https://apps.who.int/iris/bitstream/10665/78102/1/WHO_HSE_PHE_IHE_2013.1_eng.pdf

State of the Science of Endocrine Disrupting Chemicals - 2012

Reproduction is required for the survival of all mammalian species, and thousands of essential 'sex' genes are conserved through evolution. Basic research helps to define these genes and the mechanisms responsible for the development, function and regulation of the male and female reproductive systems. However, many infertile couples continue to be labeled with the diagnosis of idiopathic infertility or given descriptive diagnoses that do not provide a cause for their defect. For other individuals with a known etiology, effective cures are lacking, although their infertility is often bypassed with assisted reproductive technologies (ART), some accompanied by safety or ethical concerns. Certainly, progress in the field of reproduction has been realized in the twenty-first century with advances in the understanding of the regulation of fertility, with the production of over 400 mutant mouse models with a reproductive phenotype and with the promise of regenerative gonadal stem cells. Indeed, the past six years have witnessed a virtual explosion in the identification of gene mutations or polymorphisms that cause or are linked to human infertility. Translation of these findings to the clinic remains slow, however, as do new methods to diagnose and treat infertile couples. Additionally, new approaches to contraception remain elusive. Nevertheless, the basic and clinical advances in the understanding of the molecular controls of reproduction are impressive and will ultimately improve patient care.

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The biology of infertility: research advances and clinical challenges

Background Chronic mucocutaneous candidiasis may be manifested as a primary immunodeficiency characterized by persistent or recurrent infections of the mucosa or the skin with candida species. Most cases are sporadic, but both autosomal dominant inheritance and autosomal recessive inheritance have been described. Methods We performed genetic studies in 36 members of a large, consanguineous five-generation family, in which 4 members had recurrent fungal infections and an additional 3 members died during adolescence, 2 after invasive infection of the brain with candida species. All 36 family members were enrolled in the study, and 22 had blood samples taken for DNA analysis. Homozygosity mapping was used to locate the mutated gene. In the 4 affected family members (patients) and the 18 unaffected members we sequenced CARD9, the gene encoding the caspase recruitment domaincontaining protein 9, carried out T-cell phenotyping, and performed functional studies, with the use of either leukocytes from the patients or a reconstituted murine model of the genetic defect.

/pdf/a-homozygous-card9-mutation-in-a-family-with-susceptibility-1wn0idbxq2.pdf

A Homozygous CARD9 Mutation in a Family with Susceptibility to Fungal Infections

https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(12)60071-3.pdf

Androgen insensitivity syndrome

Two cases of Noonan syndrome are observed. The Noonan syndrome is a Turner-like syndrome with normal chromosomal constitution. Essential criteria in diagnosing the syndrome are the facial expression (hyper-telorisme, low-set and malformed ears, micrognathie, fish-like mouth). The short webbed neck and the cubitus valgus. These children are rather small and mental retardation can be present, especially in comparison with their siblings. Associated cardiac malformations occur in approximately 50% of the cases. We insist on audiologic findings. One case has a hearing impairment due to a malformation of the middle ear, recognised radiologically. The other has a deafness of perception type. Yet, the familial occurrence of last patient makes it doubtful whether this hearing loss can be linked to the Noonan-syndrome.

The Noonan syndrome

Male infertility represents one of the clearest examples of a complex disease with a substantial genetic basis. Numerous male mouse models, mutation screening and association studies reported over the last few years reveal the high prevalence of genetic causes of spermatogenic impairment, accounting for 10-15% of severe male infertility, including chromosomal aberrations and single gene mutations. Natural selection prevents the transmission of mutations causing infertility, but this protective mechanism may be overcome by assisted reproduction techniques. Consequently, the identification of genetic factors is important for appropriate management of the infertile couple. However, a large proportion of infertile males are diagnosed as idiopathic, reflecting poor understanding of the basic mechanisms regulating spermatogenesis and sperm function. Furthermore, the molecular mechanisms underlying spermatogenic damage in cases of genetic infertility (for example Yq microdeletions) are not known. These problems can be addressed only by large scale association studies and testicular or spermatozoal expression studies in well-defined alterations of spermatogenesis. It is conceivable that these studies will have important diagnostic and therapeutic implications in the future. This review discusses the genetic causes of male infertility known to date, the genetic polymorphisms possibly associated with male infertility, and reports novel results of global gene expression profiling of normal human testis by microarray technology.

https://www.rbmojournal.com/article/S1472-6483(10)60677-3/pdf

Male infertility: role of genetic background

Cryptorchidism is the most frequent congenital birth defect in male children (2-4% in full-term male births), and it has the potential to impact the health of the human male. In fact, although it is often considered a mild malformation, it represents the best-characterized risk factor for reduced fertility and testicular cancer. Furthermore, some reports have highlighted a significant increase in the prevalence of cryptorchidism over the last few decades. Etiology of cryptorchidism remains for the most part unknown, and cryptorchidism itself might be considered a complex disease. Major regulators of testicular descent from intraabdominal location into the bottom of the scrotum are the Leydig-cell-derived hormones testosterone and insulin-like factor 3. Research on possible genetic causes of cryptorchidism has increased recently. Abundant animal evidence supports a genetic cause, whereas the genetic contribution to human cryptorchidism is being elucidated only recently. Mutations in the gene for insulin-like factor 3 and its receptor and in the androgen receptor gene have been recognized as causes of cryptorchidism in some cases, but some chromosomal alterations, above all the Klinefelter syndrome, are also frequently involved. Environmental factors acting as endocrine disruptors of testicular descent might also contribute to the etiology of cryptorchidism and its increased incidence in recent years. Furthermore, polymorphisms in different genes have recently been investigated as contributing risk factors for cryptorchidism, alone or by influencing susceptibility to endocrine disruptors. Obviously, the interaction of environmental and genetic factors is fundamental, and many aspects have been clarified only recently.

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Role of Hormones, Genes, and Environment in Human Cryptorchidism

Summary Objective Androgens and a functioning androgen receptor (AR) are essential for development and maintenance of the male phenotype and spermatogenesis. Consistent with this, mutations in the AR gene cause a variety of defects related to androgen insensitivity, ranging from complete feminization to phenotypic males with infertility. The aim of his study was to analyse the prevalence of AR gene mutations in male infertility and to clarify the genotype-phenotype relation. Design Males with infertility were recruited consecutively at the Centre for Male Gamete Cryopreservation at the University of Padova from January 1996 to January 2005. Patients One thousand five hundred and seventeen men with < 10 million sperm/ml and 310 age-matched normozoospermic controls. Methods Screening for AR gene mutation was done by DHPLC and sequencing, and reproductive hormone concentrations were measured. Results We found 20 mutations in 26 of 1517 patients (1·7%) and no mutations in controls. A high number of mutations localized in exon 1 of the AR gene coding for the transactivation domain of the protein. Of 20 mutations, 7 represent novel mutations. With respect to men without AR mutations, subjects with AR mutations have lower ejaculate volume, higher testosterone levels, higher oestradiol levels, and higher androgen sensitivity index. However, the ranges for these variables were highly overlapping between men with and without AR gene mutations. Also clinical manifestations of AR mutations are not unique and 22 men had only spermatogenic impairment. Conclusions AR gene mutations are quite frequent in unselected infertile men but no specific hormonal or clinical data could be used to preselect patients at risk of mutations.

Male infertility and androgen receptor gene mutations: clinical features and identification of seven novel mutations

Context Cryptorchidism is the most frequent congenital birth defect in male children and represents an important risk factor for infertility and testicular cancer. Major regulators of testicular descent are the hormones insulin-like factor 3 (INSL3) and testosterone, and disruption of these pathways might cause cryptorchidism. Objective To determine the frequency of genetic alterations in cryptorchidism. Design and Setting Case-control study in 2 departments of pediatric surgery in Italy between January 2003 and March 2005. Patients Six hundred male infants with cryptorchidism. Boys were followed up for 2 to 3 years (through January 2008) and orchidopexy was performed in those who were persistently cryptorchid. We analyzed 300 noncryptorchid male children aged 1 to 4 years as controls. Main Outcome Measures Karyotype anomalies and INSL3, INSL3 receptor, and androgen receptor gene mutations. Results The frequency of genetic alterations in boys with cryptorchidism was low (17/600 [2.8%; 95% confidence interval {CI}, 1.7%-4.5%]) and was significantly higher in participants with persistent cryptorchidism (16/303 [5.3%; 95% CI, 3.0%-8.4%]; P = .001) and those with bilateral cryptorchidism (10/120 [8.3%; 95% CI, 4.1%-14.8%]; P = .001) than in controls (1/300 [0.3%; 95% CI, 0.1%-0.8%]). Boys with persistent cryptorchidism had a 17-fold greater odds of having a genetic alteration (odds ratio, 16.7; 95% CI, 2.2-126.5). The most common genetic findings in those with cryptorchidism were 8 cases of Klinefelter syndrome and 5 cases of mutations in the INSL3 receptor gene. Genetic alterations were not found in boys with low birth weight or low gestational age, who had frequent spontaneous descent of the testes. Conclusion In a small percentage of the study population, there was a statistically significant association between bilateral and persistent cryptorchidism and genetic alterations, including Klinefelter syndrome and INSL3 receptor gene mutations.

https://jamanetwork.com/journals/jama/articlepdf/182919/joc80111_2271_2276.pdf

Genetic Alterations Associated With Cryptorchidism

https://www.fertstert.org/article/S0015-0282(08)04408-7/pdf

Daniela Zuccarello

Papers

Male infertility: role of genetic background

Role of Hormones, Genes, and Environment in Human Cryptorchidism

Male infertility and androgen receptor gene mutations: clinical features and identification of seven novel mutations

Genetic Alterations Associated With Cryptorchidism

Human papillomavirus found in sperm head of young adult males affects the progressive motility