Isolated FSH deficiency in a male. A case report

Impaired fertility and FSH synthesis in gonadotrope-specific Foxl2 knockout mice

Impairments in pituitary FSH synthesis or action cause infertility. However, causes of FSH dysregulation are poorly described, in part because of our incomplete understanding of mechanisms controlling FSH synthesis. Previously, we discovered a critical role for forkhead protein L2 (FOXL2) in activin-stimulated FSH β-subunit (Fshb) transcription in immortalized cells in vitro. Here, we tested the hypothesis that FOXL2 is required for FSH synthesis in vivo. Using a Cre/lox approach, we selectively ablated Foxl2 in murine anterior pituitary gonadotrope cells. Conditional knockout (cKO) mice developed overtly normally but were subfertile in adulthood. Testis size and spermatogenesis were significantly impaired in cKO males. cKO females exhibited reduced ovarian weight and ovulated fewer oocytes in natural estrous cycles compared with controls. In contrast, ovaries of juvenile cKO females showed normal responses to exogenous gonadotropin stimulation. Both male and female cKO mice were FSH deficient, secondary to diminished pituitary Fshb mRNA production. Basal and activin-stimulated Fshb expression was similarly impaired in Foxl2 depleted primary pituitary cultures. Collectively, these data definitively establish FOXL2 as the first identified gonadotrope-restricted transcription factor required for selective FSH synthesis in vivo.

Apparent primary follicle-stimulating hormone deficiency is a rare cause of treatable male infertility

OBJECTIVE

To find the underlying defect in a case of primary FSH deficiency and to estimate the beneficial effect of FSH treatment.

DESIGN

Case report.

SETTING

University hospital fertility clinic.

PATIENT(S)

Normal, healthy, 37-year-old male patient with severe oligoteratozoospermia.

INTERVENTION(S)

Levels of FSH, LH, LHRH provocation test, karyotyping, genomic analysis on the Y-chromosomal AZF region and sequencing of the FSHB gene, FSH treatment.

MAIN OUTCOME MEASURE(S)

We compiled detailed clinical and molecular data on four pregnancies. We compare this case with a similar case published recently.

RESULT(S)

There were detectable but very low FSH levels after LHRH provocation; the LH response was not entirely normal, and no genomic abnormalities were found in the FSHB gene. The FSH treatment resulted in four pregnancies, two of which ended in abortion; the other two resulted in the birth of two healthy children. Both our case and the published case had detectable but abnormally low FSH levels on some occasions, but normal or highly normal inhibin B levels that differed from the expected low levels. Both patients had a normal male phenotype and no detectable mutation in the FSHB gene. The published case differed from our patient in that the published case was azoospermic whereas ours was extremely oligoteratozoospermic. The beneficial effect of FSH treatment was only shown in our patient.

CONCLUSION(S)

The published case and ours may have a common, as yet unidentified, underlying defect. The dramatic and immediate effect of FSH treatment on our patient's fertility was clearly demonstrated.

Men with acquired hypogonadotropic hypogonadism treated with testosterone may be fertile

Men with acquired hypogonadotropic hypogonadism treated with testosterone are generally assumed to be infertile. The finding of two such patients with unexpected fertility and normal sperm counts prompted an evaluation of spermatogenesis in additional men with this condition. Case records were initially searched and one similar case with fertility was found. Subsequently, 12 consecutive men with acquired hypogonadotropic hypogonadism were evaluated for gonadal function and sperm production while receiving testosterone. In five of the cases with proven spermatogenesis, exon 10 of the FSH receptor was sequenced to look for activating mutations. The original three cases and four of the subsequent 12 men had sperm concentrations > or = 15 million/ml. Two additional men had concentrations of 1 million/ml and six were azoospermic. Residual LH and FSH levels were slightly higher in those with maintained spermatogenesis prior to testosterone replacement. No activating mutations were found in exon 10 of the FSH receptor in the five cases studied. We conclude that men with acquired hypogonadotropic hypogonadism being treated with testosterone should not be assumed to be sterile, as we have found that more than half have been shown to have persistent spermatogenesis with more than one-third having sperm concentrations > or = 15 million/ml. This may be related to fact that gonadotropin levels in such patients are present, albeit low. Semen analyses in such men should be routinely carried out so that they can be appropriately counseled regarding potential fertility.

The functional significance of FSH in spermatogenesis and the control of its secretion in male primates

The aim of this review is to provide an integrative analysis of the role of FSH in the control of testicular function in higher primates, including man. Attention is focused on the action of FSH during neonatal development, puberty, and adulthood. Whether FSH is the major determinant of the adult complement of Sertoli cells and whether FSH is obligatory for the initiation, maintenance, and restoration of spermatogenesis is evaluated. The mechanism whereby the circulating concentration of FSH regulates spermatogonial proliferation to dictate the sperm production rate under physiological conditions in the adult is discussed in detail. Inhibin B is the major component of the testicular negative feedback signal governing FSH beta gene expression and FSH secretion, and the evidence for this view is presented. The review concludes with the presentation of a model for the operation of the FSH-inhibin B feedback control system regulating sperm production postpubertally in monkey and man, and with speculation on issues of clinical interest.

Mutations of gonadotropins and gonadotropin receptors: elucidating the physiology and pathophysiology of pituitary-gonadal function

The recent unraveling of structures of genes for the gonadotropin subunits and gonadotropin receptors has provided reproductive endocrinologists with new tools to study normal and pathological functions of the hypothalamic-pituitary-gonadal axis. Rare inactivating mutations that produce distinctive phenotypes of isolated LH or FSH deficiency have been discovered in gonadotropin subunit genes. In addition, there is a common polymorphism in the LHbeta subunit gene with possible clinical significance as a contributing factor to pathologies of LH-dependent gonadal functions. Both activating and inactivating mutations have been detected in the gonadotropin receptor genes, a larger number in the LH receptor gene, but so far only a few in the gene for the FSH receptor. These mutations corroborate and extend our knowledge of clinical consequences of gonadotropin resistance and inappropriate gonadotropin action. The information obtained from human mutations has been complemented by animal models with disrupted or inappropriately activated gonadotropin ligand or receptor genes. These clinical and experimental genetic disease models form a powerful tool for exploring the physiology and pathophysiology of gonadotropin function and provide an excellent example of the power of molecular biological approaches in the study of pathogenesis of diseases.

Clinical studies in an adult male patient with "isolated follicle stimulating hormone (FSH) deficiency"

Previous reports concerning isolated follicle stimulating hormone (FSH) deficiency and its possible pathogenesis have been conflicting. Both "normal" and "abnormal" FSH response to luteinizing hormone releasing hormone (LHRH) infusion have been described. We studied a 22-year-old man with normal basal serum testosterone and luteinizing hormone (LH) levels but undetectable levels of serum FSH. His serum LH titers showed one secretory spike during a 40-hour sampling at 20-minute intervals, whereas his serum FSH titers remained undetectable (less than 0.4 IU/l). Infusion of LHRH, 0.2 microgram/minute for 4 hours, induced the expected rise in the serum LH levels, but serum FSH levels remained low and only at one point reached 0.9 IU/l (normal adult male basal range 0.9-10.3 IU/l). The patient received LHRH, 100 micrograms/day, for three days. A second LHRH infusion, 0.2 microgram/minute for 4 hours, induced a normal rise in both the serum LH and FSH titers. The serum sex steroid binding globulin level was 10.3 ng DHT bound/ml (normal adult male level 8.0 +/- 0.3 ng DHT bound/ml). Presence of circulating auto-antibodies to the serum FSH was excluded by determining the binding of [125I] FSH with the patient's serum and comparing it with sera obtained from two normal male adult volunteers. Pituitary function tests were otherwise intact. Presence of a pituitary tumor was excluded by computerized axial tomography and x-ray studies of the pituitary fossa and normal visual fields. Clinically, the patient demonstrated cryptorchidism, hypospadias, surgically repaired omphalocele, and bilateral hearing loss.(ABSTRACT TRUNCATED AT 250 WORDS)