Mosaic status in lymphocytes of infertile men with or without Klinefelter syndrome

Detection of low-grade mosaicism and its correlation with hormonal profile, testicular volume, and semen quality in a cohort of Egyptian Klinefelter and Klinefelter-like patients

Klinefelter syndrome (KS) is the most common chromosomal syndrome, causing infertility in men and leading to non-obstructive azoospermia. Previous studies on mosaicism have shown contradictory results on its correlation with both serum hormone levels and the presence of spermatozoa in the ejaculate of KS, KS-like, and non-KS-like infertile patients. So, the present study was designed to detect low-grade mosaicism in the peripheral blood lymphocytes and buccal mucosa cells of 14 KS and 8 KS-like patients by using fluorescence in situ hybridization (FISH) and to investigate its correlation with luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone (T) levels, testicular volume, and semen analysis compared with 10 normal healthy fertile men. Our results indicated that mosaicism was only found in 42.9 % of the KS patients and completely absent in all KS-like patients. Moreover, mosaicism has led to complete azoospermia and non-significant differences in both hormone levels and testicular volume between mosaic and non-mosaic KS patients. All KS patients demonstrated significant differences in both hormone levels and testicular volume compared with normal men. Conversely, they revealed non-significant differences in hormone levels and significant differences in testicular volume compared with KS-like patients. Additionally, the KS-like patients exhibited non-significant variations in both LH and FSH levels and significant variations in T level and testicular volume compared with normal men. Moreover, all KS-like patients had azoospermia, except for one patient who showed oligozoospermia. Therefore, no correlations were found either between mosaicism and serum hormone levels or with testicular volume and semen analysis.

A survey of undetected, clinically relevant chromosome abnormalities when replacing postnatal karyotyping by Whole Genome Sequencing

Whole genome sequencing (WGS) holds the potential to identify pathogenic gene mutations, copy number variation, uniparental disomy and structural rearrangements in a single genetic test. With its high diagnostic yield and decreasing costs, the question arises whether WGS can serve as a single test for all referrals to diagnostic genome laboratories ("one test fits all"). Here, we provide an estimate for the proportion of clinically relevant aberrations identified by light microscopy in postnatal referrals that would go undetected by WGS. To this end, we compiled the clinically relevant abnormal findings for each of the different referral categories in our laboratory during the period 2006-2015. We assumed that WGS would be performed on 300-500 bp DNA fragments with 150-bp paired sequence reads, and that the mean genome coverage is 30x, corresponding to current practice. For the detection of chromosomal mosaicism we set minimum thresholds of 10% for monosomy and 20% for trisomy. Based on the literature we assumed that balanced Robertsonian translocations and ∼9% of other, balanced chromosome rearrangements would not be detectable because of breakpoints in sequences of repetitive DNA. Based on our analysis of all 14,957 referrals, including 1455 abnormal cases, we show that at least 8.1% of these abnormalities would escape detection (corresponding to 0.79% of all referrals). The highest rate occurs in referrals of premature ovarian failure, as 73.3% of abnormalities would not be identified because of the frequent occurrence of low-level sex chromosome mosaicism. Among referrals of recurrent miscarriage, 25.6% of abnormalities would go undetected, mainly because of a high proportion of balanced Robertsonian translocations. In referrals of mental retardation (with or without multiple congenital anomalies) the abnormality would be missed in only 0.35% of referrals. These include cases without imbalances of unique DNA sequences but of clinical relevance, as for example, r(20) epilepsy syndrome. The expected shift to large-scale implementation of WGS ("one test fits most") as initial genetic test will be beneficial to patients and their families, since a cause for the clinical phenotype can be identified in more cases by a single genetic test at an early phase in the diagnostic process. However, a niche for genome analysis by light microscopy will remain. For example, in referrals of newborns with a suspicion of Down syndrome, karyotyping is not only a cost-effective method for providing a quick diagnosis, but also discriminates between trisomy 21 and a Robertsonian translocation involving chromosome 21. Thus, when replacing karyotyping by WGS, one must be aware of the rates and spectra of undetected abnormalities. In addition, it is equally important that requirements for cytogenetic follow-up studies are recognized.

Genetic diagnostics of male infertility in clinical practice

Approximately 15% of couples are infertile. Male factors contribute to infertility in over 50% of cases. Identifiable genetic abnormalities contribute to 15%-20% of the most severe forms of male infertility, azoospermia. In this chapter, we explore known genetic causes of male infertility such as Klinefelter syndrome, XYY men, Kallmann syndrome, y-microdeletions, Robertsonian translocations, autosomal inversions, mixed gonadal dysgenesis, x-linked and autosomal gene mutations, and cystic fibrosis transmembrane conductance regulator abnormalities. We also briefly comment on novel biomarkers for male infertility.

Mutational landscape of the human Y chromosome-linked genes and loci in patients with hypogonadism

Sex chromosome-related anomalies engender plethora of conditions leading to male infertility. Hypogonadotropic hypogonadism (HH) is a rare but well-known cause of male infertility. Present study was conducted to ascertain possible consensus on the alterations of the Y-linked genes and loci in males representing hypogonadism (H), which in turn culminate in reproductive dysfunction. A total of nineteen 46, XY males, clinically diagnosed with H (11 representative HH adults and eight prepubertal boys suspected of having HH) were included in the study. Sequence-tagged site screening,SRY gene sequencing,fluorescence in situ hybridization mapping (FISH), copy number and relative expression studies by real-time PCR were conducted to uncover the altered status of the Y chromosome in the patients. The result showed random microdeletions within the AZFa (73%)/b (78%) and c(26%) regions. Sequencing of the SRY gene showed nucleotide variations within and outside of the HMG box in four males (21%). FISH uncovered mosaicism for SRY, AMELY,DAZ genes and DYZ1 arrays, structural rearrangement for AMELY (31%) and duplication of DAZ (57%) genes. Copy number variation for seven Y-linked genes (2-8 rounds of duplication), DYZ1 arrays (495-6201 copies) and differential expression of SRY,UTY and VCY in the patients' blood were observed. Present work demonstrates the organizational vulnerability of several Y-linked genes in H males. These results are envisaged to be useful during routine diagnosis of H patients.

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.

Discordant sex in monozygotic XXY/XX twins: a case report

We report a case of discordant phenotypic sex in monozygotic twins mosaic 47,XXY/46,XX: monozygotic heterokaryotypic twins. The twins presented with cognitive and comprehension delay, behavioural and language disorders, all symptoms frequently reported in Klinefelter syndrome. Molecular zygosity analysis with several markers confirmed that the twins are in effect monozygotic (MZ). Array comparative genomic hybridization found no evidence for the implication of copy number variation in the phenotypes. Ultrasound scans of the reproductive organs revealed no abnormalities. Endocrine tests showed a low testosterone level in Twin 1 (male phenotype) and a low gonadotrophin level in Twin 2 (female phenotype) which, combined with the results from ultrasound examination, provided useful information for potentially predicting the future fertility potential of the twins. Blood karyotypes revealed the presence of a normal 46,XX cell line and an aneuploïd 47,XXY cell line in both patients. Examination of the chromosome constitutions of various tissues such as blood, buccal smear and urinary sediment not surprisingly showed different proportions for the 46,XX and 47,XXY cell lines, which most likely explains the discordant phenotypic sex and mild Klinefelter features. The most plausible underlying biological mechanism is a post-zygotic loss of the Y chromosome in an initially 47,XXY zygote. This would result in an embryo with both 46,XX and 47,XXY cells lines which could subsequently divide into two monozygotic embryos through a twinning process. The two cell lines would then be distributed differently between tissues which could result in phenotypic discordances in the twins. These observations emphasize the importance of regular paediatric evaluations to determine the optimal timing for fertility preservation measures and to detect new Klinefelter features which could appear throughout childhood in the two subjects.

Management of Klinefelter syndrome during transition

Klinefelter syndrome (KS) is the most common sex chromosomal disorder in males. Key findings in older adolescents and young men are small testes with variable hypo-androgenism, but almost universal azoospermia, most frequently in combination with a history of learning difficulties and behavior problems. Males with KS may come to medical attention through different medical presentations, given its association with several congenital malformations, and psychiatric, endocrine, and metabolic disorders. Preventive care is to be provided from diagnosis, preferentially through a multidisciplinary approach, including that from an endocrinologist, clinical psychologist or psychiatrist, neurologist, urologist, geneticist, sexologist, and a fertility team. Accurate information about the condition and assessment of associated medical conditions should be offered at diagnosis and should be followed by psychological counseling. Medical treatment during transition into adulthood is focused on fertility preservation and testosterone replacement therapy in the case of hypo-androgenism, and alleviation of current or future consequences of testicular fibrosis. However, more research is needed to determine the need for pro-active testosterone treatment in adolescence, as well as the conditions for an optimal testosterone replacement and sperm retrieval in adolescents and young men with KS. Furthermore, screening for associated diseases such as metabolic syndrome, autoimmune diseases, thyroid dysfunction, and malignancies is warranted during this period of life. The practical medical management during transition and, more specifically, the role of the endocrinologist are discussed in this article.

Role of optimizing testosterone before microdissection testicular sperm extraction in men with nonobstructive azoospermia

PURPOSE

Although optimizing endogenous testosterone production before testicular sperm extraction is commonly practiced, whether improved preoperative testosterone levels enhance sperm retrieval remains unclear. We evaluated the influence of preoperative medical therapy in men with nonobstructive azoospermia before microdissection testicular sperm extraction.

MATERIALS AND METHODS

A total of 1,054 men underwent microdissection testicular sperm extraction from 1999 to 2010. Patients with preoperative testosterone levels less than 300 ng/dl were treated with aromatase inhibitors, clomiphene citrate or human chorionic gonadotropin before microdissection testicular sperm extraction with the goal of optimizing testosterone levels. Patient demographics, preoperative testosterone levels, sperm retrieval rate and pregnancy outcomes were recorded and compared in men with different baseline testosterone levels.

RESULTS

Of the 736 men who had preoperative hormonal data 388 (53%) had baseline testosterone levels greater than 300 ng/dl. The sperm retrieval rate in these men was 56%. In the remaining 348 men with pretreatment testosterone levels less than 300 ng/dl, the sperm retrieval rate was similar (52%, p = 0.29). In addition, the sperm retrieval, clinical pregnancy and live birth rates were similar between men who responded to hormonal therapy and those who did not.

CONCLUSIONS

Men with nonobstructive azoospermia and hypogonadism often respond to hormonal therapy with an increase in testosterone levels, but neither baseline testosterone level nor response to hormonal therapy appears to affect overall sperm retrieval, clinical pregnancy or live birth rates.

Hidden mosaicism in patients with Klinefelter's syndrome: implications for genetic reproductive counselling

BACKGROUND

Most individuals with Klinefelter's syndrome (KS) are azoospermic but residual foci of spermatogenesis have been observed in some patients. However, no consistent predictive factors for testicular sperm extraction success have been established and mosaicism could be a factor to investigate. In this study, we have assessed the degree of mosaicism in somatic and germinal tissues in KS, the meiotic competence of 47,XXY germ cells and the aneuploidy rate of post-reductional cells.

METHODS

Five patients with KS previously diagnosed as pure 47,XXY have been studied. Samples from four donors were processed as controls. The chromosome constitution of lymphocytes, buccal mucosa and testicular tissue was assessed by interphase fluorescence in situ hybridization for chromosomes X, Y and 18. In meiotic figures, sex chromosome number and pairing was confirmed.

RESULTS

46,XY cell lines were observed in all patients and tissues analysed. The degree of mosaicism (mean ± SD) differed among tissues (lowest in lymphocytes: 4.8 ± 2.5%; highest in Sertoli cells: 42.3 ± 11.1%). Meiotic figures were found in three cases (KS1, KS2 and KS5), all of them showed an XY complement. Hyperhaploid post-reductional cells were found in all patients (range: 3.3-36.4%) and increased rates versus controls (P< 0.05) were observed.

CONCLUSIONS

Diagnosis of homogeneous KS based on lymphocyte karyotyping should be contrasted in other tissues. Mucosa cells could help to better approximate the degree of germ cell mosaicism. Our results indicate that 47,XXY germ cells are not meiotically competent. Increased post-reductional aneuploidy rate is related to meiotic errors in 46,XY cells. Appropriate genetic counselling is recommended in KS.

[Fertility in patients with Klinefelter syndrome (47,XXY)]

In the past 10 years, our knowledge about fertility chances of patients with Klinefelter syndrome (KS, 47,XXY) has changed considerably, especially when regarding the possibility of IVF ICSI treatment (in vitro fertilisation, intracytoplasmic sperm injection) with single testicular spermatozoa. Thus, it is important to take this knowledge into consideration when counselling Klinefelter patients.Germ cell degeneration in the testicles of Klinefelter patients due to their additional X chromosome is an important phenomenon in this disease which is not yet fully understood. When entering puberty, the testicular volume of KS patients increases for a short time with rising testosterone and inhibin B levels at the same time. These decrease, however, and FSH increases during puberty. This seems to indicate a critical point in time when spermatogenetic function of the testicles could still be existent. Thus, in early puberty there could possibly be a time slot when spermatozoa could be detected in the ejaculate or-if not-at least in the testicular tissue. These could be extracted by testicular sperm extraction, cryopreserved and used for intracytoplasmic sperm injection therapy later on. In the literature, a total of 133 births of children from Klinefelter fathers have been reported. This early specific procedure could lead to a better acceptance of their diagnosis and also offer the option of not being incurably infertile.

Use of DOP-PCR for amplification and labeling of BAC DNA for FISH

Fluorescence in situ hybridization (FISH) is a powerful molecular cytogenetic method that permits rapid detection of specific chromosomal rearrangements. It is based on the hybridization of fluorescent labeled probes to metaphase chromosomes or interphase nuclei. The DNA probes commonly are generated from cloned sources such as bacterial artificial chromosomes (BACs). The major disadvantage of this approach is that it requires laborious and time-consuming work. We used a degenerate oligonucleotide primed polymerase chain reaction (DOP-PCR) for both amplification and labeling of very small amounts of purified BAC DNA for FISH. The DOP-PCR reaction was processed in two steps: pre-amplification followed by simultaneous amplification and labeling of BAC DNA. The DOP-PCR probes obtained provided good hybridization signals and low background. Thus, DOP-PCR can be used to produce unlimited quantities of FISH probes with decreased cost and labor.

Male 41, XXY* mice as a model for klinefelter syndrome: hyperactivation of leydig cells

Sex chromosome imbalance in males is linked to a supernumerary X chromosome, a condition resulting in Klinefelter syndrome (KS; 47, XXY). KS patients suffer from infertility, hypergonadotropic hypogonadism, and cognitive impairments. Mechanisms of KS pathophysiology are poorly understood and require further exploration using animal models. Therefore, we phenotypically characterized 41, XX(Y)* mice of different ages, evaluated observed germ cell loss, studied X-inactivation, and focused on the previously postulated impaired Leydig cell maturation and function as a possible cause of the underandrogenization seen in KS. Xist methylation analysis revealed normal X-chromosome inactivation similar to that seen in females. Germ cell loss was found to be complete and to occur during the peripubertal phase. Significantly elevated FSH and LH levels were persistent in 41, XX(Y)* mice of different ages. Although Leydig cell hyperplasia was prominent, isolated XX(Y)* Leydig cells showed a mature mRNA expression profile and a significantly higher transcriptional activity compared with controls. Stimulation of XX(Y)* Leydig cells in vitro by human chorionic gonadotropin indicated a mature LH receptor whose maximal response exceeded that of control Leydig cells. The hyperactivity of Leydig cells seen in XX(Y)* mice suggests that the changes in the endocrine milieu observed in KS is not due to impaired Leydig cell function. We suggest that the embedding of Leydig cells into the changed testicular environment in 41 XX(Y)* males as such influences their endocrine function.

Fertility in a i(Xq) Klinefelter patient: importance of XIST expression level determined by qRT-PCR in ruling out Klinefelter cryptic mosaicism as cause of oligozoospermia

The presence of an isochromosome Xq in Klinefelter syndrome (KS) is an apparently rare condition. In all cases reported so far, patients showed the classic phenotype. We here describe a case of isochromosome Xq [47,X,i(Xq),Y] in a non-mosaic KS patient. The patient exhibited a normal androgenized phenotype, normal testes and normal cognitive abilities. Semen analysis revealed a medium oligozoospermia (5 x 10(6) spermatozoa/ml). After the patient underwent intracytoplasmic sperm injection, he generated two cytogenetically healthy normal females. Fluorescence in situ hybridization analysis showed the presence of a dicentric Xq chromosome that did not show the presence of residual Xp arm up to the 57,820,478 bp position (Xp 1.1) of X chromosome sequence. Preferential inactivation of Xq isochromosome was demonstrated by bromodeoxyuridine replication analysis and transcriptional silencing by DNA methylation at the HUMARA locus. Furthermore, we demonstrated by quantitative RT-PCR an active XIST RNA expression in blood lymphocytes from Klinefelter patients, comparable to that observed in control females and over 30,000-fold greater than in control males. In conclusion, this qRT-PCR approach could be useful for screening of prepuberty males and for diagnosis or exclusion of cryptic Klinefelter mosaics.

Rare XXY/XX mosaicism in a phenotypic male with Klinefelter syndrome: case report

Klinefelter syndrome represents the most commonly found human sex chromosomal abnormality. It is characterized by small, firm testes with hyalinization of the seminiferous tubules, elevated gonadotropins and azoospermia. Males with Klinefelter syndrome may have a 47,XXY or a mosaic 47,XXY/46,XY constitutional karyotype and varying degrees of spermatogenic failure. Mosaicism 47,XXY/46,XX with clinical features suggestive of Klinefelter syndrome, is very rare and so far only 10 cases have been described in literature [1,2,5,8,10,15,22,23,25,44]. We report here a case of a mosaic 47,XXY/46,XX infertile male in whom detailed cytogenetic, histological and molecular studies were performed. Cytogenetic analysis revealed 80% and 50% mosaicism for the 46,XX cell line in blood lymphocytes and in skin fibroblasts, respectively, and the presence of 47,XXY cells only, in cultured testicular tissue. Testicular histopathology revealed atrophy of the testes with no spermatogenesis and absence of germ cells. Molecular analysis showed paternal inheritance of the extra X chromosome.

Y chromosome microdeletions in azoospermic patients with Klinefelter's syndrome

AIM

To study the occurrence of Y chromosome microdeletions in azoospermic patients with Klinefelter's syndrome (KFS).

METHODS

Blood and semen samples were collected from azoospermic patients with KFS (n = 14) and a control group of men of proven fertility (n = 13). Semen analysis was done according to World Health Organization (WHO) guidelines. Blood samples were processed for karyotyping, fluorescent in situ hybridization (FISH) and measurement of plasma follicle stimulating hormone (FSH) by radioimmunoassay. To determine Y chromosome microdeletions, polymerase chain reaction (PCR) of 16 sequence tagged sites (STS) and three genes (DFFRY, XKRY and RBM1Y) was performed on isolated genomic DNA. Testicular fine needle aspiration cytology (FNAC) was done in selected cases.

RESULTS

Y chromosome microdeletions spanning the azoospermia factor (AZF)a and AZFb loci were found in four of the 14 azoospermic patients with KFS. Karyotype and FISH analysis revealed that, of the four cases showing Y chromosome microdeletion, three cases had a 47,XXY/46,XY chromosomal pattern and one case had a 46,XY/47,XXY/48,XXXY/48,XXYY chromosomal pattern. The testicular FNAC of one sample with Y chromosome microdeletion revealed Sertoli cell-only type of morphology. However, no Y chromosome microdeletions were observed in any of the 13 fertile men. All patients with KFS had elevated plasma FSH levels.

CONCLUSION

Patients with KFS may harbor Y chromosome microdeletions and screening for these should be a part of their diagnostic work-up, particularly in those considering assisted reproductive techniques.

Natural history of seminiferous tubule degeneration in Klinefelter syndrome

Klinefelter syndrome (47,XXY) is characterized by small, firm testis, gynaecomastia, azoospermia and hypergonadotropic hypogonadism. Degeneration of the seminiferous tubules in 47,XXY males is a well-described phenomenon. It begins in the fetus, progresses through infancy and accelerates dramatically at the time of puberty with complete hyalinization of the seminiferous tubules, although a few tubules with spermatogenesis may be present in adult life. Activation of the pituitary-gonadal axis at 3 months of age is seen in Klinefelter boys similar to healthy boys. However, the level of testosterone in Klinefelter boys is significantly lower than in controls. After this 'minipuberty', the hormone levels decline to normal prepubertal levels until puberty. In puberty, an initial rise in testosterone, inhibin B, LH and FSH occurs in Klinefelter boys. However, the rise in testosterone levels off and ends at a low-normal level in young adults. Likewise, serum concentration of inhibin B exhibits a dramatic decline to a low, often undetectable level, concomitantly with a rise in FSH, reflecting the degeneration of the seminiferous tubules. Many hypotheses about the underlying mechanism of the depletion of the germ cells in Klinefelter males have been reported and include insufficient supranumerary X-chromosome inactivation, Leydig cell insufficiency and disturbed regulation of apoptosis of Sertoli and Leydig cells. However, at present, the exact mechanism remains unclear. In this article, we summarize current knowledge on the development of the classical endocrinological and histological features of 47,XXY males from fetus to adulthood and review the literature concerning the degeneration of the seminiferous tubules in this syndrome.