Selective deficiency of Gsalpha and the possible role of alternative gene products of GNAS in Albright hereditary osteodystrophy and pseudohypoparathyroidism type Ia.

OBJECTIVE: Albright hereditary osteodystrophy (AHO) and Pseudohypoparathyroidism type Ia (PHPIa) are caused by an inherited deficiency of Gsalpha, encoded by the GNAS gene. Apart from an exclusive first exon, Gsalpha shares part of the transcribed regions with NESP55, Exon A/B and XLalphas, whose gene products utilize alternative promoter regions of this complex gene locus. However, it is not known, whether the deficiency of all gene products contributes to the AHO and PHPIa phenotype or if they are even causative for some specific symptoms. In these cases, mutations affecting selectively GNAS exon 1, coding only for Gsalpha, would lead to a different phenotype than mutations affecting the common exons 2-13. METHODS: Clinical and molecular genetic analysis of a patient with features of AHO and review of exclusive exon 1 mutations of GNAS. RESULTS: We detected a novel heterozygous 1 bp deletion of a guanine in codon 31 in exon 1 of the GNAS gene leading to a frame shift and premature termination of Gsalpha. The female patient demonstrated a fully expressed AHO and PHPIa phenotype and a decreased Gsalpha protein activity of 62% compared to the wild type. Mutations in exon 1 are almost exclusively disruptive and lead to an AHO phenotype that does not show obvious differences from those provoked by missense or nonsense mutations in exon 2-13. CONCLUSION: Disruptive mutations in exon 1 indicate that exclusive deficiency of Gsalpha is sufficient for the expression of an AHO phenotype, which cannot be compensated by alternative products of GNAS.

Developing effective screening strategies in multiple endocrine neoplasia type 1 (MEN 1) on the basis of clinical and sequencing data of German patients with MEN 1.

BACKGROUND: Multiple-endocrine-neoplasia-type-1 (MEN1) is an autosomal-dominant inherited disorder characterized by the combined occurrence of primary hyperparathyroidism (pHPT), gastroenteropancreatic neuroendocrine tumors (GEP), adenomas of the pituitary gland (APA), adrenal cortical tumors (ADR) and other tumors. As the tumors appear in an unpredictable schedule, uncertainty about screening programs is persisting. OBJECTIVE: To optimize screening and to analyze possible differences in sporadic versus familial cases. METHODS: We analyzed data of 419 individuals including 306 MEN-1 patients (138 isolated and168 familial cases out of 102 unrelated families). RESULTS: A total of 683 tumors occurred consisting of 273 pHPT, 138 APA, 166 GEP, 57 ADR, 24 thymic- and bronchial-carcinoids as well as 25 neoplasms of other tissues. The age-related penetrance was determined as 10%, 35%, 67%, 81% and 100% at 20, 30, 40, 50 and 65 years respectively. Although pHPT being the most frequent first manifestation (41%), also GEP (22%) or APA (21%) were found to be the first presentation. APA occurred significantly more frequent (p<0,05) in isolated (n=138) than in familial (n=168) cases, whereas GEP showed a tendency to occur more often in familial cases. Genotype/phenotype correlation in 140 clinically affected MEN-1 cases showed a tendency for truncating mutations, especially nonsense mutations to be associated to GEP and carcinoids of the lungs and thymus. CONCLUSION: In view of the morbidity and frequency in familial cases an effective screening programme should aim at an early diagnosis of GEP particularly when truncating, especially nonsense mutations are found.

Long-term outcome in 46 gene carriers of hereditary medullary thyroid carcinoma after prophylactic thyroidectomy: impact of individual RET genotype.

OBJECTIVE: In children with RET proto-oncogene mutation, curative treatment of medullary thyroid carcinoma (MTC) is possible by prophylactic thyroidectomy. Recommendations on the timing and extent of thyroidectomy are based upon a model that utilises genotype-phenotype correlations to stratify mutations into three risk groups. DESIGN: We evaluated the long-term outcome (mean follow-up 6.4 years, 15 patients more than 10 years, 26 patients more than 5 years) of operated gene carriers stratified into two risk groups (levels 1 and 2) based on the biological aggressiveness of MTC. RESULTS: In 46 RET gene carriers, prophylactic thyroidectomy was carried out between the ages of 4 and 21 years. Level 1 mutations were harboured by 11 patients (codons 790, 791, 804 and 891). Histology was completely normal in two patients; in seven patients C-cell hyperplasia (CCH) and in two patients T1 tumours were diagnosed. All patients with level 1 mutations were cured. Level 2 mutations were harboured by 35 patients (codons 618, 620, 630 and 634). Histology of these patients showed CCH in 11 patients, T1 tumours in 21, T2 tumour in 1, T3 tumour in 1 and Tx in 1 patient. Histology showed no lymph node involvement. Five patients with level 2 mutations failed to be cured; in two patients, persistence of MTC was diagnosed directly after thyroidectomy and in three during follow-up. In two patients carrying a 634 mutation, other endocrinopathies (hyperparathyroidism and bilateral pheochromocytoma) manifested during follow-up. CONCLUSIONS: If prophylactic thyroidectomy is done at early ages, cure rate is high. Timing and extent of prophylactic thyroidectomy can be modified by individual RET mutation.

[Hereditary medullary thyroid carcinoma--genotype-phenotype characterization]. / Hereditäres medulläres Schilddrüsenkarzinom--Genotyp-Phänotyp Charakterisierung.

BACKGROUND AND OBJECTIVE: Hereditary medullary thyroid carcinoma (MTC) is caused by germline mutations of the RET proto-oncogene. A genotype - phenotype correlation has been established, showing clustering of mutations in exons 10 and 11 in classical MEN 2 A syndrome, in exon 16 codon 918 in MEN 2 B syndrome and in exons 13-15 in familial MTC. A line of evidence suggested that the development and the aggressiveness of MTC in the different cancer syndromes is variable. Aim of this study was to compare the phenotype of exon 13-15 mutations with that of exon 11 mutation and possibly draw therapeutical consequences. PATIENTS AND METHODS: We compared the phenotype of 47 patients with mutations in exon 13-15 with 66 patients with exon 11, codon 634 mutation, the classical MEN2A. Patients were further subdivided as index and screening patients. RESULTS: Mean age of 19 index patients with codon 790, 791, 804 or 891 mutation was significant higher compared with 18 index patients with codon 634 mutation (mean age at diagnosis 50+/-12 years; range 30-69 y vs mean age 31+/-9 years; range 17-49 y), tumor stage at operation was favourable (C-cell hyperplasia n = 1; stage I n = 8; II n = 3; III n = 2; IV n = 2; no operation n = 1; no information n = 2 vs stage I n = 3; stage II n = 6; stage III n = 4, no information n =5), cure rate was better (56 % vs 38 %) and the death rate was lower (n = 2 vs n = 4). In screening patients no differences concerning the age, tumor stage, cure and death rate between patients with exons 13-15 and codon 634 mutations were seen. CONCLUSIONS: MTC in patients with exon 790, 791, 804, 891 mutations displayed a late onset and an indolent course compared to codon 634 mutation, this has to be taken into account when recommending timing and extent of prophylactic surgery.

Inhibition of Ret oncogene activity by the protein tyrosine phosphatase SHP1.

Germline mutations in the Ret protooncogene give rise to the inherited endocrine cancer syndromes MEN types 2A and 2B and familiar medullary thyroid carcinoma. Although it is well accepted that the constitutive active tyrosine kinase of Ret oncogenes ultimately leads to malignant transformation, it is not clear whether a decrease in the autophosphorylation of oncogenic Ret forms can affect the mitogenic and transforming activities of Ret. Potential modulators of the tyrosine kinase activity of Ret could be tyrosine phosphatases that are expressed in human thyroid tissue. Therefore, we investigated the impact of the tyrosine phosphatases SHP1 and SHP2 on the intrinsic tyrosine kinase activity and oncogenic potency of Ret with a 9-bp duplication in the cysteine-rich domain (codons 634-636), which was described in a patient with MEN type 2A recently. SHP1 and SHP2 were stably overexpressed in NIH3T3 fibroblasts together with Ret-9bp. Coexpression of SHP1 with Ret-9bp reduced the autophosphorylation of Ret-9bp by 19 +/- 7% (P = 0.01, n = 4), whereas no effect was seen with SHP2. Furthermore, Ret-9bp could be coimmunoprecipitated with SHP1 but not with SHP2 antibodies. Suppression of the Ret-9bp tyrosine kinase activity by SHP1 caused a decrease in activation of Erk2 (extracellular signal-regulated kinase) and abolished PKB/Akt (protein kinase B) phosphorylation. In addition, diminished Ret-9bp autophosphorylation led to reduced phosphorylation of the transcription factor jun-D. Finally, the inhibitory effect on Ret-9bp signaling resulted in a 40-60% reduction of [(3)H]thymidine incorporation and in reduced ability of NIH3T3 cells to form colonies in soft agar. In conclusion, the data suggest that SHP1 caused a moderate reduction of Ret autophosphorylation, which led to a strong suppression of the Ret oncogene activity.

Typical ocular findings in a patient with multiple endocrine neoplasia type 2b syndrome.

BACKGROUND: Multiple endocrine neoplasia (MEN) type 2b syndrome is accompanied by typical ocular findings; however, the disease is often only diagnosed at an advanced stage by symptoms of C-cell carcinoma or pheochromocytoma and is then fatal in most cases. Therefore, the importance of ophthalmic assessment in making the diagnosis has to be stressed. METHODS: The history and ocular findings of a patient with MEN 2b syndrome are described, and a brief overview of the syndrome is given. RESULTS: Slit-lamp examination showed extremely thickened corneal nerves as well as multiple small plexiform and nodular subconjunctival tumors. Both eyes also displayed thickened upper and lower eyelids. A molecular genetic study of the RET proto-oncogene showed a heterozygous ATG to ACG mutation in codon 918 of exon 16. CONCLUSION: Greatly thickened corneal nerves and subconjunctival tumors may be the first hint of MEN 2b. Whenever greatly thickened corneal nerves are detected, MEN 2b must be ruled out.

Presentation of a kindred with familial medullary thyroid carcinoma and Cys611Phe mutation of the RET proto-oncogene demonstrating low grade malignancy.

OBJECTIVE: Both multiple endocrine neoplasia type 2A (MEN 2A) and familial medullary thyroid carcinoma (FMTC) are caused by germline mutations of the RET proto-oncogene. A broad spectrum of malignancy within and between families has been described with no clear genotype-phenotype correlation due to a scarcity of available data of large kindreds. DESIGN: Here we present the only known family with a germline mutation of codon 611 TGC to TTC (exon 10) in the RET proto-oncogene leading to a replacement of cysteine by phenylalanine (Cys611Phe or C611F). RESULTS: Twenty family members of this large kindred are gene carriers (GCs) and seven (5-13 years old) are potential carriers but have yet to be analysed. The clinical course of medullary thyroid carcinoma (MTC) in this family is characterized by a very slow evolution and progression of the tumour with no MTC-related death to date. Of 11 patients (30-69 years old) having undergone thyroidectomy six were classified as pT1, four as pT2 and one as C-cell hyperplasia according to the TNM system of the International Union Against Cancer. Due to cervical and mediastinal lymph node metastasis one patient (44 years old) had to be operated on a second time. The seven non-operated GCs of the fourth and fifth generation (17-26 years old) are yearly monitored with pentagastrin stimulation tests; one non-operated GC (43 years old) has refused any further investigations. Screening for primary hyperparathyroidism and phaeochromocytoma was negative in all cases. CONCLUSION: We suggest from these experiences that the general advice for thyroidectomy in early childhood should be modified in certain families, depending on genotype.

Molecular genetic alterations on chromosomes 11 and 22 in ependymomas.

Ependymomas arise from the ependymal cells at different locations throughout the brain and spinal cord. These tumors have a broad age distribution with a range from less than 1 year to more than 80 years. In some intramedullary spinal ependymomas, mutations in the neurofibromatosis 2 (NF2) gene and loss of heterozygosity (LOH) on chromosome arm 22q have been described. Cytogenetic studies have also identified alterations involving chromosome arm 11q, including rearrangements at 11q13, in ependymomas. We analyzed 21 intramedullary spinal, 14 ventricular, 11 filum terminale and 6 intracerebral ependymomas for mutations in the MEN1 gene, which is located at 11q13, and mutations in the NF2 gene, which is located at 22q12, as well as for LOH on 11q and 22q. NF2 mutations were found in 6 tumors, all of which were intramedullary spinal and all of which displayed LOH 22q. Allelic loss on 22q was found in 20 cases and was significantly more frequent in intramedullary spinal ependymomas than in tumors in other locations. LOH 11q was found in 7 patients and exhibited a highly significant inverse association with LOH 22q (p<0.001). A hemizygous MEN1 mutation was identified in 3 tumors, all of which were recurrences from the same patient. Interestingly, the initial tumor corresponded to WHO grade II and displayed LOH 11q but not yet a MEN1 mutation. In 2 subsequent recurrences, the tumor had progressed to anaplastic ependymoma (WHO grade III) and exhibited a nonsense mutation in exon 10 of MEN1 (W471X) in conjunction with LOH 11q. This suggests that loss of wild-type MEN1 may be involved in the malignant progression of a subset of ependymomas. To conclude, our findings provide evidence for different genetic pathways involved in ependymoma formation and progression, which may allow to define genetically and clinically distinct tumor entities.

Genotype-phenotype correlations in hereditary medullary thyroid carcinoma: oncological features and biochemical properties.

In hereditary medullary thyroid carcinoma (MTC), few genotype-phenotype correlations have been established. RET genotypes (exons 10, 11, 13, and 14) of 63 patients with hereditary MTC (from November 1994 to October 1999) were correlated with age at diagnosis, sex, the TNM system, and basal calcitonin levels. Mutations in exons 10, 11, 13, and 14 were demonstrated in 22% (14 of 63), 54% (34 of 63), 21% (13 of 63), and 3% (2 of 63). The median ages at diagnosis differed significantly (38, 27, 52, and 62 yr; P = 0.003). When grouped by cysteine codons (exons 10 and 11 vs. exons 13 and 14), this difference became even more evident (30 vs. 56 yr; P = 0.001). Apart from age at diagnosis, no other significant associations were noted. Based hereon, three MTC risk groups were devised according to genotype: a high risk group (codons 634 and 618) with the youngest ages of 3 and 7 yr at diagnosis; an intermediate risk group (codons 790, 620, and 611) with ages of 12, 34, and 42 yr; and a low risk group (codons 768 and 804) with ages of 47 and 60 yr, respectively. Age at diagnosis was unrelated to specific nucleotide and amino acid exchange within each codon. The current data demonstrate that there is a significant genotype-phenotype correlation, allowing for a more individualized approach to the timing and extent of prophylactic surgery.

Prognostic value of codon 918 (ATG-->ACG) RET proto-oncogene mutations in sporadic medullary thyroid carcinoma.

We have determined the frequency of 918 RET proto-oncogene mutations (ATG-->ACG) in primary MTC tumors and metastases and correlated the presence or absence of this mutation with the clinical outcome of patients suffering from sporadic medullary thyroid carcinoma (MTC). A total of 197 samples, consisting of both primary tumors and lymph node metastases from 34 patients with sporadic MTC, were collected for PCR analysis of the RET 918 mutation. In 75 of the samples (38%), codon 918 (ATG-->ACG) mutations could be detected. The mutations showed a heterogeneous distribution: 21/34 patients (62%) had mutations in at least 1 tumor sample, and in 13 patients (38%) the mutation was present in all examined samples. Patients were considered 918mt when at least 1 tumor sample showed the RET 918 mutation. These 918mt and 918 wild-type (918wt) patients did not differ significantly concerning sex, age at diagnosis, TNM stage at diagnosis, number of examined tumor samples or follow-up time. However, 918mt patients showed more aggressive development of distant metastases during follow-up (p = 0.032, Fisher's exact test) with decreased metastases-free survival (p < 0.005, log-rank test). Furthermore, 918mt patients had a significantly lower survival rate than 918wt patients (p = 0.048, log-rank test). These data show that the RET codon 918 mutation has a prognostic impact on patients with sporadic MTC which may influence follow-up treatment.

Quality assurance in RT-PCR-based BCR/ABL diagnostics--results of an interlaboratory test and a standardization approach.

Here we describe the results of an interlaboratory test for RT-PCR-based BCR/ABL analysis. The test was organized in two parts. The number of participating laboratories in the first and second part was 27 and 20, respectively. In the first part samples containing various concentrations of plasmids with the ela2, b2a2 or b3a2 BCR/ABL transcripts were analyzed by PCR. In the second part of the test, cell samples containing various concentrations of BCR/ABL-positive cells were analyzed by RT-PCR. Overall PCR sensitivity was sufficient in approximately 90% of the tests, but a significant number of false positive results were obtained. There were significant differences in sensitivity in the cell-based analysis between the various participants. The results are discussed, and proposals are made regarding the choice of primers, controls, conditions for RNA extraction and reverse transcription.

Ret oncogene signal transduction via a IRS-2/PI 3-kinase/PKB and a SHC/Grb-2 dependent pathway: possible implication for transforming activity in NIH3T3 cells.

Multiple endocrine neoplasia 2A (MEN 2A) is an inherited disease caused by mutations of the Ret proto-oncogene. Although many different Ret mutations have been described, little is known about the signaling pathways triggered by the Ret oncogene. In this study, we have determined the signaling properties of a Ret-9bp duplication encoding amino acids 634-636, which was recently identified in a patient with all clinical features of the MEN 2A syndrome. The Ret-9bp duplication leads to constitutive activation of the Ret tyrosine kinase. Furthermore, Ret-9bp increased mitogenic and transforming activity demonstrated by thymidine incorporation as well as colony formation in soft agar. Studying intracellular signaling pathways, which may be involved in malignant transformation of Ret-9bp expressing NIH3T3 cells, we could demonstrate Ret-9bp dependent phosphorylation of insulin receptor substrate-2 (IRS-2) with consecutive activation of phosphatidylinositol 3-kinase (PI 3-kinase) and protein kinase B (PKB/AKT). Moreover, Ret-9bp induces phosphorylation of SHC resulting in growth factor receptor binding protein-2 (Grb-2) binding and activation of the mitogen activating protein (MAP) kinase pathway. In addition to these postreceptor cytoplasmic signaling events, we have studied nuclear signal by Ret-9bp and found activation of c-jun and jun-D, two members of the jun/AP-1 family of transcription factors. In summary, an oncogenic 9bp duplication of Ret causes Ret dimer formation and ligand independent activation of the tyrosine kinase. Besides the signaling steps leading to MAPK activation, we could demonstrate that Ret-9bp induced constitutive activation of a signaling pathway involving IRS-2, PI 3-kinase and PKB/AKT which could transduce the oncogenic Ret signal to increased gene transcription via activation of the jun/AP-1 transcription factor family.

A novel type of mutation in the cysteine rich domain of the RET receptor causes ligand independent activation.

Multiple endocrine neoplasia type 2A (MEN 2A) is a dominantly inherited cancer syndrome, which involves the triad of MTC, pheochromocytoma, and hyperparathyroidism. Missense mutations in one of six cysteine codons in the extracellular cysteine-rich domain of the RET proto-oncogene predispose to this disease. These mutations cause ligand-independent constitutive activation of the tyrosine kinase receptor by the formation of disulfide-bonded homodimers. We examined a different type of mutation, which results in an additional cysteine in the cysteine rich domain. A duplication of 9 bp in the first case resulted in an insertion of three amino acids between codon 633 and 634. In the second case a 12 bp duplication in exon 11 results in four additional amino acids between codon 634 and 635. Here we demonstrate that an additional cysteine causes a ligand independent dimerization of the RET receptor in transfected NIH3T3 cells, which results in an activation of the intracellular tyrosine kinase.

A RET double mutation in the germline of a kindred with FMTC.

Activating germline mutations of the RET proto-oncogene are found in more than 90% of families with multiple endocrine neoplasia type 2a (MEN 2a) and familial medullary thyroid carcinoma (FMTC). The majority of patients with these hereditary tumors carry germline mutations that result in the substitution of one of five cysteine residues in exon 10 and 11. Different mutations in exons 13, 14 and 15 affecting non-cysteine residues have also been described but are considered to be rare. We now for the first time report a double mutation of the RET proto-oncogene occurring in the germline of a kindred with FMTC. Both mutations occur within the tyrosine kinase domain in exon 14 and lead to the substitution of valine 804 by methionine and arginine 844 by leucine. Since the double mutated allele cosegregated with the disease and was not identified in 200 unrelated normal probands, we conclude that they represent mutations that predispose the individual to the development of FMTC with a mild phenotype.

Lack of MEN1 gene mutations in 27 sporadic insulinomas.

BACKGROUND: Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal dominant familial cancer syndrome characterized by tumours of the parathyroids, anterior pituitary gland and endocrine pancreas. Since the cloning of the MEN1 gene (encoding menin) on chromosome 11q13 by Chandrasekharappa et al. in 1997, it has become possible to identify mutations that are responsible. We examined whether MEN1 gene mutations are present in sporadic insulinomas, a rare sporadic tumour that is seen more frequently in patients with the MEN 1 syndrome. PATIENTS AND METHODS: We sequenced the coding part of the MEN1 gene (exons 2-10) in tumour tissue of 27 patients suffering from an insulinoma (24 benign, three malignant). To validate our methods we also examined tumour tissue from five patients with primary hyperparathyroidism (HPT) at a younger age and/or multiple gland disease, with increased risk of MEN 1. RESULTS: We found no mutations in the nine coding exons of the MEN1 gene in the insulinoma tissues. We could confirm three benign polymorphisms (S145S, R171Q, D418D) reported previously. In the control patients we found two new point mutations (one mis-sense, one non-sense mutation) and one deletion. CONCLUSION: Mutations of the MEN1 gene do not play an important role in the pathogenesis of sporadic insulinomas. Therefore genetic screening is not cost effective in sporadic insulinoma patients without other indicators of MEN 1. Patients with primary HPT at a younger age and/or multiple gland disease should be screened for MEN1 gene mutations.

Detection of mutations in glycoprotein hormone receptors.

The luteinizing, follicle-stimulating, and thyroid-stimulating hormone receptors belong to the huge family of G-protein-coupled receptors. Identification of either activating or inactivating mutations of these receptors has led to a fundamental improvement in our understanding of glycoprotein hormone/receptor interaction. Furthermore, clinical phenotypes such as precocious puberty, follicle-stimulating hormone (FSH) insensitivity syndrome, and congenital hypthyroidism are now being explained by mutated glycoprotein hormone receptors. Since there is an ongoing worldwide search for certain clinical phenotypes that might be caused by mutations of these receptors, there is a demand for strategies and techniques that can be used to screen patients in a effective and reliable way. This article focuses, therefore, on patient selection and techniques for the detection of mutations of glycoprotein hormone receptors, and compiles useful laboratory protocols to conduct such studies.

Mutation screening and isoform prevalence of the follicle stimulating hormone receptor gene in women with premature ovarian failure, resistant ovary syndrome and polycystic ovary syndrome.

OBJECTIVE: To determine whether mutations in the FSH receptor gene are associated with premature ovarian failure (POF) or resistant ovary syndrome (ROS) in women in the UK. To determine whether an allelic variant of the FSH receptor gene affects fertility parameters in women with polycystic ovary syndrome (PCOS). DESIGN: A mutation screen using DNA from women with POF and ROS. Restriction digest of amplified DNA from women with POF, ROS, PCOS and controls to determine allelic variant status. Fertility parameters were compared between allelic variant subgroups of women with PCOS. PATIENTS: The study population comprised 49 women with POF, 5 with ROS, 93 with PCOS and 51 controls. MEASUREMENTS: In women with PCOS, fertility and menstrual status was recorded and serum FSH and ovarian volume were measured. RESULTS: No mutation of the FSH receptor gene was found in women with POF or ROS. The allelic variant Thr307/Ser680 was found to be similarly prevalent in all study groups. The Thr307/Ser680 variant was found to have no phenotype in terms of fertility parameters in women with PCOS. CONCLUSIONS: Mutations of the FSH receptor gene are rare in women with premature ovarian failure or resistant ovary syndrome in the UK. Polymorphisms of the FSH receptor gene do not appear to have pathophysiological significance with regard to ovarian function.

Secondary infertility as early symptom in a man with multiple endocrine neoplasia-type 1.

Multiple endocrine neoplasia-type 1 (MEN1) is an autosomal dominant familial cancer syndrome characterized by parathyroid hyperplasia, pancreatic endocrine tumours and pituitary adenomas. Here, we report a patient with a history of insulinoma who developed secondary infertility as a further symptom of the disease. When he was first examined at the age of 36 years, he complained of weakness, reduced libido and impotence. Laboratory evaluation revealed non-obstructive azoospermia and hyperprolactinaemia. In contrast to sexual activity and serum prolactin, semen quality did not significantly respond to bromocriptine therapy. During follow-up, a growing pituitary adenoma caused acromegaly with elevated serum concentrations of growth hormone, insulin-like growth factor 1 (IGF-1), and prolactin. After microsurgery of the tumour at the age of 44 years, sperm concentration persistently increased up to 5.6 x 10(6)/ml. In accordance with the clinical diagnosis of MEN1, DNA sequencing revealed a mutation in exon 2 of the menin gene which results in a truncated, inactive protein product. In conclusion, MEN1 with pituitary lesions may cause severe hypogonadism and infertility. Both hyperprolactinaemia and overproduction of growth hormone and IGF-1 seem to be involved in testicular dysfunction in the present case. The possible role of menin in the testis, however, remains to be elucidated.