studies conducted on both humans and animals have shown promising results in alleviating male infertility--lipid peroxidation and DNA damage were decreased, while sperm count and viability, and general immunity were increased. Improvement of these parameters indicates a reduction in oxidative stress, and thus the spermatozoa is less vulnerable to oxidative damage, which increases the chances of a normal sperm fertilizing the egg. Human trials have reported improvement in sperm parameters and pregnancy rates with supplementation of 4-8 mg of lycopene daily for 3-12 months. However, further detailed and extensive research is still required to determine the dosage and the usefulness of lycopene as a treatment for male infertility.     

Genetic evaluation of male infertility

Men with severe oligospermia (<5 million sperm/mL ejaculate fluid) or azoospermia should receive genetic testing to clarify etiology of male infertility prior to treatment. Categorization by obstructive azoospermia (OA) or non-obstructive azoospermia (NOA) is critical since genetic testing differs for the former with normal testicular function, testicular volume (~20 mL), and follicle-stimulating hormone (FSH) (1-8 IU/mL) when compared to the latter with small, soft testes and increased FSH. History and physician examination along with laboratory testing (following appropriate genetic counseling) is critical to accurate selection of genetic testing appropriate for azoospermia due to primary testicular failure as compared with congenital hypogonadotropic hypogonadism (HH). Genetic testing options include cystic fibrosis transmembrane conductance regulator (CFTR) testing for men with congenital absence of the vas, while karyotype, Y chromosome microdeletions (YCMD), and other specific genetic tests may be warranted depending on the clinical context of severe oligospermia or NOA. The results of genetic testing guide management options. The most recent techniques for genetic analysis, including sperm microRNA (miRNA) and epigenetics, are forming the foundation for future genetic diagnosis and therapeutic targets in male infertility.     

Endocrine causes of male infertility

Although endocrinopathies are not often seen in infertile men, these disorders are clinically significant; they often have potentially serious medical significance, regardless of fertility issues. Correction of these disorders represents a possible way to restore normal fertility for the male partner. Male fertility is critically dependent upon a normal hormonal milieu. The hypothalamic-pituitary-gonadal axis is quite sensitive to disruption by endocrine disorders and other generalized medical disorders. Thus, male infertility is occasionally the presenting sign for significant underlying medical disease; it is important to properly evaluate these patients.     

Genetic causes of male infertility

Summary.  Male infertility has often been ascribed to infections, immunologic factors, chemical insults or malformations. About 10% of infertile males have severe defects in sperm production. Lately, research has focused on possible genetic aetiologies. In this review genetic causes of male infertility are discussed. For pragmatic reasons three groups have been defined. In the first group, disorders of sexual differentiation associated with male infertility are considered. In the second group, male infertility is discussed in a context of some genetic diseases. In the third group, genetic causes for isolated defects of sperm production and function are reported.     

Microsurgical management of male infertility

The introduction of microsurgical techniques has revolutionized the treatment of male infertility. As a result of technical advances and innovation over the past 10-15 years, previously infertile couples are now able to conceive naturally or to parent their own biological children with the aid of assisted reproductive technologies. This article reviews the indications, techniques, and outcomes of the various microsurgical procedures currently used to optimize male fertility. The most up-to-date methods of microsurgical vasal and epididymal reconstruction, sperm retrieval, and varicocele repair are discussed.     

Diagnosis of male infertility]

The diagnostic methods for male infertility in our clinic are reviewed, and the following are emphasized. In azoospermia, examinations for obstructive azoospermia such as testicular biopsy should be made focussing on patients with 10 ml or higher testicular volume and with 20 mIU/ml or lower serum FSH level. In hypospermic patients, examination of post-ejaculated urine and ultrasonotomography examination of prostate are necessary for the diagnosis of incomplete retrograde ejaculation and obstruction or stenosis of the ejaculatory ducts.     

Medical treatment of male infertility

The majority of male infertility is idiopathic. However, there are multiple known causes of male infertility, and some of these causes can be treated medically with high success rates. In cases of idiopathic or genetic causes of male infertility, medical management is typically empirical; in most instances medical therapy represents off-label use that is not specifically approved by the FDA. Understanding the hypothalamic-pituitary-gonadal (HPG) axis and the effect of estrogen excess is critical for the assessment and treatment of male infertility. The use of certain medical treatment has been associated with an increase in sperm production or motility, and primarily focuses on optimizing testosterone (T) production from the Leydig cells, increasing follicle-stimulating hormone (FSH) levels to stimulate Sertoli cells and spermatogenesis, and normalizing the T to estrogen ratio.     

Genetic aspects of male infertility

Cytogenetic analyses performed in infertile men showed a frequency of genetic abnormalities definitely higher than in normal population. Cytogenetic analysis is perfectly justified in infertile men with normal phenotype.     

Clinical study of male infertility

A statistical analysis was performed on infertile male patients who visited our urological clinic between Jan. 1976 and Dec. 1981. The incidence of infertile male was 9.9% of the total male out-patients. Age distribution of most of the patients ranged from 25 to 34 years old. Infertile period was most commonly within 5 years after they had married. In semen analysis, the cases of azoospermia and oligozoospermia (less than 50 x 10(6)/ml) accounted for 80% of all the infertile males. Testicular histology showed hypospermatogenesis or "Sertoli cell only" in most patients (more than 84.2%) who received testicular biopsy. Decrease in testicular volume was accompanied by an increase in the serum levels of luteinizing hormone and follicle stimulating hormone, but there was no relationship between testicular volume and testosterone. Most of the patients with a testicular volume of less than 12 ml were azoospermic. This suggests that there may be a suppression of spermatogenesis in small testes.     

Medical treatment of male infertility

After an appropriate clinical and laboratory assessment of a patient's fertility status, the clinician must often decide whether specific and empiric treatment is indicated. Specific treatment may take the form of replacement therapy (exogenous gonadotropins or GnRH) for pituitary or hypothalamic failure, inhibition of prolactin secretion, antimicrobial therapy, or immunosuppressive therapy for demonstrable immunologic infertility. Finally, ejaculatory dysfunction often requires sympathomimetic agents. Alternatively, in the normogonadotropic oligospermic patient, the major form of empiric therapy relies on the enhancement of physiologic hormone levels that influence spermatogenesis. Such "stimulation" therapy may be achieved by GnRH analogues, antiestrogens, exogenous gonadotropins, or androgens.     

Preventable causes of male infertility

Summary The initial evaluation of the infertile man includes a diligent search for testicular factors, gonadotoxins, and coital factors so as to identify existing causes of impaired fertility and to prevent further dimunition in fertility. There are also prophylactic measures in the treatment of all men that can prevent future infertility, such as prompt correction of cryptorchidism, testicular torsion, genital infection, and adolescent varicocele and proper precautions to limit occupational, medical, and recreational gonadotoxins.