Natural history of seminiferous tubule degeneration in Klinefelter syndrome

Low semen volume in 47 adolescents and adults with 47,XXY Klinefelter or 46,XX male syndrome

Klinefelter syndrome is characterized by progressive testicular failure causing androgen deficiency and azoospermia in most patients. The aim of this study was to evaluate semen quality in consecutive patients with an additional X chromosome as compared with healthy males. Forty-seven males with non-mosaic 47,XXY (n = 40) or SRY-positive 46,XX male (n = 7) karyotypes aged 26.1 (range: 15.0-51.7) years participated. Semen quality was compared with 2136 (control group I) men from the general population aged 18.9 (17.9-28.6) years and with 349 fertile men (control group II) aged 30.9 (22.0-43.8) years. Semen volume adjusted for duration of abstinence was significantly smaller in the patients [2.0 (0.2-5.7) mL] when compared with control group I [3.1 (0.3-12.5) mL, p < 0.0001] and group II [3.6 (0.6-12.5) mL, p < 0.0001]. There was no difference in semen volume between 47,XXY and 46,XX males. All patients had azoospermia except two 47,XXY males aged 29 years who had sperm concentrations of 0.5 and 1.6 million/mL, respectively. We found significantly smaller semen volume in the patients when compared with controls, and the presence of motile spermatozoa in two out of 47 patients. The small semen volume supports the notion of 47,XXY patients being androgen insufficient despite serum testosterone levels within the normal range.

Phenotype manifestations of polysomy X at males

Klinefelter Syndrome is the most frequent form of male hypogonadism. It is an endocrine disorder based on sex chromosome aneuploidy. Infertility and gynaecomastia are the two most common symptoms that lead to diagnosis. Diagnosis of Klinefelter syndrome is made by karyotyping. Over 20 years period (1985-2004) 124 patients have been sent to "Center for Human Genetics" of Faculty of Medicine in Sarajevo from different medical centres within Federation of Bosnia and Herzegovina with diagnosis suspecta Klinefelter syndrome, azoospermia, sterilitas primaria and hypogonadism for cytogenetic evaluation. Normal karyotype was found in 99 (79.8%) subjects, and karyotype was changed in 25 (20.2%) subjects. Polysomy X was found in 14 (11.3%) examinees. Polysomy X was expressed at the age of sexual maturity in the majority of the cases. Our results suggest that indication for chromosomal evaluation needs to be established at a very young age.

The genetic basis of male reproductive failure

Evolving therapies have allowed the use of sperm from men with spermatogenic compromise, obstructive azoospermia, and sperm functional deficiency, enabling these men to procreate when unable to do so naturally. The genetic basis of only a portion of these conditions is known and research must be pursued into the genetic underpinnings of those that have not yet been delineated. Education and provision of information to patients is the responsibility of all involved in the care of men with reproductive failure. The author concentrates on some of the known causes of nonobstructive azoospermia and obstructive azoospermia with a well-established genetic cause such as congenital bilateral absence of the vas deferens.

Increased basal and pulsatile secretion of FSH and LH in young men with 47,XXY or 46,XX karyotypes

OBJECTIVE

The regulation of normal sexual maturation and reproductive function is dependent on a precise hormonal regulation at hypothalamic, pituitary, and gonadal levels. The aim of this study was to investigate the neuroendocrine integrity of the pituitary-gonadal axis in patients with primary testicular failure due to supernumerary X chromosomes.

DESIGN

Cross-sectional study.

METHODS

In this study, 7 untreated patients with primary gonadal insufficiency due to SRY-positive 46,XX (n=4) and 46,XXY karyotypes (n=3) aged 18.8 years and 25 age-matched healthy controls participated. Reproductive hormones, testicular size, and overnight LH and FSH serum profiles and overnight urine LH and FSH excretion were determined.

RESULTS

Basal LH and FSH secretion was elevated 6.3- and 25.4-fold respectively in the patients and the amount of LH and FSH secreted per burst were 2.0- and 6.6-fold elevated. We found significantly more LH but not FSH peaks per 24 h, as estimated by the Weibull lambda analysis. There was no difference between approximate entropy ratios or Weibull gamma analyses indicating comparable orderliness and regularity of LH and FSH secretion. Overnight urinary LH and FSH excretion was significantly elevated in patients compared with controls and correlated significantly with calculated total overnight LH and FSH secretion respectively, thus validating deconvolution.

CONCLUSION

In this group of patients with severe hypergonadotropic hypogonadism due to a supernumerary X chromosome, higher basal, pulsatile, and total LH and FSH secretion were associated with significantly more LH peaks per 24 h in comparison with healthy controls. Thus, our data indicate that in patients with Klinefelter syndrome and XX male karyotypes the entire hypothalamic-pituitary-gonadal axis has undergone functional changes.

Effect of ascertainment and genetic features on the phenotype of Klinefelter syndrome

OBJECTIVE

To describe the Klinefelter Syndrome (KS) phenotype during childhood in a large cohort.

STUDY DESIGN

Clinical assessment, measurement of hormonal indices of testicular function, and parent of origin of extra X chromosome were assessed in a cross-sectional study of 55 boys with KS, aged 2.0 to 14.6 years, at an outpatient center.

RESULTS

Mean height and body mass index SD scores (SDS +/- SD) were 0.9 +/- 1.3 and 0.4 +/- 1.4, respectively. Mean penile length and testicular volume SDS were -0.5 +/- 0.9 and -0.9 +/- 1.4. Testosterone levels were in the lowest quartile of normal in 66% of the cohort. Other features included clinodactyly (74%), hypertelorism (69%), elbow dysplasia (36%), high-arched palate (37%), hypotonia (76%), and requirement for speech therapy (69%). Features were similar in boys in whom the diagnosis was made prenatally versus boys in whom the diagnosis was made postnatally. There was no evidence for a phenotypic effect of parent of origin of the extra X chromosome.

CONCLUSIONS

Boys with KS commonly have reduced penile length and small testes in childhood. The phenotype in boys with KS does not differ according to ascertainment or origin of the extra X chromosome. Boys with KS may be identified before puberty by tall stature, relatively decreased penile length, clinodactyly, hypotonia, and requirement for speech therapy.

Abnormal sex chromosome constitution and longitudinal growth: serum levels of insulin-like growth factor (IGF)-I, IGF binding protein-3, luteinizing hormone, and testosterone in 109 males with 47,XXY, 47,XYY, or sex-determining region of the Y chromosome (SRY)-positive 46,XX karyotypes

CONTEXT

Growth is a highly complex process regulated by the interaction between sex steroids and the GH IGF-axis. However, other factors such as sex chromosome-related genes play independent roles.

AIM

The aim of the study was to evaluate the role of abnormal chromosome constitution for longitudinal growth in relation to reproductive hormones, IGF-I, and IGF binding protein (IGFBP)-3.

SETTING

The study was conducted at an outpatient clinic, Copenhagen University Hospital.

PARTICIPANTS

Participants included 86 47,XXY males, 14 46,XX-males, and nine 47,XYY.

MAIN OUTCOME MEASURES

Standing and sitting height, serum levels of reproductive hormones, IGF-I, and IGFBP-3 were measured.

RESULTS

In boys with 47,XXY and 47,XYY karyotypes, growth was accelerated already in childhood, compared with healthy boys. 46,XX-males were significantly shorter than healthy boys but matched the stature of healthy girls. In 47,XXY sitting height to height ratios were lower than expected, whereas body proportions in 46,XX-males and 47,XYY were normal. In all subjects serum levels of IGF-I and IGFBP-3 were within normal limits. The boys with 46,XX and 47,XXY karyotypes presented with low normal testosterone and elevated LH levels after puberty, whereas the sex hormone secretion of the 47,XYY boys remained normal.

CONCLUSION

We found accelerated growth in early childhood in boys with 47,XXY and 47,XYY karyotypes, whereas 46,XX-males were shorter than controls. These abnormal growth patterns were not reflected in circulating levels of IGF-I and IGFBP-3. The boys with 46,XX and 47,XXY karyotypes developed hypogonadism in puberty, but androgen secretion in 47,XYY boys remained normal. The abnormal stature of these patients may be a result of abnormal gene expression due to the underlying chromosome aberration resulting in excessive expression of growth-related genes.

Update in andrology

CONTEXT

This is an invited review based on a presentation at the 2007 Annual Scientific Meeting of The Endocrine Society.

OBJECTIVE

The objective of the review was to highlight a selection of the most important peer-reviewed papers in andrology published over the last 1-2 yr.

EVIDENCE ACQUISITION

This was a comprehensive survey of all papers published in major endocrinology journals over the last 2 yr augmented by personal knowledge and literature searching as well as an e-mail survey of more than 40 leading andrologists.

EVIDENCE SYNTHESIS

From the list of suggested papers, the findings of a short list considered the most important were reviewed, aiming to focus on findings that influence thinking and practice in the field of andrology.

CONCLUSIONS

Important advances highlighted included establishing genetic paternity for men with Klinefelter's syndrome as a realistic therapeutic option via testicular sperm aspiration coupled with intracytoplasmic sperm injection in vitro fertilization, using population registry linkage data to define the natural history of Klinefelter's syndrome in the community and identifying active cellular uptake mechanisms for SHBG-bound testosterone challenging the quasiaxiomatic status of the free hormone hypothesis. Other important recent contributions reviewed are on testosterone effects on the prostate, hormonal male contraception, possible temporal trends in blood testosterone concentrations in American men, and The Endocrine Society's position papers on testosterone assays and guidelines on testosterone prescribing.

Establishment of testicular endocrine function impairment during childhood and puberty in boys with Klinefelter syndrome

OBJECTIVE

To precisely characterize the chronology of testicular endocrine function impairment during childhood and adolescence in patients with Klinefelter syndrome. Design Retrospective chart review. Patients A total of 29 boys with Klinefelter syndrome with up to 12.3 years follow-up.

MEASUREMENTS

Clinical features and serum hormone levels were analysed during follow-up.

RESULTS

Of the 29 patients, 16 were prepubertal and 13 had already entered puberty at their first visit. Fifteen patients were followed up through late puberty. Before puberty, LH, FSH, testosterone, anti-Müllerian hormone (AMH) and inhibin B were within the expected range in almost all cases. However, levels of the inhibin alpha-subunit precursor Pro-alphaC were in the lowest levels of the normal range in most cases. During puberty, FSH levels increased earlier and more markedly than LH. Inhibin B and AMH declined to abnormally low or undetectable levels in advanced pubertal stages. Although testosterone and Pro-alphaC levels were within the reference ranges in most cases, they were abnormally low for the observed LH values.

CONCLUSIONS

In Klinefelter syndrome, a mild Leydig cell dysfunction is present from early childhood in most cases and persists throughout puberty. Sertoli cell function is normal until mid puberty, when a dramatic impairment is observed.

Why human extragonadal germ cell tumours occur in the midline of the body: old concepts, new perspectives

Hypotheses on the origin and distribution of extragonadal germ cell tumours (GCTs) and teratomas are briefly reviewed and revisited in the light of (i) new developments in the classification of GCTs, (ii) data on genomic imprinting of these neoplasms and (iii) the recent finding that germ cells can be derived from mouse and human embryonal stem (ES) cells. Only the Type I (infantile teratomas/yolk sac tumours) and Type II GCTs (seminomatous tumours and non-seminomas) occur in the gonads and extragonadal localizations. The data on genomic imprinting lend support to the hypothesis that they are derived from germ cells. These precursor cells could have differentiated from ES cells in extragonadal localizations. Their distribution along the midline of the body is still best explained by the migration of primitive germ cells during development. The narrower distribution of the Type II than the Type I GCTs is probably due to the more strict conditions for survival and proliferation of primordial germ cells (PGCs)/gonocytes from which the Type II tumours originate, when compared with the precursor cells of Type I tumours, probably primitive germ cells closer to the ES cell. The known niches in which the Type II tumours develop have in common that they contain feeder cells expressing stem cell factor (SCF) - the ligand for the SCF receptor c-KIT, involved in proliferation and survival of PGCs/gonocytes - and contain GBY including the gene TSPY.

Tumor risk in disorders of sex development (DSD)

Disorders of sex development (DSD), previously referred to as intersex disorders, comprise a variety of anomalies defined by congenital conditions in which chromosomal, gonadal, or anatomical sex is atypical. Besides issues such as gender assignment, clinical and diagnostic evaluation, surgical and psychosocial management, and sex steroid replacement, the significantly increased risk for developing specific types of malignancies is both clinically and biologically relevant. This relates to germ-cell tumors specifically in DSD patients with hypovirilization or gonadal dysgenesis. The presence of a well-defined part of the Y chromosome (known as the GBY region) is a prerequisite for malignant transformation, for which the testis-specific protein on the Y chromosome (TSPY) is a likely candidate gene. The precursor lesions of these cancers are carcinoma in situ (CIS)/intratubular germ-cell neoplasia unclassified (ITGCNU) in testicular tissue and gonadoblastoma in those without obvious testicular differentiation. Most recently, undifferentiated gonadal tissue (UGT) has been identified as the likely precursor for gonadoblastoma. The availability of markers for the different developmental stages of germ cells allows detailed investigation of the characteristics of normal and (pre)malignant germ cells. Although informative in a diagnostic setting for adult male patients, these markers - such as OCT3/4 - cannot easily distinguish (pre)malignant germ cells from germ cells showing delayed maturation. This latter phenomenon is frequently found in gonads of DSD patients, and may be related to the risk of malignant transformation. Thus, the mere application of these markers might result in over-diagnosis and unnecessary gonadectomy. It is proposed that morphological and histological evaluation of gonadal tissue, in combination with OCT3/4 and TSPY double immunohistochemistry and clinical parameters, is most informative in estimating the risk for germ-cell tumor development in the individual patient, and might in future be used to develop a decision tree for optimal management of patients with DSD.

Neoplasms and pathology of sexual developmental disorders (intersex)

Continuing new insights into the biology of sexual development and advances in chromosome analysis have led to early identification and prompt treatment of the intersexual patient, the results of which facilitate a more normal life for affected individuals. Based on these advances, a classification of abnormal sexual development has been developed and refined that correlates the gonadal and genital anatomy with the chromosomal findings and specific genetic or metabolic defects. In a shift from a classification anchored on whether the intersex revolves about a specific gene or whole chromosomal abnormality, the current classification is organised by broader categories into which the intersexual disorders are divided into 'abnormalities of genital differentiation', due largely to the abnormal production or sensitivity of a single hormone, or 'abnormalities in sex determination', due to abnormal gonadal differentiation, usually testicular, with or without chromosomal aberration. The current classification is an integrated approach to this complex group of disorders and is organised according to the manner by which patients present as well as on the pathophysiological basis of the defect. The classification also groups patients who are at high risk for development of gonadal neoplasia.

Primary testicular failure in Klinefelter's syndrome: the use of bivariate luteinizing hormone-testosterone reference charts

BACKGROUND

The diagnosis of androgen deficiency is based on clinical features and confirmatory low serum testosterone levels. In early primary testicular failure, a rise in serum LH levels suggests inadequate androgen action for the individual's physiological requirements despite a serum testosterone level within the normal range. The combined evaluation of serum LH and testosterone levels in the evaluation of testicular failure has not been widely advocated.

PATIENTS

Seven hundred and six healthy males and 39 patients with known primary hypogonadism due to Klinefelter's syndrome and SRY-positive 46,XX karyotypes were included in the study.

DESIGN

Testosterone, oestradiol and LH serum concentrations were measured in all individuals. Based on the 706 healthy males two-dimensional bivariate LH-testosterone reference charts were constructed.

RESULTS

Despite a median serum total and free testosterone and oestradiol levels being reduced (P < 0.001) and LH levels elevated (P < 0.001) in Klinefelter's syndrome and 46,XX-males, many subjects (69%) had total testosterone within the reference range. However, using the bivariate charts all subjects lay outside the 97.5 percentile.

CONCLUSION

Bivariate LH and testosterone charts are useful in the evaluation of men with known primary testicular failure due to sex chromosomal aneuploidy in whom evaluation based on testosterone measurement in isolation underestimates the prevalence of hypogonadism. It is, however, important to emphasize that isolated use of the bivariate evaluation should not form the basis for androgen substitution therapy. Further studies are needed in order to evaluate the use of bivariate LH and testosterone charts in the assessment of any younger man with possible primary testicular failure.

Immunoexpression of androgen receptor and nine markers of maturation in the testes of adolescent boys with Klinefelter syndrome: evidence for degeneration of germ cells at the onset of meiosis

CONTEXT

The pathogenesis and mechanisms behind the degeneration of the seminiferous tubules in testes of subjects with Klinefelter syndrome (KS) are yet unknown.

OBJECTIVE

The objective of this prospective clinical study was to characterize the testicular degeneration process during puberty in boys with KS by describing the immunoexpression of some developmentally regulated markers of testis maturation in relation to serum levels of reproductive hormones.

SETTING

This study was conducted at a university central hospital pediatric referral endocrinology outpatient clinic.

PATIENTS

Patients consisted of 14 boys with KS aged 10.1 to 14.0 yr.

MAIN OUTCOME MEASURES

Main outcome measures were immunoexpression of germ cell differentiation markers (AP-2gamma, CHK2, OCT-3/4, NY-ESO-1, MAGE-A4) and androgen action-related proteins [androgen receptor (AR), anti-Müllerian hormone (AMH), MIC2, inhibin B; alpha- and betaB-subunits] in testicular biopsies of boys with KS in relation to serum reproductive hormone levels.

RESULTS

In boys with KS, gonocytes differentiated to the spermatogonium stage, but no spermatocytes were visible. Despite this, down-regulation of AMH expression in the Sertoli cells occurred concomitantly with decreasing serum AMH levels. Expression of inhibin alpha- and betaB-subunits appeared in the biopsies even when circulating inhibin B levels were undetectable. In the boys with KS compared with age-matched controls, the proportion of Sertoli cell nuclei expressing AR was smaller and cytoplasmic staining of Sertoli cells was constantly present.

CONCLUSIONS

We showed with several testis-specific markers in KS that gonocytes differentiate to spermatogonia and that the degeneration of the testes accelerates at the onset of puberty. Altered immunoexpression of AR indicates that a relative androgen deficiency, at least at the testicular level, develops in boys with KS during puberty.

Variant Klinefelter syndrome 47,X,i(X)(q10),Y and normal 46,XY karyotype in monozygotic adult twins

Klinefelter syndrome (KS; 47, XXY) is characterized by increased body height, hypergonadotrophic hypogonadism, and infertility. We describe a patient with a variant KS (47,X,i(Xq),Y) who has a twin brother with a 46,XY karyotype. Molecular studies showed that the twins were monozygotic. The presence of an isochromosome Xq in one of two monozygotic twins allows precise investigation of its phenotypic effect. The patient was somewhat shorter (3.5 cm) and had a smaller volume of the testes (8 vs. 18 ml) as compared to his twin brother. Furthermore he had increased gonadotrophin levels and an extreme oligoasthenoteratozoospermia (OAT). These data support the view that genes on Xp cause increased body height and genes on Xq cause infertility in KS. To our knowledge this is the first report on a heterokaryotypic monozygotic twin with a variant KS.

Genetic features of the X chromosome affect pubertal development and testicular degeneration in adolescent boys with Klinefelter syndrome

OBJECTIVE

To investigate how genetic features of the X chromosome influence growth, pubertal development and testicular degeneration in adolescent boys with Klinefelter syndrome (KS). Previous studies have suggested that genetic features of the X chromosome may contribute to the wide phenotypic variation in KS.

DESIGN

A prospective clinical study.

PATIENTS

Fourteen nonmosaic 47,XXY boys, aged 10-13.9 years.

MEASUREMENTS

The relationship of genetic features of the X chromosome, including parental origin of X chromosomes, the CAG repeat length of the androgen receptor (AR) gene, and X inactivation with progression of pubertal development, growth and testicular function in KS boys.

RESULTS

Paternal (47,XmXpY, n = 3) as compared to maternal (47,XmXmY, n = 11) origin of the supernumerary X chromosome was associated with a later onset of puberty. In 47,XmXpY patients, serum LH concentrations increased above 1.0 IU/l at 12.5 +/- 0.6 years (mean +/- SD), Tanner stage P2 occurred at 12.5 +/- 0.7 years, and pubertal acceleration of growth was noted at 13.9 +/- 1.4 years and peak velocity at 14.5 +/- 0.8 years. All of these occurred 1.3-1.9 years later than in 47,XmXmY patients (P = 0.01-0.09). In 47,XmXmY subjects, CAG repeat length (range 17-26) correlated with age at which serum LH level first exceeded 1.0 IU/l (rs = 0.63, P = 0.06, n = 10) and testosterone 1.0 nmol/l (28.8 ng/dl) (rs = 0.78, P = 0.02, n = 10).

CONCLUSIONS

Paternal origin of the supernumerary X chromosome is associated with later onset of puberty and longer CAG repeats of the AR with later pubertal reactivation of the pituitary-testicular axis in KS boys. Identifying genetic factors that affect the phenotype may lead to a better understanding of the pathogenesis of KS.