Chromosomal abnormalities and polymorphisms in infertile men

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.

Does the prognosis after PGT for structural rearrangement differ between female and male translocation carriers?

RESEARCH QUESTION

Chromosomal translocations are known genetic causes of premature ovarian insufficiency syndrome. Are certain translocations associated with decreased capacity of small antral follicles to respond to exogenous FSH? Does the prognosis after preimplantation genetic testing for structural rearrangements differ in couples with female or male translocation carriers and according to the type of translocation?

DESIGN

A single-centre, retrospective, observational study covering a 10-year period. One hundred and thirty-nine females carrying a translocation were compared with 192 partners of male translocation carriers. To evaluate ovarian response to FSH, the follicular output rate was used, defined by ratio between the pre-ovulatory follicle count on day of HCG x 100/antral follicle count (AFC). To determine a cut-off of metaphase II oocytes and biopsied embryos as predictor of obtaining a balanced embryo transfer, receiver operator characteristic curves were plotted.

RESULT

A decreased capacity of small antral follicles to respond to exogenous FSH in female translocation carriers was found. The number of metaphase II oocytes in both groups was weakly informative as a predictor of obtaining an embryo transfer. The number of biopsied embryos had some clinical value, however, and allowed a cut-off of 6.5 to be determined for female translocation carriers versus 5.5 for the partners of male translocation carriers. Live birth rates, however, were not different between female and male translocations carriers.

CONCLUSIONS

Female translocation carriers may respond poorly to ovarian stimulation, and present a higher rate of unbalanced embryos, which means that higher gonadotrophin doses may be required to increase the number of biopsied embryos.

Clinical aspects of 49 infertile males with 45,X/46,XY mosaicism karyotype: A case series

Disorders of sex development (DSD) are congenital abnormalities as an atypical development process in either gonadal or chromosomal structure. It is the cause of the abnormality in phenotype and characteristics. Chromosomal analysis plays an important role in the DSD determination. 45,X/46,XY mosaicism is a rare karyotype, and its prevalence is about 1.5 in 10,000 newborns. It affects the growth, hormonal balance, gonad development and histology. All data such as height, male general appearance, testis size and volume, external genitalia, spermogram and hormonal levels, testis pathology, Y chromosome microdeletion and karyotype, and assisted reproductive technology (ART) outcome were recorded based on patients profile and history. We investigated 64 infertile males with 45,X/46,XY mosaicism. Fifteen cases who had structural abnormalities in Y chromosome were excluded. From 49 available spermogram, 21 cases reported as azoospermic men, while 28 of them classified as nonazoospermic patients in which four of them displayed normal spermogram. According to hormonal evaluation, there were no significant differences between azoospermic and nonazoospermic groups. In azoospermia, only three couples underwent an ART cycle in which all of them failed. From 14 nonazoospermic cases who entered into the ART cycle, three cases experienced a successful pregnancy that one of the prosperous outcomes was twins. In 45,X/46,XY cases, both 45,X and 46,XY cell lines are seen. Various distributions of both cell lines can reflect a wide range of phenotypes that may be the most comprehensive evaluation in infertile males with 45,X/46,XY karyotype. It assumes that karyotyping as a main diagnostic test can enable us to find these rare cases.

Tumor risk of children with 45,X/46,XY gonadal dysgenesis in relation to their clinical presentations: Further insights into the gonadal management

OBJECTIVE

To investigate the risk of gonadal germ cell neoplasms (GCN) in children with 45,X/46,XY gonadal dysgenesis and its relation to the clinical presentations.

METHODS

We conducted a retrospective study reviewing the clinical and gonadal features of all consecutive children with 45,X/46,XY gonadal dysgenesis who received gonadal management in a tertiary center from 1985 to 2015. Study subjects were divided into Group I(significant genitalia anomaly), Group II(female phenotype) and Group III(male phenotype).

RESULTS

21 children were studied (Group I=8; Group II=11; Group III=2). All 19 children of Group I and II eventually underwent bilateral gonadectomy. One patient of Group III underwent gonadal biopsy which showed increase in fibrous tissue in the testes without any GCN. 3/8(37.5%) and 6/11(54.5%) of patients in Group I and II respectively had either gonadoblastoma (GB) or carcinoma-in-situ (CIS) or both affecting one or both gonads. Among Group I patients, the 4 dysgenetic testes affected by CIS in 3 patients were intraabdominal (n=1), inguinal (n=1) and scrotal (n=2) in positions. Among Group II patients, 6/20 streak gonads had GB and 2/2 dysgenetic testes had GB or CIS.

CONCLUSIONS

45,X/46,XY children with significant genitalia anomaly or female phenotype are both at high risk of gonadal GCN.

Does thalassemia influence ovarian response? An analysis of 127 cycles involving pre-implantation genetic diagnosis of thalassemia in southern China

To evaluate the impact of thalassemia carrier status on the response to controlled ovarian stimulation (COS) and outcome of intracytoplasmic sperm injection (ICSI). Seventy couples that both carried a mutation attributed to thalassemia (PGD group) and 57 couples in which only the father was a thalassemia carrier (CON group) were enrolled. All female subjects received long protocol GnRH agonist stimulation and received equivalent doses of recombinant follicle-stimulating hormone and the number of retrieved oocytes and utilisable embryos did not differ significantly. The endometrial thickness at human chorionic gonadotropin (hCG) administration day and the number of transferable embryos was lower in the PGD groups. However, pregnancy outcomes, including the clinical pregnancy rate and ongoing pregnancy rate, did not differ significantly between the two groups per cycle. Ovarian response to COS is not impaired by maternal thalassemia carrier status and embryo biopsy did not impair preimplantation embryo development or pregnancy outcomes.

Meiotic abnormalities in metaphase I human spermatocytes from infertile males: frequencies, chromosomes involved, and the relationships with polymorphic karyotype and seminal parameters

The aim of this study was to look in depth at the relationship between meiotic anomalies and male infertility, such as the determination of the chromosomes involved or the correlation with patient features. For this purpose, a total of 31 testicular tissue samples from individuals consulting for fertility problems were analyzed. Metaphase I cells were evaluated using a sequential methodology combining Leishman stained procedures and multiplex fluorescence in situ hybridization protocols. The number of chromosomal units and chiasmata count per bivalent were established and a hierarchical cluster analysis of the individuals was performed. The relationship of the seminogram and the karyotype over recombination were evaluated using Poisson regression models. Results obtained in this study show a significant percentage of infertile individuals with altered meiotic behavior, mostly specified as a reduction in chiasmata count in medium and large chromosomes, the presence of univalents, and the observation of tetraploid metaphases. Moreover, the number and the type of anomalies were found to be different between cells of the same individual, suggesting the coexistence of cell lines with normal meiotic behavior and cell lines with abnormalities. In addition, chromosomal abnormalities in metaphase I are significantly associated with oligozoospermia and/or polymorphic karyotype variants.

Genetics and male infertility

The goal of this review is to explain the requirement for understanding the genetic structure of infertility arising from male factor and to discuss the essentials of these genetic elements (2). The majority of the population is affected by this disorder caused by male factor infertility (1); but the etiologies are still unknown. After the primary genetic structure in infertile phenotypes is searched, an evaluation can be made. Thus the reasons causing infertility can be discovered and patients can benefit from effective therapies (1). Publications about male infertility within the recent 10 years in the Pubmed database were discussed (1). There are some approachments for describing the function of specific genes, but no adequate study is present to be useful for diagnosing and treating male infertility (1). Male fertility and fertility in offspring of males are considerably affected by the exact transition of epigenetic information (1). When the genetic factors playing a role in male infertility were analysed, significant steps will be taken for treating patients and determining the reasons of idiopathic infertility (1). Developments in technology associated with the impact of genetics may enable to specify the etiology of male infertility by determining specific infertile phenotype marks (1).

The Low Prevalence of Y Chromosomal Microdeletions is Observed in the Oligozoospermic Men in the Area of Mato Grosso State and Amazonian Region of Brazilian Patients

OBJECTIVE

To determine the prevalence of chromosomal abnormalities and microdeletions on Y chromosome in infertile patients with oligozoospermia or azoospermia in Mato Grosso state, Brazil.

METHODS

This cross-sectional study enrolled 94 men from infertile couples. Karyotype analysis was performed by lymphocyte culture technique. DNA from each sample was extracted using non-enzymatic method. Microdeletions were investigated by polymerase chain reaction (PCR).

RESULTS

With the use of cytogenetic analysis, five patients (5.3%) had abnormal karyotype, one azoospermic patient (1.1%) had karyotype 46,XY,t(7;1) (qter-p35), one (1.1%) with mild oligozoospermia had karyotype 46,XY,delY(q), and two other azoospermic patients had karyotype 47,XXY, consistent with Klinefelter syndrome (KS). One of them (1.1%) with severe oligozoospermia had karyotype 46,XY,8p+. Microdeletion on Y chromosome was found in the azoospermia factor c (AZFc) region in only one azoospermic patient (1.1%).

CONCLUSIONS

The prevalence of genetic abnormalities in oligo/azoospermic Brazilian men from infertile couple was 5.3%, and microdeletion on Y chromosome was not a common finding in this population (1.1%).

A preliminary study of the relationship between the long arm of the Y chromosome (Yqh+) and reproductive outcomes in IVF/ICSI-ET

OBJECTIVE

To compare the reproductive outcomes of Yqh+-carrying and control couples undergoing IVF/ICSI treatments.

STUDY DESIGN

Retrospective analysis of 72 Yqh+ carriers and 986 Yqh+ non-carriers undergoing their first cycle of ART in a single centre between August 2005 and May 2011.

RESULTS

Yqh+ carrying couples had significantly worse reproductive outcomes compared with control couples undergoing IVF treatment. There were a significantly higher cancellation rate (20.69% vs 7.9%; P<0.05; OR, 3.03; CI, 1.18-7.79) and a significant lower fertilisation rate (50.05% vs 66.01%; P<0.05; OR, 0.61; CI, 0.49-0.57), implantation rate (8.33% vs 20.87%; P<0.05; OR, 0.35; CI, 0.14-0.87), good quality embryo ratio (44.70% vs 57.89%; P<0.05; OR, 0.59; CI, 0.43-0.80) and clinical pregnancy rate (17.39% vs 39.59%; P<0.05; OR, 0.32; CI, 0.11-0.96) in Yqh+ group compared with control group undergoing IVF treatment. Yqh+ carrying couples had similar reproductive outcomes compared with control couples undergoing ICSI treatment.

CONCLUSIONS

The Y chromosome polymorphic variant Yqh+ most likely plays a role in infertility. Yqh+ couples with poor reproductive outcomes in IVF treatment can be advised to undergo ICSI to improve their reproductive results in the next cycle.

Impaired puberty, fertility, and final stature in 45,X/46,XY mixed gonadal dysgenetic patients raised as boys

CONTEXT

Gender assignment followed by surgery and hormonal therapy is a difficult decision in the management of 45,X/46,XY patients with abnormal external genitalia at birth considering the paucity of studies evaluating pubertal development and fertility outcome, most notably for patients raised as boys.

OBJECTIVE

The purpose of this study was to describe the pubertal course of 20 45,X/46,XY patients born with ambiguous genitalia and raised as boys.

METHODS

This is a multicenter retrospective study.

RESULTS

Mean age at study was 25.6±2.4 years. Eighty-five percent of the patients presented a 'classical' mixed gonadal dysgenetic phenotype at birth. Puberty was initially spontaneous in all but three boys, although in six other patients, testosterone therapy was subsequently necessary for completion of puberty. Sixty-seven percent of the remaining patients presented signs of declined testicular function at the end of puberty (increased levels of FSH and low levels of testosterone and/or inhibin B). Moreover, an abnormal structure of the Y chromosome, known to alter fertility, was found in 10 out of 16 (63%) patients. Two patients developed testicular cancer. Half of the patients have adult penile length of <80 mm. Mean adult height is 156.9±2 cm, regardless of GH treatment.

CONCLUSIONS

In summary, 45,X/46,XY children born with ambiguous genitalia and raised as boys have an altered pubertal course and impaired fertility associated with adult short stature, which should, therefore, be taken into consideration for the management of these patients.

CHROMOSOMAL ABNORMALITIES IN PATIENTS WITH AZOOSPERMIA IN WESTERN MEXICO

In order to assess the frequency of chromosomal abnormalities in azoospermic males from western Mexico, we carried out a retrospective study in 227 patients. Forty-three (18.9%) cases with an abnormal karyotype were found. The most frequent chromosomal anomaly was 47,XXY, which was identified in 35 subjects (15.4%). In six cases (2.6%), structural aberrations were detected: two Robertsonian translocations [(45,XY,t(13;22)(p11;p11) and (45,XY,t(13;15)(p11;p11)], a Y;autosome translocation [46,XY,der(15)t(Y;15)(q12;p11)], and three mosaics [mos45,X/46,X,idic(Y)(q11)]. In general, these findings are in accordance with those from other surveys and confirm that the XXY aneuploidy is the most frequent chromosomal abnormality in azoospermic individuals.

GENETIC ANOMALIES DETECTED IN PATIENTS WITH NON-OBSTRUCTIVE AZOOSPERMIA AND OLIGOZOOSPERMIA

Genetic factors have a major importance in male infertility etiology. Numerical and structural chromosomal abnormalities seem to be frequent inoligospermia and azoospermia cases with unknown etiology. In this study, 819 patients with azoospermia (383) and oligospermia (436) who attended the infertility department between 1995-2005 were evaluated. Spermogram and basic hormone proties (FSH-testosterone) were studied two times in a one month interval from each patient, and all the cases were evaluated cytogenetically. The 47 (12%) of 383 azoospermia patients and the 20 (4%) of 436 oligospermia patients were found to have chromosomal abnormalities. The 9 (19%) of the chromosomal abnormalities found in azoospermia patients were autosomal and the 38 (80%) were gonosomal. In oligospermia cases, the 8 (40%) of the chromosomal abnormalities were autosomal and 12 (60%) were gonosomal. Cytogenetic analysis and genetic counseling would be helpful in infertile males with azoospermia and oligospermia by determining the genetic factors causing infertility and by assessing the genetic risks of the offsprigs provided by assisted reproductive techniques.

CHROMOSOMAL ABNORMALITIES AND POLYMORPHISMS IN MEXICAN INFERTILE MEN

A cross-sectional study was conducted to estimate the prevalence of chromosome abnormalities and normal variable chromosome features (polymorphisms) in infertile men from northeastern Mexico. Karyotyping was carried out in 326 men with diagnosis of infertility. The sperm counts showed 204 patients with oligozoospermia, 87 with azoospermia and 35 normozoospermia. Five patients with oligozoospemia and two with azoospermia presented chromosome abnormalities. Nonzoospermic men did not show chromosomal abnormalities. Polymorphisms of heterochromatin and satellite length showed a significant increased in oligozoospermic and azoospermic men with respect to normozoospermic men, respectively. This study reports the prevalence of chromosome abnormalities, polymorphisms of heterochromatin length, and polymorphisms in satellites in Mexican infertile men. The prevalence in this study was similar to other studies in world literature.

Cytogenetic analyses in infertile men

In order to assess the significance of chromosome abnormalities and polymorphic chromosomal variants in male infertility, the results of cytogenetic studies of 90 patients (32 azoospermic and 58 oligozoospermic men) were compared with those of 30 control fertile men in Estonia. Total chromosome alterations were revealed in 47.8% of infertile men. Major chromosomal abnormalities had a 10-fold increase (13.4%) in infertile males (15.6% in azoospermics and 12% in oligozoospermics) compared to the control group. In azoospermics, the most prevalent were sex chromosomal abnormalities (47,XXY)(12%), whereas a Robertsonian translocation, t(13;14) was found in one patient (3.1). In contrast, in the oligospermia group the most frequent abnormalities were autosomal (10%), of which 6.9% were translocations. Sex chromosomal abnormalities were found very rarely (1.7%). Incidence of chromosomal variants was high (38%), but similar in all groups. The most frequently observed polymorphisms involved chromosome 9. In conclusion, chromosomal abnormalities found with a high frequency in infertile males are a major cause of male infertility, and justify the requirement of cytogenetic analysis in every infertile man.

Is there a possible correlation between chromosomal variants and spermatogenesis?

AIM

Heterochromatin polymorphism is considered a variant of a normal karyotype but is more frequent in infertile men. The aim of this study was to evaluate the correlation between heterochromatic variants and male infertility and to discuss the possible mechanisms of how heterochromatic polymorphism might affect spermatogenesis.

METHODS

Cytogenetic analysis was undertaken in 210 infertile males who had been taken into assisted reproductive techniques and in 183 men with proven fertility. Additionally, C-banding was performed in men with heterochromatin polymorphism. Sperm fluorescence in situ hybridization (FISH) was applied in 54 men with normal karyotype presenting either normal or abnormal sperm parameters as well as in 8 men with heterochromatin polymorphism. The outcomes of assisted reproductive techniques were compared between infertile men with normal karyotype and men with heterochromatin polymorphism.

RESULTS

The incidence of heterochromatin polymorphism was higher in infertile men. The most frequent chromosome involved in heterochromatin polymorphism was chromosome 9. Sperm FISH analysis revealed an increased rate of aneuploidy in men with heterochromatin polymorphism. Laboratory and clinical outcomes in assisted reproductive techniques were compromised in men with heterochromatin polymorphism.

CONCLUSIONS

An increased rate of heterochromatin polymorphism in infertile males seems to be more than an incidental finding, and must not be considered as a normal variant. Polymorphic heterochromatin may have deleterious effects on the genetic constitution of spermatozoa. More attention must be directed to infertile men with heterochromatin polymorphism.

Somatic chromosomal abnormalities in infertile men and women

Infertility--the inability to achieve conception or sustain a pregnancy through to live birth--is very common and affects about 15% of couples. While chromosomal or genetic abnormalities associated with azoospermia, severe oligozoospermia or primary ovarian failure were of no importance for reproduction prior to the era of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), advances in assisted reproductive techniques (ART) now enable many infertile couples to have children. These developments have raised the question of the genetic consequences of ICSI: concerns of the potential harm of the invasive procedure and concerns about the genetic risk. The infertile male and female definitely have an increased risk to carry a chromosomal abnormality. Detection of such an abnormality is of fundamental importance for the diagnosis of infertility, the following treatment, the evaluation of the risk for the future child and the appropriate management of the pregnancy to be obtained. Therefore, cytogenetic screening of both partners is mandatory prior to any type of ART. The present review is based on several surveys on male and female infertility and analyzes the types and frequencies of the different reported chromosome abnormalities according to the type of impairment of spermatogenesis and the type of treatment planned or performed. With regard to assisted reproductive techniques (especially ICSI) the main types of chromosomal abnormalities are discussed and their potential risks for ICSI. If available, reported cases of performed ICSI and its outcome are presented. The detection of an abnormal karyotype should lead to comprehensive genetic counselling, which should include all well-known information about the individual type of anomaly, its clinical relevance, its possible inheritance, the genetic risk of unbalanced offspring, and the possibilities of prenatal diagnosis. Only this proceeding allows at-risk couples to make an informed decision regarding whether or not to proceed with ART. These decisions can be made only when both partners have clearly understood the genetic risks and possible consequences when ART is used.

[Usefulness and necessity of the andrologist in assisted reproductions units]

In this issue we make a review of our experience in the management of the sterile men: protocols used for the study of men's sterility, causes and specific treatments, surgical recovery of spermatozoa and screening before IVF or IVF-ICSI. We concluded that with an adequate protocol, it's possible to establish the aetiology of men's infertility in a 78.8% of the cases and it's also possible to initiate a specific treatment in almost a 47.8% of men. Results of specific treatment, with a previous selection of patients, could be better than those of assisted reproduction techniques. Best results are obtained in cases of vaso-vasostomy (vasectomy reversal) and obstruction of ejaculatory duct. It's also needed a study of genetics causes and bad prognostic circumstances in those men whose partner is going on with an IVF or IVF-ICSI cycle.