Jörg Gromoll

Mutation in the follicle-stimulating hormone receptor gene causes hereditary hypergonadotropic ovarian failure

Hypergonadotropic ovarian dysgenesis (ODG) with normal karyotype is a heterogeneous condition that in some cases displays Mendelian recessive inheritance. By systematically searching for linkage in multiplex affected families, we mapped a locus for ODG to chromosome 2p. As the previously cloned follicle-stimulating hormone receptor (FSHR) gene had been assigned to 2p, we searched it for mutations. A C566T transition in exon 7 of FSHR predicting an Ala to Val substitution at residue 189 in the extracellular ligand-binding domain segregated perfectly with the disease phenotype. Expression of the gene in transfected cells demonstrated a dramatic reduction of binding capacity and signal transduction, but apparently normal ligand-binding affinity of the mutated receptor. We conclude that the mutation causes ODG in these families.

Derivation of male germ cells from bone marrow stem cells

Recent studies have demonstrated that somatic stem cells have a more flexible potential than expected, whether put into tissue or cultured under different conditions. Bone marrow (BM)-derived stem cells can transdifferentiate into multilineage cells, such as muscle of mesoderm, lung and liver of endoderm, and brain and skin of ectoderm origin. Here we show that BM stem cells are able to transdifferentiate into male germ cells. For derivation of male germ cells from adult BM stem (BMS) cells, we used the Stra8-enhanced green fluoresence protein (EGFP) transgenic mouse line expressing EGFP specifically in male germ cells. BMS cell-derived germ cells expressed the known molecular markers of primordial germ cells, such as fragilis, stella, Rnf17, Mvh and Oct4; as well as molecular markers of spermatogonial stem cells and spermatogonia including Rbm, c-Kit, Tex18, Stra8, Piwil2, Dazl, Hsp90α, β1- and α6-integrins. Our ability to derive male germ cells from BMS cells reveals novel aspects of germ cell development and opens the possibilities for use of these cells in reproductive medicine.

Screening for Deletions of the Y Chromosome Involving the DAZ (Deleted in Azoospermia) Gene in Azoospermia and Severe Oligozoospermia

OBJECTIVE To evaluate the occurrence and prevalence of microdeletions of the Y chromosome involving the DAZ (Deleted in AZoospermia) gene in patients with azoospermia or severe oligozoospermia. DESIGN Controlled clinical study. SETTING University infertility clinic. PATIENT(S) Infertile men (n = 168) with nonobstructive, idiopathic azoospermia or severe oligozoospermia and normal LH. The control group consisted of proven fathers (n = 86). INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Semen analysis; polymerase chain reaction amplification of the loci sY84, sY143, sY254, and sY255; serum FSH, LH, and T; testicular volume. RESULT(S) Deletions involving the sY254 and sY255 DAZ loci were found in three azoospermic patients and two men with sperm concentration < 1 x 10(6)/mL. Serum FSH was elevated in four patients and was normal in one. All five patients had decreased testicular volumes compared with controls. No deletions involving the sY84 and sY143 loci were found. The four loci were amplified normally in the control group. CONCLUSION(S) The estimated frequency of deletions involving the DAZ locus is 3% in azoospermic-severely oligozoospermic men consulting an infertility clinic. Polymerase chain reaction amplification of the DAZ locus is useful for the diagnosis of microdeletions of the Y chromosome. Deletions involving more proximal regions of the Y chromosome seem to be rare.

Idiopathic male infertility is strongly associated with aberrant methylation of MEST and IGF2/H19 ICR1

Aberrant imprinting in spermatozoa in a subset of infertile men has been postulated to be a risk factor for congenital diseases in children conceived via assisted reproduction techniques (ART). Studies in clinically well characterized large cohorts, however, have been missing. Using bisulfite sequencing, we determined the degree of methylation of the IGF2/H19 imprinting control region 1 (ICR1) and MEST differentially methylated regions in swim-up purified spermatozoa from 148 idiopathic infertile men and 33 normozoospermic controls. All control individuals had a high degree of IGF2/H19 ICR1 and a low degree of MEST methylation. Low sperm counts were clearly associated with IGF2/H19 ICR1 hypomethylation and, even stronger, with MEST hypermethylation. MEST hypermethylation, but not IGF2/H19 ICR1 hypomethylation was found in idiopathic infertile men with progressive sperm motility below 40% and bad sperm morphology below 5% normal spermatozoa. Ageing could be ruled out as a cause for the observed methylation defects. Sequence analysis of the CTCFL gene in peripheral blood DNA from 20 men with severe methylation defects revealed several polymorphisms, but no bona fide mutation. We conclude that idiopathic male infertility is strongly associated with imprinting defects at IGF2/H19 ICR1 and MEST, with aberrant MEST methylation being a strong indicator for sperm quality. The male germ cell thus represents a potential source for aberrant epigenetic features in children conceived via ART.

The CAG repeat polymorphism in the androgen receptor gene affects bone density and bone metabolism in healthy males

OBJECTIVE Bone metabolism and bone density (BD) are influenced by sex hormones. Testosterone (T) action is exerted through the androgen receptor (AR). We investigated the potential impact of the CAG repeat (CAGR) polymorphism within the AR gene on BD and bone metabolism in healthy younger males.

Clinical consequences of microdeletions of the Y chromosome: the extended Münster experience

A total of 3179 patients were screened for Y-chromosome microdeletions and 821 patients for partial AZFc deletions. Thirty-nine Y-chromosomal microdeletions were found (2.4% of men with <1 x 10(6)/ml spermatozoa): two AZFa, two AZFb, one AZFbc, one partial AZFb, one partial AZFb+c and 32 AZFc (b2/b4). Partial AZFc deletions were found in 45 patients (5.5%), mostly gr/gr deletions (n = 28). In patients with AZFc deletion, azoospermia was found in 53.1% and sperm concentrations of mostly <0.1 x 10(6)/ml were found in 46.9%. Semen analyses and FSH measurements showed no trend over time. Elongated spermatids were seen in 6/15 AZFc patients and bilateral Sertoli cell-only was found in 4/15. Testicular sperm extraction (TESE) was attempted in 10 patients and spermatozoa were found in six. Compared with infertile men matched by sperm concentration, no differences in hormonal and seminal parameters could be found in patients with AZFc or gr/gr deletions. It is concluded that: (i) frequency of AZF deletions in Germany is much lower than in other countries; (ii) AZFc deletions are associated with severe disturbances of spermatogenesis and TESE is not possible in half of these patients; (iii) AZFc and gr/ gr deletions are not associated with any clinical diagnostic parameter; (iv) and no trend is apparent over time.

Genetic complexity of FSH receptor function

The interaction between follicle-stimulating hormone (FSH) and the FSH receptor (FSHR) is essential for normal oogenesis and spermatogenesis. Recently, single-nucleotide polymorphisms (SNPs) have been assigned to the FSHR gene. These give rise to different FSHR haplotypes that modify the action of FSH. In women, FSH sensitivities during the menstrual cycle and different cycle lengths are observed, depending on the FSHR haplotype. Thus, SNPs of the FSHR determine the ovarian response and should, therefore, be considered in controlled ovarian hyperstimulation during assisted-reproduction techniques in women with normal ovarian function. In men, the impact of the FSHR SNPs is unclear. The genetic complexity of FSHR should be considered when studying FSH action. These SNPs are one of the first examples in which genetic changes contribute to fine-tuning the endocrine regulation of reproduction. A rational pharmacogenetic approach that combines FSH dose according to the FSHR haplotype is envisaged.

Testosterone Replacement Effectively Inhibits the Development of Experimental Autoimmune Orchitis in Rats: Evidence for a Direct Role of Testosterone on Regulatory T Cell Expansion

Despite the immune-privileged status of the male genital tract, infection and inflammation of the male genital tract are important etiological factors in male infertility. A common observation in clinical and experimental orchitis as well as in systemic infection and inflammation are decreased levels of testosterone. Emerging data point to an immunosuppressive role of testosterone. In our study, we substituted testosterone levels in experimental autoimmune orchitis (EAO) in rat by s.c. testosterone implants. EAO development was reduced to 17% when animals were treated with low-dose testosterone implants (3 cm long, EAO+T3) and to 33% when rats were supplied with high-dose testosterone implants (24 cm, EAO+T24) compared with 80% of animals developing disease in the EAO control group. In the testis, testosterone replacement in EAO animals prevented the accumulation of macrophages and significantly reduced the number of CD4+ T cells with a strong concomitant increase in the number of regulatory T cells (CD4+CD25+Foxp3+) compared with EAO control. In vitro testosterone treatment of naive T cells led to an expansion of the regulatory T cell subset with suppressive activity and ameliorated MCP-1–stimulated chemotaxis of T lymphocytes in a Transwell assay. Moreover, expression of proinflammatory mediators such as MCP-1, TNF-α, and IL-6 in the testis and secretion of Th1 cytokines such as IFN-γ and IL-2 by mononuclear cells isolated from testicular draining lymph nodes were decreased in the EAO+T3 and EAO+T24 groups. Thus, our study shows an immunomodulatory and protective effect of testosterone substitution in the pathogenesis of EAO and suggests androgens as a new factor in the differentiation of regulatory T cells.

Functional and clinical consequences of mutations in the FSH receptor

The follicle-stimulating hormone (FSH) is essential for normal gametogenesis. In females FSH is required for ovarian development and follicle maturation whereas in males FSH determines Sertoli cell number and quantitatively and qualitatively normal spermatogenesis. FSH action is mediated by a G-protein coupled receptor expressed solely in granulosa and Sertoli cells. The FSH-receptor (FSHR) gene is localized on chromosome 2 p21 and spans a region of 54 kb. It consists of ten exons; exon one to nine encode the large extracellular domain and the transmembrane domain is comprised of exon ten. Mutations in the FSHR gene could severely affect gametogenesis and result in infertility. Therefore screening programs have been initiated, in which patients with disturbed fertility were searched for mutations in the FSHR gene. Several Finnish families were identified displaying an inherited pattern of ovarian dysgenesis, a disease leading to streaky underdeveloped ovaries and primary amenorrhea. By genetic linkage the locus of the genetic defect was confined to chromosome 2 p21. Analysis of the FSHR gene resulted in the identification of a mutation (Ala189Val) homozygous in all affected females. Functional studies revealed that the mutation affects the proper protein folding and thereby inactivates the receptor. In a male patient hypophysectomized because of a pituitary tumor, who despite undetectable serum gonadotropins had normal semen parameters, we hypothesized an activating mutation of the FSHR. Screening of exon ten of the FSHR gene resulted in the identification of a Asp567Gly transition in the third intracytoplasmatic loop. Functional studies resulted in a 1.5-fold increase in basal cAMP production compared to wild type FSHR, indicating that the heterozygous mutation leads to a ligand-independent constitutive activation of the FSHR. This patient provides an exceptional model of nature defining the role of FSH in human spermatogenesis. Mutations of the FSHR might have differential effects in each gender. For example activating mutations have not been described in women, therefore it is not clear whether the constitutive activity of the receptor could disturb normal follicular development resulting in certain infertility.

Follicle-stimulating hormone receptor polymorphisms in women with normogonadotropic anovulatory infertility

OBJECTIVE To assess the incidence of different FSH receptor genotypes in normogonadotropic anovulatory infertile women (World Health Organization class II) and normo-ovulatory controls and to correlate these genotypes with baseline characteristics and ovarian responsiveness during ovulation induction. DESIGN Cross-sectional study. SETTING University hospital. PATIENT(S) Thirty normo-ovulatory controls and 148 normogonadotropic anovulatory infertile women. INTERVENTION(S) All participants underwent a standardized evaluation that included cycle history, body mass index measurement, and transvaginal ultrasonography of ovaries. Fasting blood samples were obtained for endocrine evaluation. Ovarian responsiveness to FSH in normogonadotropic anovulatory infertile women was assessed during ovulation induction, and DNA was analyzed to determine the FSH receptor genotype. MAIN OUTCOME MEASURE(S) Prevalence of FSH receptor polymorphisms, baseline serum FSH levels, amount of FSH administered, duration of stimulation, and ovarian response dose. RESULT(S) The Thr/Thr 307 genotype was significantly less prevalent (52% vs. 23%) and the Ser/Ser 680 polymorphism was significantly more prevalent (40% vs. 16%) in patients compared with controls. Normogonadotropic anovulatory infertile women with the Ser/Ser 680 polymorphism presented with higher median FSH serum levels (5.2 IU/L [range, 2.4-9.7 IU/L]) than did those with the Asn/Asn 680 (4.6 IU/L [range, 1.4-5.8 IU/L) and Asn/Ser 680 (4.5 IU/L [range, 1.8-9.7 IU/L) variants. However, ovarian responsiveness to FSH was similar among anovulatory women with the various polymorphisms. CONCLUSION(S) Normogonadotropic anovulatory infertile patients have a different FSH receptor genotype than do normo-ovulatory controls. Although this characteristic is associated with increased baseline FSH serum levels, altered ovarian sensitivity to exogenous FSH during ovulation induction could not be established.