Unraveling the intrafamilial correlations and heritability of tumor types in MEN1: a Groupe d'étude des Tumeurs Endocrines study

BACKGROUND

MEN1, which is secondary to the mutation of the MEN1 gene, is a rare autosomal-dominant disease that predisposes mutation carriers to endocrine tumors. Most studies demonstrated the absence of direct genotype-phenotype correlations. The existence of a higher risk of death in the Groupe d'étude des Tumeurs Endocrines-cohort associated with a mutation in the JunD interacting domain suggests heterogeneity across families in disease expressivity. This study aims to assess the existence of modifying genetic factors by estimating the intrafamilial correlations and heritability of the six main tumor types in MEN1.

METHODS

The study included 797 patients from 265 kindred and studied seven phenotypic criteria: parathyroid and pancreatic neuroendocrine tumors (NETs) and pituitary, adrenal, bronchial, and thymic (thNET) tumors and the presence of metastasis. Intrafamilial correlations and heritability estimates were calculated from family tree data using specific validated statistical analysis software.

RESULTS

Intrafamilial correlations were significant and decreased along parental degrees distance for pituitary, adrenal and thNETs. The heritability of these three tumor types was consistently strong and significant with 64% (s.e.m.=0.13; P<0.001) for pituitary tumor, 65% (s.e.m.=0.21; P<0.001) for adrenal tumors, and 97% (s.e.m.=0.41; P=0.006) for thNETs.

CONCLUSION

The present study shows the existence of modifying genetic factors for thymus, adrenal, and pituitary MEN1 tumor types. The identification of at-risk subgroups of individuals within cohorts is the first step toward personalization of care. Next generation sequencing on this subset of tumors will help identify the molecular basis of MEN1 variable genetic expressivity.

Whole-exome sequencing improves the diagnosis yield in sporadic infantile spasm syndrome

Infantile spasms syndrome (ISs) is characterized by clinical spasms with ictal electrodecrement, usually occurring before the age of 1 year and frequently associated with cognitive impairment. Etiology is widely heterogeneous, the cause remaining elusive in 40% of patients. We searched for de novo mutations in 10 probands with ISs and their parents using whole-exome sequencing (WES). Patients had neither consanguinity nor family history of epilepsy. Common causes of ISs were excluded by brain magnetic resonance imaging (MRI), metabolic screening, array-comparative genomic hybridization (CGH) and testing for mutations in CDKL5, STXBP1, and for ARX duplications. We found a probably pathogenic mutation in four patients. Missense mutations in SCN2A (p.Leu1342Pro) and KCNQ2 (p.Ala306Thr) were found in two patients with no history of epilepsy before the onset of ISs. The p.Asn107Ser missense mutation of ALG13 had been previously reported in four females with ISs. The fourth mutation was an in-frame deletion (p.Phe110del) in NR2F1, a gene whose mutations cause intellectual disability, epilepsy, and optic atrophy. In addition, we found a possibly pathogenic variant in KIF3C that encodes a kinesin expressed during neural development. Our results confirm that WES improves significantly the diagnosis yield in patients with sporadic ISs.

Altered MENIN expression disrupts the MAFA differentiation pathway in insulinoma

The protein MENIN is the product of the multiple endocrine neoplasia type I (MEN1) gene. Altered MENIN expression is one of the few events that are clearly associated with foregut neuroendocrine tumours (NETs), classical oncogenes or tumour suppressors being not involved. One of the current challenges is to understand how alteration of MENIN expression contributes to the development of these tumours. We hypothesised that MENIN might regulate factors maintaining endocrine-differentiated functions. We chose the insulinoma model, a paradigmatic example of well-differentiated pancreatic NETs, to study whether MENIN interferes with the expression of v-MAF musculoaponeurotic fibrosarcoma oncogene homologue A (MAFA), a master glucose-dependent transcription factor in differentiated β-cells. Immunohistochemical analysis of a series of human insulinomas revealed a correlated decrease in both MENIN and MAFA. Decreased MAFA expression resulting from targeted Men1 ablation was also consistently observed in mouse insulinomas. In vitro analyses using insulinoma cell lines showed that MENIN regulated MAFA protein and mRNA levels, and bound to Mafa promoter sequences. MENIN knockdown concomitantly decreased mRNA expression of both Mafa and β-cell differentiation markers (Ins1/2, Gck, Slc2a2 and Pdx1) and, in parallel, increased the proliferation rate of tumours as measured by bromodeoxyuridine incorporation. Interestingly, MAFA knockdown alone also increased proliferation rate but did not affect the expression of candidate proliferation genes regulated by MENIN. Finally, MENIN variants with missense mutations detected in patients with MEN1 lost the WT MENIN properties to regulate MAFA. Together, our findings unveil a previously unsuspected MENIN/MAFA connection regarding control of the β-cell differentiation/proliferation balance, which could contribute to tumorigenesis.

[Role of T lymphocyte cyclic nucleotides and G protein in sarcoidosis]

CD4+ T lymphocytes play a major role in the pathophysiology of sarcoidosis. Many studies have investigated the immunological and genetic abnormalities in this disease. There are few studies concerning the metabolic pathways. Essentially they concern the pathways: STAT1, MAPK38, NF-κB, Galphai, cAMP and cGMP PDE and PEMT1. Using studies in the literature and results of our own work concerning some metabolic aspects of T lymphocytes in sarcoidosis, we present a revue of the various hypotheses, which involve dysfunction of cAMP signaling pathways, such as RAS/RAF/MEK/ERK in T lymphocytes, leading to a disorder of immunity.

Screening of mutations in genes that predispose to hereditary paragangliomas and pheochromocytomas

Thirty per cent of the paragangliomas and pheochromocytomas reported are hereditary. Mutations in SDHB, SDHC, SDHD, and more recently SDHAF2 and TMEM127 genes have been described in these hereditary tumors. We looked for mutations in these 5 genes in a series of 269 patients with paragangliomas and/or pheochromocytomas. The SDHB, SDHC, and SDHD genes were analyzed in a series of 269 unrelated index patients with paragangliomas and/or pheochromocytomas using dHPLC screening of point mutations followed by direct sequencing and Multiplex PCR Liquid Chromatography to detect large rearrangements confirmed by quantitative PCR. In a second phase, we adapted Multiplex PCR Liquid Chromatography to the SDHAF2 and TMEM127 genes. This method and direct sequencing were applied to 230 patients without the SDHB, C, D mutations. Of the 269 patients, 44 carried a mutation (16.3%). Thirty-seven different mutations were identified: 18 in SDHB (including 2 large deletions), 8 in SDHD, 6 in SDHC, 5 in TMEM127, and no mutations in SDHAF2. Thirteen mutations have not been published so far. An exhaustive study of the different genes is needed to make possible a familial genetic diagnosis in paraganglioma and pheochromocytoma hereditary syndromes. Although mutations in SDHC and TMEM127 are less frequent than mutations in SDHB and SDHD, they also have less evident clinical feature indicators. Analyzing SDHAF2 must be restricted to familial extra-adrenal paragangliomas. Multiplex PCR Liquid Chromatography is a sensitive, fast, and inexpensive method for screening large rearrangements, which are infrequent in these syndromes.

[Genomic profiling by comparative genomic hybridization: analysis of ten enucleated uveal melanoma cases]

AIM

To detect major chromosomal aberrations from enucleated uveal melanoma and relate them to hepatic metastasis and survival.

PATIENTS AND METHODS

Ten uveal melanomas enucleated between 2005 and 2008 in the Lyon Croix-Rousse Hospital were retrospectively analyzed using a 19 000-clone comparative genomic hybridization microarray.

RESULTS

The most frequent imbalances were the loss of chromosome 3 (8/10), gain of the 8q arm (7/10) or the entire chromosome 8 (2/10), and gain of the 6p arm (2/10). Most metastatic tumors (6/7) and all cases of death (5/5) concerned melanoma with monosomy 3 and gain of the 8q arm.

DISCUSSION AND CONCLUSION

Genome-wide array comparative genomic hybridization is a reliable tool for identifying uveal melanoma genomic imbalances. Gains of the 8q arm with monosomy 3 are frequent and are strongly associated with poor outcome. Gains of the 6p arm are rare and have a better prognosis. There is a mutually exclusive relationship between monosomy 3 and chromosome 6 abnormalities in our study. These results confirm previously published reports.

Homozygous variant rs2076530 of BTNL2 and familial sarcoidosis

RATIONALE

Despite extensive studies, the pathogenesis of sarcoidosis is largely unknown. Although multiple environmental and putative infectious agents have been proposed, none was retained as a major contributor to the disease occurrence. Genetic predisposition to sarcoidosis was considered as a significant factor and numerous candidate genes have been reviewed. This last point was reinforced since the discovery of a pathogenic polymorphism (rs2076530 or G > A) of the BTNL2 gene, leading to an early truncation of the protein, which increases the relative risk of the disease. BTNL2 is known to act as a co-stimulatory molecule, inducing a negative signal to T-lymphocyte activation and the mutated gene is responsible for a truncated protein and disruption of membrane localization.

OBJECTIVES

Our work attempted to confirm this observation in a highly penetrant familial form of sarcoidosis.

RESULTS

In this family, the disease was diagnosed in 5 members through 3 generations. Despite individual clinical specificities, all displayed severe forms of the disease. Peripheral blood samples were collected from 3 patients and 2 additional healthy children of the fourth generation. Analysis of the BTNL2 gene confirmed the presence of the pathogenic variant of BTNL2 on both alleles (A/A homozygous genotype) in all subjects tested.

CONCLUSIONS

Our data suggest that the absence of a membrane anchored BTNL2 protein may increase genetic susceptibility to sarcoidosis and familial occurrence of the disease. This observation assessed the putative pathogenic involvement of the rs2076530 variant of BTNL2 in the development of this granulomatosis disease.

The syndrome of gastric carcinoid and hyperparathyroidism: a family study and literature review

OBJECTIVE

To present evidence supporting the hypothesis that the coexistence of gastric carcinoids (GCs) and hyperparathyroidism may represent a distinct clinical entity, not related to multiple endocrine neoplasia type 1 (MEN1).

METHODS

We studied a cohort of five young siblings (age range 26-42 years), one of whom had been found to have GC and hyperparathyroidism. All siblings underwent serial gastroscopies for the assessment of gastric neuroendocrine cell proliferations over a mean follow-up period of 31.2 months. Imaging, biochemical and hormonal as well as molecular genetic investigations were performed in the direction of MEN1 syndrome. The literature was searched for cases with coexistence of GCs and hyperparathyroidism not associated with MEN1.

RESULTS

Four of the siblings, all male, were found to have GCs in a background of Helicobacter pylori-associated chronic atrophic gastritis and pernicious anaemia, with no serological evidence of gastric autoimmunity. In two of them, asymptomatic hyperparathyroidism was also present. Screening for MEN1 gene mutations or large deletions was negative, and hormone and imaging investigations did not support a diagnosis of familial MEN1 syndrome. A literature search revealed sporadic reports of cases with GC and hyperparathyroidism not attributable to MEN1.

CONCLUSIONS

The association of GCs and hyperparathyroidism appears to constitute a distinct syndrome that can be encountered in genetically predisposed individuals, and should not be regarded as 'atypical' or 'incomplete' expression of MEN1. Its prevalence and aetiology should be the subject of future studies. Screening for hyperparathyroidism seems to be justified in patients with GC of any type.

Familial pituitary adenomas with a heterogeneous functional pattern: clinical and genetic features

Familial pituitary adenoma is a rare syndrome which may present either as isolated lesions, or in association with other endocrine tumors, for example in the frame of multiple endocrine neoplasia (MEN-1) or Carney complex (CNC). The most frequently described forms of familial isolated pituitary adenoma (FIPA) are familial somatotropinomas or prolactinomas. Recently, some cases of familial isolated somatotropinoma have been associated with germline mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene. The present report shows heterogeneous FIPA with 3 subtypes of tumor in 3 individuals of the same family: somatotropinoma in the proband, giant prolactinoma in a brother, and gonadotroph cell macroadenoma in the father. A prospective survey also suggested the occurrence of a silent microadenoma in the proband's sister. Clinical screening was performed in the 3 affected members, the 4th suspected case, and 9 additional, asymptomatic relatives. They had no clinical evidence of associated endocrine lesion suggesting MEN-1 or CNC. Genetic screening for germline mutation of the MEN-1, the gene encoding the protein kinase A (PKA) type 1 alpha regulatory subunit (R1 alpha) (PRKAR1alpha) and AIP gene was negative in 2 affected members. In conclusion, these data suggest that familial pituitary adenomas can occur with a heterogeneous functional pattern that is distinguished from MEN-1 or CNC. The absence of mutation of the recently described AIP gene suggests the implication of other predisposing gene(s). Collaborative, multicentric studies are needed to further define the location of gene(s) involved in heterogeneous FIPA.

Observatoire francophone des néoplasies endocriniennes multiples de type 1. Un outil du Groupe d'étude des Tumeurs Endocrines (GTE)

Wermer's syndrome or Multiple Endocrine Neoplasia Type-1 (MEN1) is an autosomal dominant inherited disease, related to mutations in MEN1, an approximately 10-kb gene encoding menin, localized on chromosome 11q13. The Endocrine Tumor Group (GTE) has set up a MEN1 observatory of 1001 regularly followed MEN1 cases. This observatory aims at registering and evaluating MEN1 cases in a large cohort. Any new study on a particular unexplored aspect of the disease may be proposed by a physician to the GTE. This article describes the way to diagnose a new MEN1 case and to register it. Procedures for participating in a new study are presented. Some original results are quoted.

Clinical characterization of familial isolated pituitary adenomas

CONTEXT

Familial pituitary adenomas occur rarely in the absence of multiple endocrine neoplasia type 1 (MEN1) and Carney complex (CNC).

OBJECTIVE

Our objective was to characterize the clinical and genealogical features of non-MEN1/CNC familial isolated pituitary adenomas (FIPA).

DESIGN AND SETTING

We conducted a retrospective study of clinical and genealogical characteristics of FIPA cases and performed a comparison with a sporadic population at 22 university hospitals in Belgium, Italy, France, and The Netherlands.

RESULTS

Sixty-four FIPA families including 138 affected individuals were identified [55 prolactinomas, 47 somatotropinomas, 28 nonsecreting adenomas (NS), and eight ACTH-secreting tumors]. Cases were MEN1/PRKAR1A-mutation negative. First-degree relationships predominated (75.6%) among affected individuals. A single tumor phenotype occurred in 30 families (homogeneous), and heterogeneous phenotypes occurred in 34 families. FIPA cases were younger at diagnosis than sporadic cases (P = 0.015); tumors were diagnosed earlier in the first vs. the second generation of multigenerational families. Macroadenomas were more frequent in heterogeneous vs. homogeneous FIPA families (P = 0.036). Prolactinomas from heterogeneous families were larger and had more frequent suprasellar extension (P = 0.004) than sporadic cases. Somatotropinomas occurred as isolated familial somatotropinoma cases and within heterogeneous FIPA families; isolated familial somatotropinoma cases represented 18% of FIPA cases and were younger at diagnosis than patients with sporadic somatotropinomas. Familial NS cases were younger at diagnosis (P = 0.03) and had more frequently invasive tumors (P = 0.024) than sporadic cases.

CONCLUSIONS

Homogeneous and heterogeneous expression of prolactinomas, somatotropinomas, NS, and Cushing's disease can occur within families in the absence of MEN1/CNC. FIPA and sporadic cases have differing clinical characteristics. FIPA may represent a novel endocrine neoplasia classification that requires further genetic characterization.

Génétique des tumeurs endocrines

Major advances have been made in the understanding of the genetic mechanisms underlying endocrine tumorigenesis, through the study of several syndromes of genetic predisposition and the identification of the genes involved. The syndrome of type 1 multiple endocrine neoplasia (MEN-1) is one of the best known; this autosomal dominant hereditary syndrome predisposes to the development of endocrine tumors of the pituitary, the parathyroids, the foregut and the adrenals. The responsible gene, known as MEN-1, encodes an original protein, menin, involved in several major cellular functions, such as the control of cell proliferation and differentiation. Type 2 multiple endocrine neoplasia (MEN-2) is an autosomal dominant hereditary syndrome associated with the development of medullary carcinomas of the thyroid, pheochromocytomas and hyperparathyroidism; the corresponding gene, RET, encodes a transmembrane receptor with tyrosine kinase activity. Endocrine tumors are also associated with non Hippel-Lindau disease and with phacomatoses, such as type 1 neurofibromatosis and tuberous sclerosis. Finally, isolated familial syndromes of endocrine tumors have been described: isolated familial hyperparathyroidism type II (HRPT2), associated with alterations in a gene coding for an original protein, parafibromin, or isolated familial syndromes of pheochromocytomas and paragangliomas (PRG) associated with mutations in the genes SDHB, SDHC or SDHD, which encode succinate-dehydrogenase subunits. The understanding of the genetic mechanisms underlying these syndromes of predisposition is essential for the diagnosis and management of these patients and their family; it also gives insight on the molecular mechanisms of endocrine tumorigenesis.

[Gastrinomas in multiple endocrine neoplasia type-1. A 127-case cohort study from the endocrine tumor group (ETG)]

On July 2000, 127 gastrinomas (31.1%) were studied by the Endocrine Tumour Group (GTE) using a 408-patient cohort of Multiple Endocrine Neoplasia Type 1 patients. The aim of this study was to assess clinical, biological, surgical data as well as their trends over three periods (<1980-1980/1989->1990). A Zollinger-Ellison syndrome (SZE) was present in 96% of the cases. Mean age at the onset of the disease was 39.4 years. There were 55.9% of men. Synchronous liver metastasis was present in 7.1%. Taken independently, the positivity of the four main diagnosis tests decreased over the time. The diagnosis of oesophagitis increased (4.5-29.7%), as well as the size of the resected tumours (9.9-16.8 mm). There was an increase in the familial background diagnosis (73.1-80%), an increasing use of Octreoscan scintigraphy and transduodenal ultrasound with positive detection of metastasis and tumours in 81.3% and 92.3%, respectively after 1991. Patients were operated on less frequently (96-52.5%), less frequently from the pancreas (87.5-37.5%), and from the gastro-intestinal tract (70.8-30%). The relative percentage of major pancreatic resections increased (with at least removal of the duodenum and the pancreatic head) (10-26.7%). The operative mortality disappeared. Six out of the seven patients (85.7%) who benefited from major pancreatic resections normalized their gastrine level postoperatively versus 15% in less radical techniques. Overall 5 years survival was 90 +/- 4.4%. Survival increased after 1985 (85 +/- 4.8% versus 95 +/- 3.6, P = 0.1).

CONCLUSION

SZE in NEM1 were diagnosed at an earlier stage and were less frequently operated on. Nevertheless, the incidence of synchronous metastasis did not change significantly. Patients were mainly operated on for gastric emergencies and pancreatic tumours in order to prevent metastasis without mortality after 1991.

[Multiple endocrine neoplasia type I or Werner syndrome. What is important to know about surgery of a rate disease]

Multiple endocrine neoplasia type 1 (MEN1) is a rare but misleading disease. The diagnosis is evocated when two main lesions are present (parathyroid, endocrine pancreas, pituary gland) but also when a family tree shows recurrent lesions. Other lesions must be taken into account (adrenal glands, neuroendocrine thymic or bronchic lesions, cutaneous lesions, lipomas, nervous central system tumors). Any surgical cure without knowing the MEN1 background leads to failure. Specific treatment of each lesion is reviewed. Genetic diagnosis is possible but the mutation is not found in all cases. Nevertheless, when the mutation is known in a family, a negative genetic test allows to exclude the disease. Prognosis is related to hepatic metastases and to thymic neuroendocrine tumors which are rare (2.1%) but aggressive. As a general rule, any apparently isolated endocrine lesion such hyperparathyroidism must prompt the surgeon to look for another endocrine lesion and to look for an abnormal family tree with recurent monoglandular or pluriglandular lesions.

Deregulation of genetic pathways in neuroendocrine tumors

Complexity and redundancy of functional pathways controlled by the human genome explain that a single type of tumor can be induced by independant defective mutations in various genes that encode proteins acting in different parts of the cell physiology. Neuroendocrine tumors represent a powerful model for understanding such a complexity from the fact that at least six unrelated genetic syndromes have been characterized in the last decade which predispose to endocrine cell proliferation with variable penetrance and expressivity. Multiple Endocrine Neoplasia, von Hippel-Lindau. Carney and uncommonly Recklinghausen and Tuberous Sclerosis syndromes represent almost the whole panel of genetic diseases for which genes have been cloned and most of the functional knowledge has been collected. All the endocrine glands are concerned in these diseases, but the cellular pathways that are deregulated downstream from the deleterious mutations occurring in the genes of these autosomal dominant syndromes. might be related to each step of the cell life, from mitosis to DNA transcription, membrane receptor signalling and growth factor production, protein catabolism and extracellular matrix synthesis, and from transcription regulation to apoptosis and response to hypoxia and cellular stress. Here, we present an overview of genes involved in genetic predisposition to neuroendocrine tumors and highlight the complexity of pathways involved and the need of further studies focussing on genes involved in tumoral progression, most neuroendocrine tumors being benign at initial diagnosis but able to produce highly malignant cellular clones related to secondary genetic alterations or deregulation of growth factor production or cell cell adhesion processes.

Hyperparathyroidism in multiple endocrine neoplasia type I: surgical trends and results of a 256-patient series from Groupe D'etude des Néoplasies Endocriniennes Multiples Study Group

The French and Belgian GENEM study group's multiple endocrine neoplasia type I (MEN-I) database was used to evaluate trends in clinical presentation, surgical treatment of primary hyperparathyroidism (pHPT) (n = 245), and prognostic factors for hypercalcemia correction among 256 MEN-I cases. The patients were retrieved through the GENEM network from various Belgian and French institutions with the help of genetics laboratories. Among the 245 pHPT patients (96%), 42% were men. The mean age at the time of diagnosis was 39.5 +/- 13.3 years. Trends were studied for three periods: before 1986, from 1986 to 1990, and thereafter. After 1990 MEN-I patients were more often diagnosed with isolated pHPT (8%, 11%, 28%, for the three periods, respectively; p = 0.002); it was seen more often in screened patients (31%, 28%, 53%; p = 0.001), more often among those in already known MEN-I families (64%, 45%, 72%; p = 0.005), and among those with lower preoperative calcemia (2.93, 2.87, 2.79 mmol/L; p = 0.001). The age at pHPT diagnosis remained constant throughout the study. The percentage of cervical explorations dropped during the entire study (87%, 87%, 53%; p < 0.0001). After 1985 the percentage of subtotal parathyroidectomies increased (25%, 59%, 51%; p = 0.0004). Pathology disclosed more hyperplasias (59%, 85%, 74%; p = 0.008). Postoperative hypercalcemia decreased (47%, 15%, 19%; p < 0.0001); and postoperative hypocalcemia increased nonsignificantly (5%, 15%, 15%; p = 0.1). Subtotal parathyroidectomy [odds ratio (OR) 13], no MEN-I family background (OR 3), and the most recent study period (> 1985) (OR 3) were significant predictive factors of hypercalcemia correction according to the multivariate analysis. This is the first multicentric study on the management of MEN-I-related pHPT. Immediate postoperative hHPT cure increased, but only 80% of the operated patients were cured after 1990. Fifteen percent were hypocalcemic. Because MEN-I-related hHPT cure remains difficult to achieve, we advocate that subtotal parathyroidectomies be performed in specialized centers.

Intestinal carcinoid tumours in a father and daughter

Familial cases of carcinoid tumours that are not associated with any known syndrome or disease are extremely rare. All cases reported in the world literature have involved carcinoid tumours of the gastrointestinal tract. Two cases of carcinoid tumours of the small intestine in a father and daughter are presented. Laboratory analyses did not support the hypothesis that the occurrence of carcinoid tumours in this family is a variant of the multiple endocrine neoplasia type 1 syndrome. A review of the literature on familial occurrence of intestinal carcinoid tumours in the absence of any other known carcinoid tumour-predisposing genetic syndrome is provided.

Cystic endocrine tumors of the pancreas: clinical, radiologic, and histopathologic features in 13 cases

Cystic endocrine tumors of the pancreas are rare and raise difficult clinical problems. Our aims were to reevaluate the diagnostic and therapeutic strategy and to assess their histopathologic characteristics. Thirteen cystic endocrine tumors diagnosed in 10 patients were included. Clinical, radiologic, and pathologic data were reviewed. There were 6 male and 4 female patients (median age, 46 yrs). Six patients had evidence of multiple endocrine neoplasia type 1 (MEN1) disease. Four had a functional endocrine syndrome. Ten tumors were visible on imaging studies. The most suggestive radiologic features were the existence of a peripheral hypervascular rim (10 cases) and images of cyst into cyst (two cases). On gross and histologic examinations, two distinct types were present. Macrocystic tumors (six cases) were unilocular and limited by a thick wall containing nests of tumor cells. Microcystic tumors (seven cases) were characterized by the presence of multiple cystic spaces directly lined by tumor cells. Surgical resection was performed in all cases. Three patients had lymph node metastases at the time of diagnosis. One patient is dead with metastatic dissemination. The others are alive without recurrence or metastasis. The diagnosis of endocrine tumor must be considered for any pancreatic cyst discovered in a patient with a history of MEN1 syndrome or with clinical features suggestive of this syndrome. Cystic pancreatic endocrine tumors must be treated by surgical resection because of their possible malignant evolution.

A malignant gastrointestinal stromal tumour in a patient with multiple endocrine neoplasia type 1

Loss of heterozygosity for polymorphic markers flanking the multiple endocrine neoplasia type 1 (MEN-1) gene in parathyroid and pancreatic islet tumours from subjects with MEN-1 has been well documented and has led to the hypothesis that the MEN-1 gene functions as a recessive tumour suppressor gene. We report a case of MEN-1 with duodeno-pancreatic gastrinoma, parathyroid hyperplasia, pituitary adenoma, adrenal adenoma, and lipomas, whose rare association with a malignant gastrointestinal stromal tumour (GIST) represents an undescribed combination. MEN-1 mutation in this family was shown as a frameshift (1607delA) in exon 10. To assess the role of the MEN-1 gene in the pathogenesis of tumours less commonly associated with MEN-1, we studied GIST DNA for loss of the unaffected MEN-1 gene allele. Stromal tumour and peripheral leucocyte DNAs from our patient were examined for loss of heterozygosity using the PYGM microsatellite polymorphism and an intragenic polymorphism (D418D in exon 9) in the MEN-1 gene. We showed no evidence for loss of the wild-type MEN-1 allele in GIST. The MEN-1 germline inactivating mutation 1607delA-ter558 in exon 10 was detected in the stromal tumour DNA, but no somatic mutation in the wild-type MEN-1 allele in GIST DNA was detected. Occurrence of GIST could be consistent with the possibility that this MEN-1-related uncommon neoplasm arose independently by a mechanism unrelated to the MEN-1 gene.

Molecular genetics of neuroendocrine tumors

Through insights into the molecular genetics of neuroendocrine tumors (NETs), the genes predisposing to multiple endocrine neoplasia (MEN) syndromes were identified. In MEN1, tumors occur in the parathyroids, endocrine pancreas, anterior pituitary, adrenal glands and thymic neuroendocrine tissues. The MEN1 gene encodes a putative growth-suppressor protein, menin, binding JunD, a transcriptional factor belonging to the AP-1 complex. However, new partners binding menin remain to be found. The MEN1 gene might be involved in 1-50% of sporadic NETs. Another critical mechanism involved in NETs is the deregulation of the RET-signalling pathways by oncogenic point mutations responsible for MEN2 syndromes. MEN2 refers to the inherited forms of medullary thyroid carcinoma. The RET proto-oncogene, a tyrosine-kinase receptor, is activated by missense mutations occurring either in the extracellular dimerization domain or intracellular tyrosine kinase catalytic regions. In both cases the receptor is constitutionally activated in the absence of natural ligands. Endocrine tumors also belong to the clinical pattern of Recklinghausen (NF1) and von Hippel-Lindau (VHL) diseases. The genes for both syndromes have been characterized and provide new pathways for endocrine tumorigenesis related to G-protein physiology (NF1) and transcriptional regulation and/or endothelial cell proliferation (VHL), respectively. Here, we propose a basic overview of recent data on genetic events leading a normal endocrine cell towards a fully malignant phenotype.

Malignant melanoma in patients with multiple endocrine neoplasia type 1 and involvement of the MEN1 gene in sporadic melanoma

Multiple endocrine neoplasia type 1 (MEN 1) is a familial cancer syndrome associated primarily with endocrine tumors of the parathyroids, enteropancreas and anterior pituitary. However, tumors of mesenchymal origin such as angiofibroma and collagenoma of the skin have also been associated with the syndrome. This highlights the possibility of an association between MEN 1 and some other types of tumors. Here we report 7 cases of primary malignant melanoma occurring in 7 MEN 1 families, all patients exhibiting classic features of MEN 1. Based on these findings and the previous implication of multiple melanoma tumor suppressor(s) in 11q, including the MEN1 region, we have investigated the involvement of the MEN1 gene in melanoma tumorigenesis. Mutation analysis was performed on a panel of 39 sporadic metastatic melanomas, 13 melanoma cell lines and 20 melanoma families without CDKN2A or CDK4 germline mutations. In addition, 19 sporadic metastatic tumors were screened for loss of heterozygosity (LOH) in 11q13. LOH was detected in 6 tumors (32%), and in 4 of the tumors the pattern of LOH suggested that the deletion included the MEN1 gene locus. A novel somatic nonsense mutation in exon 7 (Q349X) was identified in 1 sporadic tumor which also showed loss of the wild-type allele. We conclude that the MEN1 gene plays a role in the tumorigenesis of a small subgroup of melanoma.

Expression analysis of endogenous menin, the product of the multiple endocrine neoplasia type 1 gene, in cell lines and human tissues

We have investigated the endogenous expression of menin, a protein encoded by the gene mutated in multiple endocrine neoplasia type 1 (MEN1). Western blot analysis showed strong expression of menin as a 68 kDa protein in all of 7 human and primate cell lines tested. In a panel of 12 fetal human tissue extracts, 68 kDa menin was readily detected in brain cortex, kidney, pituitary, testis and thymus and weakly detected in thyroid. Reproducible bands other than 68 kDa were observed in adrenal and heart, whereas menin was undetectable in liver, lung, pancreas and skin. Analysis of synchronized HeLa cells revealed no variation in the amount or size of menin throughout the cell cycle. Protein expression was compared between lymphoblastoid cell lines from healthy controls and MEN1 patients carrying nonsense mutations on 1 allele. No truncated protein was detected in either cytoplasmic or nuclear fractions in mutation-carrying cells. The expression level and cellular location of full-length menin did not differ between cell lines derived from MEN1 patients and healthy donors. This suggests that the wild-type allele has been up-regulated in mutation-carrying cells to compensate for the loss of 1 functional allele.

[Insulinomas in multiple endocrine neoplasia type 1. Report of a series of 44 cases by the multiple endocrine neoplasia study group]

STUDY AIM

The aim of this retrospective study conducted by the "Groupe d'étude des néoplasies endocriniennes multiples type 1" (GENEM) was to report a series of insulinomas associated with multiple endocrine neoplasias type 1 (NEM 1) and to determine the most appropriate strategy for the topographical exploration and surgical management.

PATIENTS AND METHODS

From 1960 to 1996, 44 patients were included, 16 men and 28 women (mean age: 36.4 +/- 13.9 years). This study concerned morphological investigations, tumoral features, modalities and results of the treatment.

RESULTS

Insulinomas were associated with other functional islet tumors in 15 patients: ZE syndrome (n = 8), glucagonoma (n = 6), vipoma (n = 1). Malignant lesions were present in 6 patients: isolated insulinomas (n = 2), insulinomas associated with ZE syndrome (n = 2) and vipoma (n = 1). The sensitivity of the preoperative imaging procedures was less than 70%. Fourty-one patients were operated on: subtotal pancreatectomy (n = 26 including cephalic enucleations in 8), enucleations (n = 8), total pancreatectomy (n = 3), pancreaticoduodenectomy with caudal enucleations (n = 1), and for 3 patients, no details were available. There was no postoperative mortality. Hyperinsulinism disappeared in 27 patients (including 2 after reoperation) with a mean follow-up of 9 years. Among 6 patients with malignant lesions, 3 were alive with a 3, 4 and 10 year-follow-up.

CONCLUSION

Subtotal pancreatectomy with splenic conservation and enucleation of cephalic lesions is suggested as the procedure of choice in this group of patients. This procedure allows simplification of preoperative imaging investigations because lesions of the pancreatic head have only to be detected. Preoperative endoscopic ultrasonography and intraoperative ultrasonography are the best investigations.

A novel 9-base pair duplication in RET exon 8 in familial medullary thyroid carcinoma

Familial medullary thyroid carcinoma (FMTC) and multiple endocrine neoplasia type 2A syndromes are dominantly inherited diseases caused by activating germline mutations of the RET protooncogene. The majority of these patients carry a germline point mutation affecting one of five cysteine residues encoded by exon 10 (codon 609, 611, 618, or 620) or 11 (codon 634). In a few FMTC families, point mutations involving noncysteine codons in exon 13 (codons 768, 790, and 791), 14 (codon 804), or 15 (codon 891) have been reported. Hirschsprung's disease is a nonneoplastic disorder associated with RET mutations leading to a loss of function effect. Mutations are identified in 50% of the familial cases and are scattered along the gene. We now report the study of a FMTC family with four affected members and a history of fatal neonatal intestinal obstruction in the sister of the proband. Genetic analysis demonstrated the absence of an usual FMTC mutation and the presence of a germline 9-bp duplication in RET exon 8 in the heterozygous state in all patients with MTC. This new mutation creates an additional cysteine residue in the extracellular cysteine-rich domain of RET. Further studies are warranted to confirm whether this new mutation is causing MTC only or could be associated with Hirschsprung's disease.

[Clinicogenetic study of MEN1: recent physiopathological data and clinical applications. Study Group of Multiple Endocrine Neoplasia (GENEM)]

Multiple Endocrine Neoplasia type 1 (MEN1, OMIM 131100, Wermer syndrome) is characterized by inherited predisposition to primary hyperparathyroidism, endocrine pancreatic-duodenal, pituitary, adrenal glands tumors and benign and/or malignant proliferations of diffuse neuroendocrine tumors in thymus and bronchi, formerly defined as carcinoid tumors. Minor lesions have been observed in MEN1 patients such as cutaneous tumors (angiofibroma, lipoma, lentiginosis), thyroid epithelioma and tumors of the central nervous system, mainly spinal ependymoma. The MEN1 gene, a locus encompassing a 9 kb of genomic sequence contains 10 exons, the first exon being untranslated. The protein encoded by this gene was called menin and has been shown to contain two nuclear localization signals (NLS), suggesting a major function in the nucleus. Germline MEN1 mutations have been described in more than 150 families and are spread throughout the entire coding sequence. More than 70% of the mutations alter one or both NLS and no genotype-phenotype correlations were found to date. The MEN1 gene seems to be involved in a 20-30% of sporadic parathyroid and pancreatic/bronchic neuroendocrine tumors, but less than 1% of pituitary sporadic tumors. Further knowledge on the intracellular function of menin will be needed to understand the pathogenic effect of truncating and missense mutations of this gene in the initiation of endocrine cells tumorigenesis.

Characterization of the mouse Men1 gene and its expression during development

The gene responsible for multiple endocrine neoplasia type 1 (MEN1), a heritable predisposition to endocrine tumours in man, has recently been identified. Here we have characterized the murine homologue with regard to cDNA sequence, genomic structure, expression pattern and chromosomal localisation. The murine Men1 gene spans approximately 6.7 kb of genomic DNA and is comprised of 10 exons with similar genomic structure to the human locus. It was mapped to the pericentromeric region of mouse chromosome 19, which is conserved with the human 11q13 band where MEN1 is located. The predicted protein is 611 amino acids in length and overall is 97% homologous to the human orthologue. The 45 reported MEN1 mutations which alter or delete a single amino acid in human all occur at conserved residues, thereby supporting their functional significance. Two transcripts of approximately 3.2 and 2.8 kb were detected in both embryonal and adult murine tissues, resulting from alternative splicing of intron 1. By RNA in situ hybridization and Northern analysis the spatiotemporal expression pattern of Men1 was determined during mouse development. Men1 gene activity was detected already at gestational day 7. At embryonic day 14 expression was generally high throughout the embryo, while at day 17 the thymus, skeletal muscle, and CNS showed the strongest signal. In selected tissues from postnatal mouse Men1 was detected in all tissues analysed and was expressed at high levels in cerebral cortex, hippocampus, testis, and thymus. In brain the menin protein was detected mainly in nerve cell nuclei, whereas in testis it appeared perinuclear in spermatogonia. These results show that Men1 expression is not confined to organs affected in MEN1, suggesting that Men1 has a significant function in many different cell types including the CNS and testis.

Expression and chromosomal localization of the Requiem gene

Apoptosis in murine myeloid cell lines requires the expression of the Requiem gene, which encodes a putative zinc finger protein. We detected the protein in both cytoplasmic and nuclear subcellular fractions of murine myeloid cells and human K562 leukemia cells, which suggests that the protein might have a function distinct from a transcription factor. This distribution did not alter upon apoptosis induction by IL-3 deprivation. As an approach to investigate its role in development, we determined the spatio-temporal expression pattern in the mouse. Expression was detected in various tissues in earlier gestational age; however, confined to testes, spleen, thymus, and part of the hippocampus in the adult mouse. The expression profile is consistent with a functional role during rapid growth and cell turnover, and in agreement with a regulatory function for hematopoietic cells. The human cDNA clone sequenced showed high homology to its murine counterpart and extended the open reading frame by 20 codons upstream. The gene is located in the proximal region of mouse Chromosome (Chr) 19. In the homologous human region at 11q13, it is located at about 150 kb centromeric from MLK3.

Germ-line mutation analysis in patients with multiple endocrine neoplasia type 1 and related disorders

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant syndrome predisposing to tumors of the parathyroid, endocrine pancreas, anterior pituitary, adrenal glands, and diffuse neuroendocrine tissues. The MEN1 gene has been assigned, by linkage analysis and loss of heterozygosity, to chromosome 11q13 and recently has been identified by positional cloning. In this study, a total of 84 families and/or isolated patients with either MEN1 or MEN1-related inherited endocrine tumors were screened for MEN1 germ-line mutations, by heteroduplex and sequence analysis of the MEN1 gene-coding region and untranslated exon 1. Germ-line MEN1 alterations were identified in 47/54 (87%) MEN1 families, in 9/11 (82%) isolated MEN1 patients, and in only 6/19 (31.5%) atypical MEN1-related inherited cases. We characterized 52 distinct mutations in a total of 62 MEN1 germ-line alterations. Thirty-five of the 52 mutations were frameshifts and nonsense mutations predicted to encode for a truncated MEN1 protein. We identified eight missense mutations and five in-frame deletions over the entire coding sequence. Six mutations were observed more than once in familial MEN1. Haplotype analysis in families with identical mutations indicate that these occurrences reflected mainly independent mutational events. No MEN1 germ-line mutations were found in 7/54 (13%) MEN1 families, in 2/11 (18%) isolated MEN1 cases, in 13/19 (68. 5%) MEN1-related cases, and in a kindred with familial isolated hyperparathyroidism. Two hundred twenty gene carriers (167 affected and 53 unaffected) were identified. No evidence of genotype-phenotype correlation was found. Age-related penetrance was estimated to be >95% at age >30 years. Our results add to the diversity of MEN1 germ-line mutations and provide new tools in genetic screening of MEN1 and clinically related cases.

Thymic carcinoids in multiple endocrine neoplasia type 1

OBJECTIVE

To study the clinical, pathologic, and genetic features of thymic carcinoids in the setting of multiple endocrine neoplasia type 1 (MEN1) and to study means for detection and prevention of this tumor in patients with MEN1.

SUMMARY BACKGROUND DATA

Thymic carcinoid is a rare malignancy, with approximately 150 cases reported to date. It may be associated with MEN1 and carries a poor prognosis, with no effective treatment. Its underlying etiology is unknown.

METHODS

Ten patients with MEN1 from eight families with anterior mediastinal tumors were included in a case series study at tertiary referring hospitals. Clinicopathologic studies were done on these patients, with a review of the literature. Mutation analysis was performed on the MEN1 gene in families with clusterings of the tumor to look for genotype-phenotype correlation. Loss of heterozygosity was studied in seven cases to look for genetic abnormalities.

RESULTS

Histologic studies of all tumors were consistent with the diagnosis of thymic carcinoid. Clustering of this tumor was found in some of the families-three pairs of brothers and three families with first- or second-degree relatives who had thymic carcinoid. All patients described here were men, with a mean age at detection of 44 years (range 31 to 66). Most of the patients had chest pain or were asymptomatic; none had Cushing's or carcinoid syndrome. All tumors were detected by computed tomography (CT) or magnetic resonance imaging (MRI) of the chest. The results of octreoscans performed in three patients were all positive. Histopathologic studies were consistent with the diagnosis of thymic carcinoid and did not stain for ACTH. Mutation analysis of the families with clustering revealed mutations in different exons/introns of the MEN1 gene. Loss of heterozygosity (LOH) studies of seven tumors did not show LOH in the MEN1 region, but two tumors showed LOH in the 1p region.

CONCLUSIONS

MEN1-related thymic carcinoids constitute approximately 25% of all cases of thymic carcinoids. In patients with MEN1, this is an insidious tumor not associated with Cushing's or carcinoid syndrome. Local invasion, recurrence, and distant metastasis are common, with no known effective treatment. We propose that CT or MRI of the chest, as well as octreoscanning, should be considered as part of clinical screening in patients with MEN1. We also propose performing prophylactic thymectomy during subtotal or total parathyroidectomy on patients with MEN1 to reduce the risks of thymic carcinoid and recurrence of hyperparathyroidism. Its male predominance, the absence of LOH in the MEN1 region, clustering in close relatives, and the presence of different MEN1 mutations in these families suggest the involvement of modifying genes in addition to the MEN1 gene. A putative tumor suppressor gene in 1p may be involved.

A putative human zinc-finger gene (ZFPL1) on 11q13, highly conserved in the mouse and expressed in exocrine pancreas. The European Consortium on MEN 1

In the process of identification of the multiple endocrine neoplasia type 1 gene, which was recently published, we isolated a novel gene in the 11q13 region. This gene (named ZFPL1, for zinc-finger protein-like 1) is expressed strongly in the exocrine pancreas as a 1.4-kb polyadenylated RNA encoding a putative protein of 310 amino acids. A mouse EST contig predicts an equally sized murine protein with 91% amino acid sequence identity to the human protein. No significant homology with known proteins could be found through database screening. However, zinc-finger-like domains and leucine-zipper-like motifs in the predicted ZFPL1 protein were identified, suggesting the presence of DNA-binding and dimerization domains possibly involved in transcription regulation. This notion is supported by the presence of a putative bipartite nuclear localization signal. This paper presents the full-length cDNA sequence for this gene, its genomic structure and chromosomal orientation, and expression studies by Northern blot hybridization and RNA in situ hybridization.

Genetic testing in multiple endocrine neoplasia and related syndromes

Multiple Endocrine Neoplasia (MEN) syndromes are inherited diseases characterised by endocrine tumours occuring as autosomal dominant genetic diseases with high penetrance. In MEN1, most tumours affect the parathyroids, endocrine pancreas, anterior pituitary, and adrenal glands. The MEN1 gene has been cloned recently and encodes a nuclear protein without known function so far. More than 200 germline mutations have been identified in MEN1 patients throughout the entire coding sequence and no genotype-phenotype correlation has been found. Now, MEN1 gene screening is a powerful tool in pre-symptomatic diagnosis for MEN1 patients and those with inherited MEN1 related syndromes. MEN2 refers to the inherited forms of medullary thyroid carcinoma (MTC) which is associated with phaechromocytoma and parathyroid tumours in MEN2A, phaechromocytoma and mucosal neuromas in MEN2B. Familial isolated MTC is characterised by MTC only, and the three variants of MEN2 are related to germline missense mutations of the RET proto-oncogene, which encodes a tyrosine-kinase receptor. Germline RET mutations in MEN2 patients are related to the two main functionnal domains in the RET protein, the extracellular ligand binding domain (MEN2A and FMTC) and the intracellular catalytic domain (MEN2A, MEN2B and FMTC). Genotype-phenotype correlations have been established but must be used carefully in clinical practice. RET mutation analysis is now available for patients and prophylactic thyroidectomy in gene-carriers could be the most reliable way to cure the patients. Mechanisms of tumourigenesis induced by MEN2-related RET germline mutations have been analysed by in vitro studies and the generation of transgenic mice which develop true bilateral MTC. Recent insights on MEN syndrome pathogenesis and related inherited endocrine disorders have a major clinical impact and fundamental studies are now in progress in order to identify all genetic events leading from a normal endocrine tissue towards a fully malignant phenotype.

[Ethical recommendations for the genetic screening of hereditary endocrine diseases]

Predisposition to inherited diseases has been extensively studied over the last few years. Genetic studies have created a major concern about the psychological and ethical impact of risk evaluation in predisposed families. A significant number of inherited endocrine diseases are late-onset diseases and genetic risk assessment using molecular genetics leads to more accurate clinical and therapeutic follow-up of gene carriers. We describe minimal recommendations which could be associated to the official French laws published in July 1994 and analyze their concrete applications in clinical and genetic follow-up of patients and kindreds defined as gene carriers in predisposed families.

[Thymic and bronchial neuroendocrine tumors in multiple endocrine neoplasia type 1. GENEM1]

OBJECTIVES

Multiple endocrine neoplasia type 1 (MEN 1) mainly affects parathyroid glands, pancreatic islets and pituitary gland. The aim of this study in 95 MEN 1 patients was to examine less frequent localizations thymic and bronchic neuroendocrine tumors (NET).

PATIENTS AND METHODS

Two cases of bronchic NET were observed, both in women, and 4 cases of thymic NET, all in men, giving a prevalence of 7.3%. These NET were often asymptomatic. A metastatic diffusion was observed in 3 cases. Elevated plasma levels of glycoprotein hormone alpha subunit (SU) and FSH were observed in 3 and 1 cases respectively. Immunohistochemistry indicated the tumor cells to be frequently positively stained for HCG alpha and FSH.

DISCUSSION

We conclude that all patients with MEN 1 should undergo screening for thoracic NET, especially in high risk familial subgroups and in case of elevated plasma alpha SU or FSH.

[Identification of the gene associated with type 1 multiple endocrine neoplasia (NEM 1) susceptibility: a new pathway in the pathogenesis of neuro-endocrine tumors]

Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal dominant inherited disorder characterized by tumors of the parathyroids, endocrine pancreas, anterior pituitary, thymic, bronchic and digestive neuro-endocrine tissues and adrenal glands. The MEN1 gene has been recently cloned by two independent groups. The function of the protein encoded by the MEN1 gene is unknown until now. Germline mutations associated to the diseases in MEN1 families are distributed throughout all the open reading frame, suggesting the absence of founder effect. No consistent genotype-phenotype correlations have been yet recognized. Further studies on the functional domains of the MEN1 encoded protein could be useful to relate clinical expression of the disease with each type of mutation.

A large multiple endocrine neoplasia type 1 family with clinical expression suggestive of anticipation

We describe a large multigenerational multiple endocrine neoplasia Type 1 (MEN1) family with clinical expression suggestive of anticipation. In the second and third generations, two deceased obligate gene carriers died at the ages of 85 and 76 without the history of MEN1, whereas two other living gene carriers above the age of 65 have had no clinical evidence of MEN1 to date. In the fourth generation, eight members were affected, with four having severe MEN1-related and atypical malignancies: a case of metastatic endocrine pancreatic tumor, two cases of metastatic thymic carcinoids, and a case of spinal ependymoma. In the fifth generation, all five patients were below the age of 22 when the disease was detected. MEN1 was confirmed in the family by linkage analysis using MEN1-linked microsatellite markers and by identification of a nonsense mutation in the MEN1/menin gene. Alleotyping showed loss of heterozygosity (LOH) involving the wild-type alleles in seven tumors in the family including the ependymoma, which is the first MEN1-related case that shows genetic abnormality in chromosome 11q13, suggesting that MEN1 gene might be involved in the tumorigenesis of a subset of ependymomas. In relation to clinical anticipation, repeated expansion studies were carried out but failed to detect any expansion. We conclude that this is a unique MEN1 family and that an unknown genetic mechanism might be contributing to the anticipation phenomenon. We demonstrate in this family that all gene carriers, including the very young members, will need close and careful follow-up.