Y chromosome microdeletions in infertile men: prevalence, phenotypes and screening markers for the Indian population

Clinical Analysis of Y Chromosome Microdeletions and Chromosomal Aberrations in 1596 Male Infertility Patients of the Zhuang Ethnic Group in Guangxi

The long arm of the Y chromosome (Yq) contains many amplified and palindromic sequences that are prone to self-reorganization during spermatogenesis, and tiny submicroscopic segmental deletions in the proximal Yq are called Y chromosome microdeletions (YCM). A retrospective study was conducted on male infertility patients of Zhuang ethnicity who presented at Reproductive Medical Center of Nanning between January 2015 and May 2023. Seminal fluid was collected for standard examination. YCM were detected by using a combination of multiplex PCR and agarose gel electrophoresis. Preparation of peripheral blood chromosomes and karyotyping of chromosomes was performed. 147 cases (9.22%) of YCM were detected in 1596 male infertility patients of Zhuang ethnicity. Significant difference was found in the detection rate of YCM between the azoospermia group and the oligospermia group (P < 0.001). Of all types of YCM, the highest detection rate was AZFc (n = 83), followed by AZFb + c (n = 28). 264 cases (16.54%) of sex chromosomal aberrations were detected. The most prevalent karyotype was 47, XXY (n = 202). The detection rate of sex chromosomal aberrations in azoospermia group was higher than that in severe oligospermia group and oligospermia group, and the differences were significant (P < 0.001). 28 cases (1.57%) of autosomal aberrations and 105 cases (6.58%) of chromosomal polymorphism were identified. The current research has some limitations due to the lack of normal men as the control group but suggests that YCM and chromosomal aberrations represent key genetic factors influencing spermatogenesis in infertile males of Zhuang ethnicity in Guangxi.

Y chromosome microdeletions in Chinese men with infertility: prevalence, phenotypes, and intracytoplasmic sperm injection outcomes

BACKGROUND

The incidence of Y chromosome microdeletions varies among men with infertility across regions and ethnicities worldwide. However, comprehensive epidemiological studies on Y chromosome microdeletions in Chinese men with infertility are lacking. We aimed to investigate Y chromosome microdeletions prevalence among Chinese men with infertility and its correlation with intracytoplasmic sperm injection (ICSI) outcomes.

METHODS

This single-center retrospective study included 4,714 men with infertility who were evaluated at the Reproductive Center of the First Affiliated Hospital of Sun Yat-sen University between May 2017 and January 2021. Semen analysis and Y-chromosome microdeletion via multiplex polymerase chain reaction were conducted on the men. The study compared outcomes of 36 ICSI cycles from couples with male azoospermia factor (AZF)cd deletions with those of a control group, which included 72 ICSI cycles from couples without male Y chromosome microdeletions, during the same period. Both groups underwent ICSI treatment using ejaculated sperm.

RESULTS

Among 4,714 Chinese men with infertility, 3.31% had Y chromosome microdeletions. The combined deletion of sY254 and sY255 in the AZFc region and sY152 in the AZFd region was the prevalent pattern of Y chromosome microdeletion, with 3.05% detection rate. The detection rates of AZF deletions in patients with normal total sperm count, mild oligozoospermia, severe oligozoospermia, cryptozoospermia, and azoospermia were 0.17%, 1.13%, 5.53%, 71.43%, and 7.54%, respectively. Compared with the control group, the AZFcd deletion group exhibited no significant difference in the laboratory results or pregnancy outcomes of ICSI cycles using ejaculated sperm.

CONCLUSIONS

This is the largest epidemiological study on Y chromosome microdeletions in Chinese men with infertility. The study results underline the necessity for detecting Y chromosome microdeletion in men with infertility and severe sperm count abnormalities, especially those with cryptozoospermia. The combined deletion of sY254 and sY255 in the AZFc region and sY152 in the AZFd region was the most prevalent Y chromosome microdeletion pattern. Among patients with AZFcd deletion and ejaculated sperm, ICSI treatment can result in pregnancy outcomes, similar to those without AZFcd deletion.

First report of frequencies of Y chromosome microdeletions at a reproductive medicine center in Peru

Objective

Y chromosome Microdeletions are the second genetic cause of infertility in men. Despite its importance for infertility treatment, there is no previous research in Peru. The aim of this study was to determine the frequencies and characteristics of Y chromosome microdeletions in a group of men who sought infertility consultation at a specialized reproductive medicine center in Peru.

Methods

In this study, 201 semen samples were analyzed. The samples were obtained from Niu Vida's fertility program. Each seminal sample was analyzed according to the recommendations of the Laboratory Manual of the World Health Organization (WHO) 2010. A buccal swab and a 500 μL aliquot of seminal sample were used for the molecular study of Y chromosome microdeletions in each patient. The frequencies and the type of Y chromosome microdeletion in the AZFa, AZFb and AZFc regions were evaluated.

Results

The prevalence of Y chromosome microdeletions in the AZF region was 6.45% in oligozoospermic and azoospermic patients, and a prevalence of 20% was observed specifically in azoospermic patients. No microdeletions of AZFb type were detected. A partial region microdeletion of AZFa was detected in a teratozoospermic patient with a normal sperm count.

Conclusions

The study represents the first report on the incidence of Y chromosome microdeletions in Peru. Our results indicate a high prevalence of microdeletions in azoospermic patients compared to similar studies. It is suggested to assess the presence of AZFa microdeletions and to evaluate additional genetic markers in this region to identify specific mutations that may cause impaired sperm production and male infertility in the Peruvian male population.

The significance of karyotyping and azoospermia factor analysis in patients with nonobstructive azoospermia or oligozoospermia

OBJECTIVE

We present our study about the significance of karyotyping and azoospermia factor(AZF) analysis in patients with azoospermia or oligozoospermia.

MATERIALS AND METHODS

We retrospectively reviewed 141 Taiwanese patients with nonobstructive azoospermia and 45 Taiwanese patients with oligozoospermia at MacKay Memorial Hospital, Taiwan, from 2010 to 2021 to determine the significance of karyotyping and azoospermia factor analysis. The karyotyping was analyzed using the Giemsa banding method. The AZF microdeletions were determined using multiplex polymerase chain reaction using primers specifically flanking the AZF subregions.

RESULTS

We found that 7.80% of patients with nonobstructive azoospermia had AZF microdeletions and 19.86% of patients with nonobstructive azoospermia had chromosomal anomalies or polymorphic variations. Furthermore, 4.44% of patients with oligozoospermia had AZF microdeletions, and 4.44% of patients with oligozoospermia had chromosomal anomalies or polymorphic variations.

CONCLUSION

In this study, 25.53% of patients with nonobstructive azoospermia and 8.88% of patients with oligozoospermia had abnormal findings. The significance of karyotyping and azoospermia factor analysis is more critical in patients with nonobstructive azoospermia than patients with oligozoospermia. Both karyotyping and AZF analysis could prevent delayed treatment for male infertility through accurate diagnosis and appropriate treatment. The number of our patients with AZFc microdeletion was also higher than that of patients with AZFa or AZFb. The spermatogenic potential may gradually decline in patients with AZFc microdeletion. The earlier is the diagnosis, the earlier will be the retrieval of testicular spermatozoa.

Repetitive DNA Sequences in the Human Y Chromosome and Male Infertility

The male-specific Y chromosome, which is well known for its diverse and complex repetitive sequences, has different sizes, genome structures, contents and evolutionary trajectories from other chromosomes and is of great significance for testis development and function. The large number of repetitive sequences and palindrome structure of the Y chromosome play an important role in maintaining the stability of male sex determining genes, although they can also cause non-allelic homologous recombination within the chromosome. Deletion of certain Y chromosome sequences will lead to spermatogenesis disorders and male infertility. And Y chromosome genes are also involved in the occurrence of reproductive system cancers and can increase the susceptibility of other tumors. In addition, the Y chromosome has very special value in the personal identification and parentage testing of male-related cases in forensic medicine because of its unique paternal genetic characteristics. In view of the extremely high frequency and complexity of gene rearrangements and the limitations of sequencing technology, the analysis of Y chromosome sequences and the study of Y-gene function still have many unsolved problems. This article will introduce the structure and repetitive sequence of the Y chromosome, summarize the correlation between Y chromosome various sequence deletions and male infertility for understanding the repetitive sequence of Y chromosome more systematically, in order to provide research motivation for further explore of the molecules mechanism of Y-deletion and male infertility and theoretical foundations for the transformation of basic research into applications in clinical medicine and forensic medicine.

Prevalence of Y chromosome microdeletion in azoospermia factor subregions among infertile men from West Bengal, India

Background

Etiology of male infertility is intriguing and Y chromosome microdeletion within azoospermia factor (AZF) sub‐regions is considered major cause. We conducted a screening for Y chromosome microdeletion in an infertile male cohort from West Bengal, India to characterize Y chromosome microdeletion among infertile men.

Methods

We recruited case subjects that were categorized on the basis of sperm count as azoospermia (N = 63), severe oligozoospermia (N = 38), and oligozoospermia (N = 17) and compared them with age, demography, and ethnicity matched healthy proven fertile control males (N = 84). Sequence Tagged Site makers and polymerase chain reaction based profiling of Y chromosome was done for AZF region and SRY for cases and controls.

Results

We scored 16.1% of cases (19 out of 118) that bear one or more microdeletions in the studied loci and none among the controls. The aberrations were more frequent among azoospermic males (17 of 19) than in severe oligozoospermic subjects (2 of 19).

Conclusion

Our study provides the results of screening of the largest Bengali infertile men sample genotyped with the maximum number of STS markers spanning the entire length of Y chromosome long arm. Y chromosome microdeletion is a significant genetic etiology of infertility among Bengali men.

"Second-look" Micro Testicular Sperm Extraction (MicroTESE) in Patients with Non-obstructive Azoospermia Following Histopathological Analysis

Introduction:

Microdissection testicular sperm extraction (microTESE) is considered the gold standard method for surgical sperm retrieval among patients with non-obstructive azoospermia (NOA).

Aim:

This study aimed to evaluate the correlation between histopathological findings after failed microTESE procedure and outcomes of the „second-look“ procedure and to provide insight into the most common histopathological patterns after testicular biopsy within our population.

Methods:

The retrospective study included 33 selected patients with NOA, who had undergone unsuccessful sperm retrieval. The diagnosis of NOA was made after the assessment of the patient’s history data, a physical examination, semen analysis, the hormonal profile, and genetic studies. After negative sperm retrieval, histopathological report has been analyzed for „second-look“ microTESE attempt.

Results:

Five testicular histopathological patterns were found: hypospermatogenesis (9,1%), Sertoli cell-only syndrome (43%), germ cell maturation arrest (15%), seminiferous tubule hyalinization (15%), mixed pattern (21%). Y-microdeletions were detected in 5 patients, of which 3 patients showed AZFc region deletions. Only 3 patients (9,1%) underwent a „second-look“ procedure after the evaluation of histopathological reports. After the stimulation therapy and „second-look“ procedure, we had a positive outcome in a single patient (33,3%). Mean FSH value in patients with confirmed spermatogenesis was 17.26±3.11IU/l, while mean FSH value in patients without presence or germ cell statistically significantly exceeded and was 24.28±4.71IU/L (p=0.038).

Conclusion:

Histopathological reports following the microTESE procedure are obligatory for the proper selection of patients who are candidates for the „second-look“ microTESE attempt. Patients with Sertoli cell-only syndrome and hypospermatogenesis particularly can benefit from the “second-look” procedure.

Y chromosome microdeletion and cytogenetic findings in male infertility: A cross-sectional descriptive study

Background

Infertility affects about 15% of couples worldwide, and the male factor alone is responsible for approximately 50% of the cases. Genetic factors have been found to play important roles in the etiology of azoospermia and severe oligospermia conditions that affect 30% of individuals seeking treatment at infertility clinics.

Objective

To determine the frequency of chromosomal abnormalities and Y chromosome microdeletion in infertile men.

Materials and Methods

A total of 100 infertile men with abnormal semen parameters were included in this study from 2014 to 2018. Chromosomal analysis was carried out using standard G-banding using Trypsin Giemsa protocol. Multiplex polymerase chain reaction was used to determine the Y microdeletion frequency.

Results

All participants were aged between 22 and 48 yr with a mean and standard deviation of 35.5 ± 5.1. Of the 100 subjects included in the study, three had Klinefelter syndrome-47,XXY, one had balanced carrier translocation-46,XY,t(2;7)(q21;p12), one with the balanced carrier translocation with inversion of Y chromosome 45,XY,der(13;14)(q10;q10),inv(Y), one had polymorphic variant of chromosome 15, one had Yqh-, and another had an inversion of chromosome 9. Y chromosome microdeletion of Azoospermia factor c region was observed in 2% of the cases. To the best of our knowledge, the current study is the first reported case with unique, balanced carrier translocation of chromosome 2q21 and 7p21.

Conclusion

The present study emphasizes the importance of routine cytogenetic screening and Y microdeletion assessment for infertile men, which can provide specific and better treatment options before undergoing assisted reproductive technology during genetic counseling.

Clinical presentations and semen characteristics of men attending the secondary referral infertility clinic at Mumbai, India

Background:

Limited information is available on the aetiology and semen profiles of male infertility in Indian population.

Aim:

The aim of this study is to study the clinical and semen characteristics of men attending the infertility clinic and also to understand the impact of World Health Organization (WHO) 2010 reference values on the diagnosis of male infertility.

Setting and Design:

A retrospective study evaluating the medical case records (January 2005 to December 2015, [n = 1906]) of men attending infertility clinic in Mumbai, India.

Materials and Methods:

The aetiology was classified based on the andrology evaluation and other investigations. Semen profiles were compared during the years 2005–2010 and 2011–2015 using WHO 1999 and WHO 2010 criteria, respectively.

Statistical Analysis:

The Chi-square and Mann–Whitney U tests were performed using Open Source Epidemiological software and Social science calculators.

Results:

The aetiology of male infertility was determined in 62% of the men; while the cause remained undetermined in 38%. Varicocele (25%), urogenital infections (10%), sexual dysfunctions (8%) and vas aplasia (8%) were identified as major aetiologies in our cohort. Men with sexual dysfunctions and vas aplasia were significantly higher during the years 2011–2015 as compared to 2005–2010. Men having normozoospermia (10%) and azoospermia (3%) were increased, whereas those having oligoasthenozoospermia (17%) were reduced in 2011–2015 as compared to 2005–2010. According to WHO 1999 criteria , 12-15% of men showed abnormal semen profiles. The semen parameters of these men became normal on using WHO 2010 reference values.

Conclusions:

Varicocele is the most common aetiology in infertile men. Idiopathic infertility was seen in a higher proportion among the infertile men.

External and Genetic Conditions Determining Male Infertility

We explain environmental and genetic factors determining male genetic conditions and infertility and evaluate the significance of environmental stressors in shaping defensive responses, which is used in the diagnosis and treatment of male infertility. This is done through the impact of external and internal stressors and their instability on sperm parameters and their contribution to immunogenetic disorders and hazardous DNA mutations. As chemical compounds and physical factors play an important role in the induction of immunogenetic disorders and affect the activity of enzymatic and non-enzymatic responses, causing oxidative stress, and leading to apoptosis, they downgrade semen quality. These factors are closely connected with male reproductive potential since genetic polymorphisms and mutations in chromosomes 7, X, and Y critically impact on spermatogenesis. Microdeletions in the Azoospermic Factor AZF region directly cause defective sperm production. Among mutations in chromosome 7, impairments in the cystic fibrosis transmembrane conductance regulator CFTR gene are destructive for fertility in cystic fibrosis, when spermatic ducts undergo complete obstruction. This problem was not previously analyzed in such a form. Alongside karyotype abnormalities AZF microdeletions are the reason of spermatogenic failure. Amongst AZF genes, the deleted in azoospermia DAZ gene family is reported as most frequently deleted AZF. Screening of AZF microdeletions is useful in explaining idiopathic cases of male infertility as well as in genetic consulting prior to assisted reproduction. Based on the current state of research we answer the following questions: (1) How do environmental stressors lessen the quality of sperm and reduce male fertility; (2) which chemical elements induce oxidative stress and immunogenetic changes in the male reproductive system; (3) how do polymorphisms correlate with changes in reproductive potential and pro-antioxidative mechanisms as markers of pathophysiological disturbances of the male reproductive condition; (4) how do environmental stressors of immunogenetic disorders accompany male infertility and responses; and (5) what is the distribution and prevalence of environmental and genetic risk factors.

The Association of Partial Azoospermia Factor C Deletions and Male Infertility in Northwestern China

BACKGROUND

Male infertility is a major health issue worldwide. Y chromosome microdeletions are well-characterized genetic causes of male infertility. The association of partial AZFc deletions (gr/gr, b2/b3, and b1/b3) with male infertility is not well confirmed in diverse populations. The purpose of the present study was to investigate the frequency of partial AZFc deletions and their association with male infertility in a population from Northwestern China.

METHODS

Multiplex polymerase chain reaction was used to detect partial AZFc deletions in 228 infertile patients. We analyzed 141 cases of azoospermia (AS), 87 cases of oligozoospermia (OS), and 200 fertile controls.

RESULTS

Our data showed that the frequency of a b2/b3 deletion in infertile men, men with AS, men with OS, and controls was 3.51, 2.13, 5.75, and 0.00%, respectively. The frequency of this deletion was significantly different between the infertile group and the control group (3.51 vs. 0.00%, respectively, p = 0.021) and between the OS group and the control group (5.75 vs. 0.00%, respectively, p = 0.003). The frequency of a gr/gr deletion in each group was 11.84, 9.22, 16.09, and 7.50%, respectively. The frequency of a gr/gr deletion was significantly different between the OS group and the control group (16.09 vs. 7.50%, respectively, p = 0.026) but not between the infertile group and the control group (11.84 vs. 7.50%, p = 0.132) or the AS group and the control group (9.22 vs. 7.50%, p = 0.569). The frequency of a b1/b3 deletion was 0.44, 0.71, 0.00, and 3.00%, respectively. For this deletion, there was no significant difference between the infertile (0.44 vs. 3.00%, p = 0.089), AS (0.71 vs. 3.00%, p = 0.276), and OS groups (0.00 vs. 3.00%, p = 0.236) and the control group.

CONCLUSIONS

Our results suggest that the b2/b3 deletion might be associated with male infertility and that the gr/gr deletion might be associated with spermatogenic failure in men with OS in Northwestern China (Ningxia).

Consequences of Y chromosome microdeletions beyond male infertility

PURPOSE

The human Y chromosome plays a central role in sex determination and spermatogenesis. The azoospermia factor (AZF) loci on the Y chromosome contain genes that were thought to be testis specific with their deletions leading to spermatogenic failure. However, beyond the testis, the AZF genes (mainly those in AZFa and AZFb loci) are widely expressed in multiple tissues. Further, these genes are predicted to play roles in processes such as gene regulation and protein synthesis. These observations suggest that the AZF genes may have functions beyond regulation of fertility.

RESULTS

Three major areas have emerged where alternations in AZF genes have effects beyond infertility. (1) Poor-quality embryos are generated in assisted reproduction when sperm from men harboring Y chromosome microdeletions are used, (2) a higher preponderance of neuropsychiatry disorders is observed in men with deletions in AZF genes, and (3) copy number variations and altered expression of AZF genes are found in several cancers.

CONCLUSION

While our data is preliminary and observational in nature, systematic studies are required to address how genetic alterations in the Y chromosome can affect the health of men beyond infertility. This information will provide a different perspective in the area of androgenetics and have implications in devising strategies for maintaining the overall well-being of infertile males.

High frequencies of Non Allelic Homologous Recombination (NAHR) events at the AZF loci and male infertility risk in Indian men

Deletions in the AZoospermia Factor (AZF) regions (spermatogenesis loci) on the human Y chromosome are reported as one of the most common causes of severe testiculopathy and spermatogenic defects leading to male infertility, yet not much data is available for Indian infertile men. Therefore, we screened for AZF region deletions in 973 infertile men consisting of 771 azoospermia, 105 oligozoospermia and 97 oligoteratozoospermia cases, along with 587 fertile normozoospermic men. The deletion screening was carried out using AZF-specific markers: STSs (Sequence Tagged Sites), SNVs (Single Nucleotide Variations), PCR-RFLP (Polymerase Chain Reaction - Restriction Fragment Length Polymorphism) analysis of STS amplicons, DNA sequencing and Southern hybridization techniques. Our study revealed deletion events in a total of 29.4% of infertile Indian men. Of these, non-allelic homologous recombination (NAHR) events accounted for 25.8%, which included 3.5% AZFb deletions, 2.3% AZFbc deletions, 6.9% complete AZFc deletions, and 13.1% partial AZFc deletions. We observed 3.2% AZFa deletions and a rare long AZFabc region deletion in 0.5% azoospermic men. This study illustrates how the ethnicity, endogamy and long-time geographical isolation of Indian populations might have played a major role in the high frequencies of deletion events.

Cytogenetic and molecular characterization of an oligoasthenozoospermia male carrier of an unbalanced Y;22 translocation: A case report

RATIONALE

Y;autosome translocations are associated with male infertility and azoospermia. Some carriers with a Y:22 translocation can produce offspring and transmit the translocation through generations without phenotypic repercussion. Hence, the clinical features of carriers with certain Y chromosome abnormalities remain uncertain.

PATIENT CONCERNS

An apparently healthy 33-year-old man, 175 cm tall and weighing 60 kg had a 6-month history of primary infertility.

DIAGNOSES

The patient was diagnosed with oligoasthenozoospermia. A series of examinations have been performed to evaluate possible genetic causes of this diagnosis. Several methods included semen analysis, hormone measurements, cytogenetic analysis, and high-throughput multiplex ligation-dependent probe amplification semiconductor sequencing.

INTERVENTIONS

The patient underwent detailed genetic counseling. Cytogenetic analysis was advised for his father. Preimplantation genetic diagnosis was performed to improve potential pregnancy success rate.

OUTCOMES

Semen analysis revealed oligoasthenozoospermia. Hormone levels were within the normal limits. The karyotype of the patient and his father was 45,X,der(Y;22). Sequencing results indicated the presence of the sex-determining region on the Y chromosome gene. Y-chromosome microdeletion detection showed the presence of AZF (azoospermic factor)a, AZFb, and AZFc regions, but deletion of b2/b3 and duplication of b3/b4 regions.

LESSONS

A clinical karyotype report involving a Y chromosome abnormality should consider the results of semen analysis, which helps to identify the chromosomal breakpoint. Semiconductor sequencing technology was useful for clarifying AZF gene microdeletions.

Independent of DAZL-T54A variant and AZF microdeletion in a sample of Egyptian patients with idiopathic non-obstructed azoospermia

Background

The microdeletion events that occur in the Y chromosome-azoospermia factor (AZF) region may lead to dyszoospermia. Also, the deleted azoospermia (DAZ) gene on AZFc and autosomal deleted azoospermia like gene (DAZL) are suggested to represent impairment, so it is interesting to determine the independency pattern of the AZF region and DAZL gene in azoospermic patients.

Aim

To study the molecular characterization of AZFc and DAZL in 64 idiopathic non-obstructed azoospermia patients and 30 sexually reproductive men.

Methods

SYBR Green I (Q-PCR) and AZF-STS analysis was used for DAZ gene, and SNV-PCR and confirmative Sanger sequencing for DAZL gene.

Results

The present study observed that 15.6% had AZFc microdeletion, out of which 10% had DAZ1/2 deletion, and no T54A variant in the DAZL gene was found.

Conclusion

In the current work, the novelty is that spermatogenic impairment phenotype, present with AZFc microdeletions, is independent of the T54A variant in the DAZL gene, and AZFc microdeletions could be a causative agent in spermatogenic impairment.

Y-chromosome microdeletions in nonobstructive azoospermia and severe oligozoospermia

The aim of the present work was to present the outcomes of the patients with Y-chromosome microdeletions treated by intracytoplasmic sperm injection (ICSI), either using fresh (TESE) or frozen-thawed (TESE-C) testicular sperm and ejaculated sperm (EJAC). The originality of this work resides in the comparisons between the different types of Y-microdeletions (AZFa, AZFb, and AZFc) and treatments, with detailed demographic, stimulation, embryological, clinical, and newborn (NB) outcomes. Of 125 patients with Y-microdeletions, 33 patients presented severe oligozoospermia (18 performed ICSI with ejaculated sperm) and 92 secretory azoospermia (65 went for TESE with 40 having successful sperm retrieval and performed ICSI). There were 51 TESE treatment cycles and 43 TESE-C treatment cycles, with a birth of 19 NB (2 in AZFa/TESE-C, 12 in AZFc/TESE, and 5 in AZFc/TESE-C). Of the 29 EJAC cycles, there was a birth of 8 NB (in AZFc). In TESE and EJAC cycles, there were no significant differences in embryological and clinical parameters. In TESE-C cycles, there was a significant lower oocyte maturity rate, embryo cleavage rate and mean number of embryos transferred in AZFb, and a higher mean number of oocytes and lower fertilization rate in AZFc. In conclusion, although patients with AZFc microdeletions presented a high testicular sperm recovery rate and acceptable clinical outcomes, cases with AZFa and AZFb microdeletions presented a poor prognosis. Due to the reported heredity of microdeletions, patients should be informed about the infertile consequences on NB and the possibility of using preimplantation genetic diagnosis for female sex selection.

Genetics of the human Y chromosome and its association with male infertility

The human Y chromosome harbors genes that are responsible for testis development and also for initiation and maintenance of spermatogenesis in adulthood. The long arm of the Y chromosome (Yq) contains many ampliconic and palindromic sequences making it predisposed to self-recombination during spermatogenesis and hence susceptible to intra-chromosomal deletions. Such deletions lead to copy number variation in genes of the Y chromosome resulting in male infertility. Three common Yq deletions that recur in infertile males are termed as AZF (Azoospermia Factor) microdeletions viz. AZFa, AZFb and AZFc. As estimated from data of nearly 40,000 Y chromosomes, the global prevalence of Yq microdeletions is 7.5% in infertile males; however the European infertile men are less susceptible to Yq microdeletions, the highest prevalence is in Americans and East Asian infertile men. In addition, partial deletions of the AZFc locus have been associated with infertility but the effect seems to be ethnicity dependent. Analysis of > 17,000 Y chromosomes from fertile and infertile men has revealed an association of gr/gr deletion with male infertility in Caucasians and Mongolian men, while the b2/b3 deletion is associated with male infertility in African and Dravidian men. Clinically, the screening for Yq microdeletions would aid the clinician in determining the cause of male infertility and decide a rational management strategy for the patient. As these deletions are transmitted to 100% of male offspring born through assisted reproduction, testing of Yq deletions will allow the couples to make an informed choice regarding the perpetuation of male infertility in future generations. With the emerging data on association of Yq deletions with testicular cancers and neuropsychiatric conditions long term follow-up data is urgently needed for infertile men harboring Yq deletions. If found so, the information will change the current the perspective of androgenetics from infertility and might have broad implication in men health.

Gene Scanning for Microdeletions in the Azoospermia Factor Region of Y-Chromosome in Infertile Men of Gujarat, India

INTRODUCTION

Azoospermia Factor (AZF) microdeletions in Yq chromosome is one of the most frequent genetic cause associated with failure of spermatogenesis in males with infertility.

AIM

To figure out the Yq chromosome microdeletions frequency in infertile men from Gujarat region of India.

MATERIALS AND METHODS

In this study, 141 infertile men with azoospermia (n=41) and oligozoospermia (n=100) were examined along with 159 normozoospermic men. Eleven different markers spanning the azoospermia factor region of human Yq chromosome, amplified by sequence-tagged site Polymerase Chain Reaction (PCR) to detect the microdeletions. Sperm morphological analysis was done using papanicolau staining method.

RESULTS

Thirty four infertile men out of 141 presented Yq chromosome microdeletions. The frequency of AZF microdeletions was 31.71% in azoospermia and 21% in oligozoospermia patients. Only two oligozoospermia patients showed morphological defects.

CONCLUSION

Due to the presence of high frequency of Yq chromosome microdeletions in Gujarati infertile men, it is imperative to implement the AZF microdeletion screening in such patients as it results in male spermatogenesis dysfunctioning.

Computational Analysis of High Risk Missense Variant in Human UTY Gene: A Candidate Gene of AZFa Sub-region

BACKGROUND

The human Ubiquitously transcribed tetratricopeptide repeat gene, Y-linked (UTY) gene encodes histone demethylase involved in protein-protein interactions. UTY protein evidence at protein level predicted intracellular and secreted protein. UTY is also involved in spermatogenesis process.

METHODS

The high-risk non-synonymous single nucleotide polymorphism in the coding region of the UTY gene was screened by SNP database and identified missense variants were subjected to computational analysis to understand the effect on protein function, stability and structure by SIFT, PolyPhen 2, PANTHER, PROVEAN, I-Mutant 2, iPTREE-STAB, ConSurf, ModPred, SPARKS-X, QMEAN, PROCHECK, project HOPE and STRING.

RESULTS

A total of 151 nsSNPs variants were retrieved in UTY gene out of which one missense variant (E18D) was predicted to be damaging or deleterious using SIFT, PolyPhen 2, PANTHER and PROVEAN. Additionally, E18D variant showed less stability, high conservation and having role in post translation modification using i-Mutant 2 and iPTREE-STAB, ConSurf and ModPred, respectively. The predicted 3D model of UTY using SPARKS-X with z-score of 15.16 was generated and validated via QMEAN (Z-score of 0.472) and PROCHECK which plots Ramachandran plot (85.3% residues in most favored regions, 12.3% in additionally allowed regions, 2.0% in generously allowed regions and 4.0% were in disallowed regions) and it indicates a good quality model. STRING showed that UTY interacts with ten different proteins.

CONCLUSION

This study revealed that SNP data available on database was deduced to find out the most damaging nsSNPs i.e. rs3212293 (E18D). Therefore, it provides useful information about functional SNPs for future prospects concerning infertility in men.

Correlation of genetic results with testicular histology, hormones and sperm retrieval in nonobstructive azoospermia patients with testis biopsy

To investigate the frequency and types of genetic results in different testicular histology of patients with nonobstructive azoospermia (NOA), and correlated with hormones and sperm retrieval (SR), a retrospective study was conducted in 286 Chinese NOA patients who underwent testis biopsy and 100 age-matched fertile men as the control group. Chromosome karyotype analyses were performed by the peripheral blood chromosome G-band detection method. Screening of Y chromosome microdeletions of azoospermia factor (AZF) region was performed by polymerase chain reaction (PCR) amplification of 11 sequence-tagged sites (STS). The serum levels of follicle-stimulating hormone, luteinising hormone and testosterone (T) and the appearance of scrotal ultrasound were also obtained. In 286 cases of NOA, 14.3% were found to have chromosomal alterations. The incidence of chromosomal abnormality was 2.8%. Sex chromosomal abnormalities were seen in six cases (four cases of Klinefelter's syndrome (47, XXY) and two cases of mosaics). The incidence of polymorphic chromosomal variants was 3% in the normal group and 11.5% in the NOA group. In total, 15.7% of NOA patients were found to have AZF microdeletions and AZF (c + d) was the most frequent one. The results of hormone and SR were found to be significantly different among all testicular histological types, whereas no significant differences were found when it comes to genetic alterations. It is concluded that the rate of cytogenetic alterations was high in NOA patients. So screening for chromosomal alterations and AZF microdeletions would add useful information for genetic counselling in NOA patients with testis biopsy and avoid vertical transmission of genetic defects by assisted reproductive technology.

Spermatogenesis in humans and its affecting factors

Spermatogenesis is an extraordinary complex process. The differentiation of spermatogonia into spermatozoa requires the participation of several cell types, hormones, paracrine factors, genes and epigenetic regulators. Recent researches in animals and humans have furthered our understanding of the male gamete differentiation, and led to clinical tools for the better management of male infertility. There is still much to be learned about this intricate process. In this review, the critical steps of human spermatogenesis are discussed together with its main affecting factors.

Deletion of GOLGA2P3Y but not GOLGA2P2Y is a risk factor for oligozoospermia

The AZFc locus on the human Y chromosome harbours several multicopy genes, some of which are required for spermatogenesis. It is believed that deletion of one or more copies of these genes is a cause of infertility in some men. GOLGA2LY is one of the genes in the AZFc locus and it exists in two copies, GOLGA2P2Y and GOLGA2P3Y. The involvement of GOLGA2LY gene copy deletions in male infertility, however, is unknown. This study aimed to investigate the association of deletions of GOLGA2P2Y and GOLGA2P3Y gene copies with male infertility and with sperm concentration and motility. The frequency of GOLGA2P3Y deletion was significantly higher in oligozoospermic men compared with normozoospermic men (7.7% versus 1.2%; P = 0.0001), whereas the frequency of GOLGA2P2Y deletion was comparable between oligozoospermic and normozoospermic men (10.3% versus 11.3%). The deletion of GOLGA2P3Y but not GOLGA2P2Y was significantly higher (P = 0.03) in men with gr/gr rearrangements, indicating that GOLGA2P3Y deletions increase the susceptibility of men with gr/gr rearrangements to oligozoospermia. Furthermore, men with GOLGA2P3Y deletion had reduced sperm concentration and motility compared with men without deletion or with deletion of GOLGA2P2Y. These findings indicate GOLGA2P3Y gene copy may be candidate AZFc gene for male infertility.

Prevalence of Y Chromosome Microdeletions in Idiopathic Azoospermia Cases in Central Indian Men

BACKGROUND

Genetic factor is important determinant of human male fertility, it is involved in 10-15% infertile males. Chromosome abnormalities and Y chromosome microdeletions are the main genetic causative factors for infertility. The frequency of male infertility & microdeletions in Y chromosome are also related to ethnic, geographical variations. In this study, we evaluated the prevalence of chromosomal abnormalities and microdeletions of Y chromosome in infertile azoospermia cases in central India to assess the geographical or population based variations.

MATERIALS AND METHODS

We have studied 160 non-obstructive azoospermia cases to find out frequency of chromosomal abnormalities and Y chromosome microdeletions of AZF locus. G-banding method was used for exclusion of chromosomal abnormalities. One hundred and forty eight azoospermic infertile men were screened using 12 sequence-tagged-sites (STS) primers of AZFa, AZFb, AZFc region and SRY gene (Yp) region by polymerase chain reactions.

RESULTS

Out of 160 azoospermic infertile males, 12 (7.5%) confirmed chromosomal abnormalities and Klinefelter's syndrome was predominantly cause of azoospermia. Of the 148 infertile males, 19 (12.8%) were shown microdeletions in different AZF regions. Deletions in AZFa region were 2.02% and 3.37% was in AZFb whereas high frequencies of deletions (6.08%) in AZFc were recorded in azoospermic males. In two azoospermic males were shown microdeletions in AZFb+c loci.

CONCLUSION

The prevalence of Y chromosome microdeletions in azoospermic men was 12.8% in this geographical region. Klinefelter's syndrome is important cause in male infertility. So, the screening of Y microdeletions is essential.

Susceptibility of gr/gr rearrangements to azoospermia or oligozoospermia is dependent on DAZ and CDY1 gene copy deletions

PURPOSE

The purpose of this study was to determine the association of AZFc subdeletions (gr/gr, b1/b3 and b2/b3) and deletion of DAZ and CDY1 gene copies with male infertility

METHODS

Three hundred twelve controls, 172 azoospermic and 343 oligozoospermic subjects were subjected to AZFc subdeletion typing by STS PCR. Deletion of DAZ and CDY1 gene copies was done using sequence family variant analysis. Sperm concentration and motility were compared between men with and without AZFc subdeletions. Effect of the AZFc subdeletions on ICSI outcome was evaluated.

RESULTS

Amongst the three AZFc subdeletions, the frequency of gr/gr was higher in oligozoospermic (10.5 %) and azoospermic (11.6 %) men as compared to controls (5.1 %). In men with AZFc subdeltions, loss of two DAZ and one CDY1 gene copy made them highly susceptible to azoospermia and severe oligozoospermia with OR of 29.7 and 26, respectively. These subdeletions had no effect on ICSI outcome, albeit there were an increased number of poor quality embryos in AZFc subdeleted group.

CONCLUSION

AZFc subdeletions are a major risk factor for male infertility in the Indian population. In the subjects with AZFc subdeletions, the deletion of DAZ and CDY1 gene copies increases its susceptibility to azoospermia or severe oligozoospermia. Since these deletions can be vertically transmitted to the future male offspring by ICSI, it will be essential to counsel the couples for the transmission of the genetic defect in the male offspring born after assisted reproduction and the risk of perpetuating infertility in future generation.

Screening for AZFc partial deletions in Dravidian men with nonobstructive azoospermia and oligozoospermia

CONTEXT

Dravidians are the predominant population residing in South India with a diverse genetic structure. Considering various genetic discoveries taking place today, it is evident that deletions in the AZFc region are the most common cause of severe spermatogenic failure (SSF) in various populations studied. However, it is significant to note that there is a paucity of scientific literature on AZFc subdeletion screening among the Dravidian population.

OBJECTIVE

To investigate the prevalence and association of AZFc subdeletion patterns among Dravidian men with nonobstructive azoospermia (NOA) and oligozoospermia.

METHODS

A population of 354 subjects, including 120 patients with NOA, 109 with oligozoospermia, and 125 normal male controls, were screened using locus-specific sequence tag site markers.

RESULTS

We found 21 (9.17%) patients with classical AZF deletion, while no deletions were observed in controls. After excluding the samples with AZF deletions, the remaining 208 infertile and 125 control samples were screened for partial AZFc deletions using a standardized multiplex polymerase chain reaction and on analysis revealed that 13 (6.25%) of the infertile samples possessed gr/gr subdeletions and 15 (7.21%) of the infertile samples possessed b2/b3 subdeletions. Six (4.8%) of the normal samples were found to carry gr/gr subdeletions and two (1.6%) had b2/b3 deletions. The b1/b3 deletion was not observed in any of the patient and control samples screened.

CONCLUSION

Our finding shows that there is a strong association between b2/b3 subdeletion and SSF in the Dravidian population (odds ratio, 4.78; 95% confidence interval 1.07-21.26) (p=0.018). Further studies, including gene copy typing for DAZ and CDY genes and a comprehensive haplogrouping analysis, are recommended in a large and well-selected patient group to elude the genetic mechanism behind this association.

Genetic Risk of Azoospermia Factor (AZF) Microdeletions in Idiopathic Cases of Azoospermia and Oligozoospermia in Central Indian Population

BACKGROUND

Genetic factors cause about 15% of male infertility. Azoospermia factors (AZFa, AZFb, and AZFc) present on Yq are most important for spermatogenesis. We have made an attempt to evaluate the frequencies of microdeletions of AZFa, AZFb, AZFc in idiopathic cases of azoospermia and oligozoospermia from central Indian population.

MATERIALS AND METHODS

We have analyzed a total of 156 subjects (95 oligozoospermia and 61 azoospermia) & 50 control subjects. DNA samples were analyzed for microdeletions of Y chromosome by PCR-screening of 18 sequences-tagged-site (STS) markers from different region of the AZF on Yq and SRY on Yp.

RESULTS

Out of 156 cases analyzed, 13 (8.33%) subjects (8 azoospermia and 5 oligozoospermia) showed partial deletion of AZF regions, of which deletion in AZFc region was the most common (84.6%) followed by AZFb (15.4%) and AZFa (15.4%). The sites and sizes of deletions varied among patients. Histological study of the testicular tissue of the available subjects, who showed microdeletions of Y chromosome, showed spermatogenic arrest at different stages. The frequency of Y chromosome microdeletion in our subjects was 8.33%.

CONCLUSION

Some Indian studies reported low frequencies of microdeletions than that of our result. We suggest that the frequency of deletions may be affected by the involvement of different genetic factors, ethnic population and different geographical regions. PCR based Y chromosome screening for microdeletions will be useful and great help to infertility clinics for genetic counselling and assisted reproduction.

Association of progesterone receptor gene polymorphism with male infertility and clinical outcome of ICSI

PURPOSE

To investigate the association of Progesterone Receptor (PR) gene variations and male infertility

METHODS

DNA extraction, PCR and sequencing of PR gene, PROGINS insertion by PCR. Association of the variations with seminal parameters and outcomes of ICSI.

RESULTS

Four known SNPs in the PR gene were identified in the study of which three (rs3740753, rs1042838, rs104283) were co-inherited and in complete linkage disequilibrium with the PROGINS Alu insertion. There were no differences in their frequencies between fertile and infertile males. The rs2020880 was found at a very low frequency only in the controls but not in the infertile subjects. The sperm counts, fertilization rate, embryo quality or pregnancy rates were not different in individuals with or without PROGINS allele.

CONCLUSION

PR gene alterations are not associated with male infertility or ICSI outcome.