Novel MEN1 germline mutations in Brazilian families with multiple endocrine neoplasia type 1

OBJECTIVE: To characterize clinical features and identify MEN1 germline mutations in Brazilian families with multiple endocrine neoplasia type 1 (MEN1). Settings Non-profit academic centre. PATIENTS: Fourteen Brazilian families with MEN1 and 141 at-risk relatives. RESULTS: We identified 12 different MEN1 disease-causing mutations, seven of them previously unreported: 308delC; 375del21; 549A>T (I147F); 1243delA; 1348T>G (L413R); 1351T>C (L414P) and 1523G>T (W471C). Families with the recurrent mutations 360delTCTA and L413R were shown to be unrelated by mitochondrial-DNA and Y-chromosome haplotype analyses. Most of the MEN1 single point mutations involved evolutionarily conserved residues, whereas most of the deletion/frameshift changes occurred in GC-rich repetitive regions. Genetic screening of 141 at-risk family members identified 38 MEN1 mutation carriers, 37 (97.4%) of whom had at least one major MEN1-related tumour upon clinical investigation. CONCLUSIONS: High frequencies of MEN1 gene mutations were detected in Brazilian families with MEN1, including seven new genetic mutations that are predicted to cause inactivation of the MEN1 tumour suppressor gene. Our data underscore the need to implement a systematic MEN1 screening programme in Brazil.     

Novel germline mutations of the MEN1 gene in Greek families with multiple endocrine neoplasia type 1

Introduction  Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant hereditary disorder associated with mutations of the MEN1 gene and characterized by the combined occurrence of tumours of the parathyroid glands, the pancreatic islet cells and the anterior pituitary.
Aim  To identify MEN1 gene mutations and characterize clinical manifestations in Greek patients with MEN1.
Patients and methods  We studied four unrelated index patients with MEN1, 17 relatives and 100 control subjects. Among the relatives, seven were clinically and/or biochemically affected, while 10 were unaffected. DNA extraction, polymerase chain reaction (PCR) and direct sequencing of the MEN1 exons 2–10 and exon/intron boundaries were performed according to standard procedures.
Results  We identified novel MEN1 gene mutations in three out of four index patients (75%) and in all affected (100%) relatives. Novel mutations included: a frameshift mutation in exon 4 (c.684_685insG) at codon 229 (index patient A); a frameshift mutation in exon 8 (c.1160_1170dupAGGAGCGGCCG) involving codons 387–390 (index patient B); and a missense mutation in exon 4 (c.776T > C), which substitutes leucine with proline at codon 259 (L259P) (index patient C). In the fourth index patient, a common polymorphism (D418D) was detected.
Conclusions  This is the first report to reveal a high prevalence of novel MEN1 gene mutations among Greek MEN1 patients with apparent absence of genotype–phenotype correlation. Because of the small number of patients examined, the high prevalence detected might be a chance phenomenon.     

MEN1 gene mutations in Hungarian patients with multiple endocrine neoplasia type 1

OBJECTIVE: Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant hereditary disorder associated with mutations of the MEN1 gene. MEN1 may present as a familial or a sporadic disorder, with multiple endocrine tumours including parathyroid adenomas or hyperplasias, and pancreatic endocrine and pituitary gland tumours. The aim of this study was to examine the prevalence and spectrum of MEN1 gene mutations in Hungarian patients with familial and sporadic MEN1 and in those with a MEN1-related state. DESIGN: Mutation analysis, using temporal temperature gradient gel electrophoresis and direct sequencing of all coding exons and the corresponding exon-intron boundaries of the MEN1 gene, was performed. PATIENTS AND MEASUREMENTS: Peripheral blood DNA was obtained from 32 patients (19 index patients with familial or sporadic MEN1 and 13 index patients with familial or sporadic MEN1-related state). First degree relatives were also studied. RESULTS: Ten different MEN1 gene mutations were identified in 10 index patients, including four novel mutations (A91V, G28A and E26X all in exon 2, and L301R in exon 6). All but one mutation occurred in index patients with familial or sporadic MEN1; the prevalence of mutation was considerably higher in index patients with familial MEN1 (6/6 patients, 100%) than in those with sporadic MEN1 (3/13 patients, 23%). Of the 13 index patients with a MEN1-related state, only one patient with recurrent isolated primary hyperparathyroidism had a MEN1 gene mutation. Family screening indicated mutations in six symptomatic and in one asymptomatic first degree relative. CONCLUSION: These results confirm previous reports on the high prevalence of novel MEN1 gene mutations among patients with MEN1, and support the questionable efficacy of mutation screening in patients with sporadic MEN1-related states.     

Germline and somatic mutation of the gene for multiple endocrine neoplasia type 1 (MEN1)

Marx SJ, Agarwal SK, Kester MB, Heppner C, Kim YS, Emmert-Buck MR, Debelenko LV, Lubensky IA, Zhuang Z, Guru SC, Manickam P, Olufemi SE, Skarulis MC, Doppman JL, Alexander RH, Liotta LA, Collins FS, Chandrasekharappa SC, Spiegel AM, Burns AL (National Institutes of Health, Bethesda, USA). Germline and somatic mutation of the gene for multiple endocrine neoplasia type 1 ( MEN1 ) (Minisymposium: MEN & VHL). J Intern Med 1998; 243 : 447–53.
Dideoxyfingerprinting was used to screen for germline and somatic MEN1 mutations. This method, applied to a panel of germline DNA from 15 probands with multiple endocrine neoplasia type 1 (MEN-1), allowed confident discovery of the MEN1 gene. Germline MEN1 mutation has been found in 47 out of 50 probands with familial MEN-1, in 7 out of 8 cases with sporadic MEN-1, and in 1 out of 3 cases with atypical sporadic MEN-1. Germline MEN1 mutation was not found in any of five probands with familial hyperparathyroidism. Somatic MEN1 mutations were found in 7 out of 33 parathyroid tumours not associated with MEN-1. Allowing for repeating mutations, a total of 47 different germline or somatic MEN1 mutations have been identified. Most predict inactivation of the encoded 'menin' protein, supporting expectations that MEN1 is a tumour suppressor gene. The 16 observed missense mutations were distributed across the gene, suggesting that many domains are important to its as yet unknown functions.     

Effect of multiple endocrine neoplasia type 1 (MEN1) gene mutations on premature mortality in familial MEN1 syndrome with founder mutations

Estimation of mortality and the natural course of a disease is usually based on information of carefully studied individuals with or at risk for a specific disease. Genealogical information has rarely been accurate enough for such studies.With the help of church records and multiple endocrine neoplasia type 1 (MEN1) family information of the two founder MEN1 mutations in Northern Finland (1466del12 and 1657insC), we could trace back common ancestors born in the beginning of the 1700s (1466del12) and approximately 1850 (1657insC) and find 67 probable gene carriers born between 1728 and 1929, which were identified among their offspring. Information was gathered from 34 obligatory MEN1 gene carriers and 31 spouses. The mean age (+/- sd) of death of affected males (n = 16) was 61.1 +/- 12.0 yr vs. 65.8 +/- 15.3 yr for unaffected males (n = 16) and for affected females (n = 16) was 67.2 +/- 10.7 yr vs. 67.7 +/- 14.7 yr for unaffected females (n = 13). The ages of death of the obligatory heterozygotes did not differ from that of the spouses in sex groups or from the sex-matched life expectancy estimates derived from Finnish national statistics. Causes of death differed significantly between female probands and spouses. In conclusion, obligatory MEN1 gene carrier status did not show a harmful effect on survival in this retrospective analysis tracing back to almost 300 yr.     

Clinical features of multiple endocrine neoplasia type 1 (MEN1) phenocopy without germline MEN1 gene mutations: analysis of 20 Japanese sporadic cases with MEN1

OBJECTIVE: Multiple endocrine neoplasia type 1 (MEN1) is a familial tumour syndrome of endocrine tumours involving parathyroids, anterior pituitary and enteropancreatic neuroendocrine tissues, and is inherited in an autosomal dominant manner with high penetrance. Recently, the gene responsible for this syndrome, MEN1, was positionally cloned from chromosome 11q13. PATIENTS: To characterize sporadic MEN1 patients, we analysed the MEN1 gene by direct sequencing of the entire open reading frame from 20 individuals. RESULTS: We identified heterozygous germline mutations of the MEN1 gene in 8 of 20 (40%) cases. Seven were novel MEN1 germline mutations. Three mutations were splicing abnormalities, and all were confirmed to be splicing defects by RT-PCR. The clinical significance of detecting germline MEN1 mutations, not only in familial MEN1 but also in sporadic MEN1, was confirmed by the finding of asymptomatic mutant carriers among family members of the sporadic MEN1 patients. Seven of 8 cases with MEN1 mutations had enteropancreatic lesions in contrast to 4 of 12 (P < 0.018) in those cases with no mutation. Ten of the 12 cases without MEN1 mutation were more than 50-year-old. Six of these 10 cases had the same clinical features; primary hyperparathyroidism and a GH-secreting pituitary tumour. CONCLUSIONS: It is likely that the six cases without mutations were MEN1 phenocopies due to (i) two kinds of tumours with high natural incidence in older subjects developed by chance (ii) another familial tumour syndrome with low penetrance, e. g. familial acromegaly with primary hyperparathyroidism by mutation of another gene, or (iii) somatic mutation during early embryonic stages.     

Germline mutation of the multiple endocrine neoplasia type 1 (MEN1) gene in a family with primary hyperparathyroidism.

Familial primary hyperparathyroidism (FHP) is a rare hereditary disorder characterized by isolated parathyroid tumors without any other lesions related to multiple endocrine neoplasia (MEN). Primary hyperparathyroidism is usually expressed at an early age and is highly penetrated in MEN type 1 (MEN1), suggesting that some FHP may be a variant type or early stage of MEN1. The MEN1 gene has recently been cloned and its germline mutations have been considered to play an important role in the tumorigenesis of MEN1. We studied a Japanese family with primary hyperparathyroidism which included 4 patients. To investigate the possible relationship between primary hyperparathyroidism in this family and the MEN1 gene, we analyzed a proband for a germline mutation of the MEN1 gene in this study. We identified a novel heterozygous mutation (1350del3) at codon 414 in exon 9. Restriction digestion analysis revealed the same mutation pattern in his brother with hyperparathyroidism. These findings suggest that our patients may belong to a variant type of MEN1.     

Different phenotypes of multiple endocrine neoplasia type 1 (MEN1) in monozygotic twins found in a Japanese MEN1 family with MEN1 gene mutation

We report monozygotic twins who showed different MEN1 phenotypes. The proband (28 y.o., female) had both primary hyperparathyroidism (PHP) and insulinoma, and genetic analysis revealed a point mutation (569del1, exon 3) of the MEN1 gene. This mutation causes a frameshift and produces a stop codon at codon 184. Restriction digestion (HinfI) analysis confirmed the same mutation of the MEN1 gene in six of the affected members including her two sisters, the monozygotic twins, and no such mutation in two unaffected members. In two generations of this family, eight of eleven family members had PHP and four of them were found to have other MEN1-related lesions. Both of the monozygotic twins had PHP. Interestingly, one had pancreatic tumor but the other had no evidence of it. Pituitary MRI showed no pituitary lesion in either of them. This is the first Japanese case of monozygotic twins with different MEN1 phenotypes.     

Multiple endocrine neoplasia type 1 (MEN1) germline mutations in familial isolated primary hyperparathyroidism

BACKGROUND: Familial isolated hyperparathyroidism (FIHP) is an autosomal dominant disorder characterized by uniglandular or multiglandular parathyroid tumours that occur in the absence of other endocrine tumours. The disorder may represent either an early stage of multiple endocrine neoplasia type 1 (MEN1), or an allelic variant of MEN1, or a distinct entity involving another locus. We have explored these possibilities in seven families in whom primary hyperparathyroidism occurred as the sole endocrinopathy. METHODS: Seven FIHP families were ascertained and venous blood samples obtained from 35 members (17 affected and 18 unaffected) for DNA sequence analysis of the MEN1 gene. The mean (+/- SD) follow-up period in the 17 affected members was 15.06 (+/- 8.83) years. RESULTS: Four heterozygous germline mutations of the MEN1 gene were identified. These consisted of two 4-bp intragenic deletions that would result in prematurely truncated proteins, and two missense (Asp153Val and Ala411Pro) mutations. Furthermore, analysis of parathyroid tumour DNA from one individual revealed a loss of the wild-type allele and retention of the mutant allele, consistent with Knudson's 'two-hit' model of hereditary cancer and a tumour suppressor role for MEN1 in FIHP. CONCLUSIONS: Our results provide further support for FIHP being a distinct allelic variant of MEN1, and an analysis of the 16 mutations reported to date indicate that FIHP is associated with a higher frequency of missense MEN1 mutations.     

A novel germline mutation of multiple endocrine neoplasia type 1 (MEN1) gene in a Japanese MEN1 patient and her daughter.

Familial multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant inherited disorder characterized by tumors of the parathyroid, anterior pituitary and gastro-entero-pancreatic endocrine tissues. The MEN1 gene has recently been cloned and its germline mutations have been considered to play an important role in the tumorigenesis of MEN1. We analyzed a Japanese MEN1 patient and her daughter for germline mutations of the MEN1 gene. The proband (60 y.o.) had primary hyperparathyroidism (PHP) and gastrinoma, and her daughter (30 y.o.) had prolactinoma. Clinical examinations revealed no evidence of PHP in the daughter. We identified a novel heterozygous germline mutation (712 A del) at codon 201 in exon 3 of the MEN1 gene in the proband. Restriction digestion analysis revealed the same mutation pattern in her daughter. These findings suggest that this family has familial MEN1 including a rare case of MEN1 with a single lesion of the pituitary. Genetic examinations are useful as diagnostic tools for any rare or variant case of familial MEN1.     

MEN1 gene mutation analysis in Italian patients with multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN 1) is a familial syndrome characterized by parathyroid, enteropancreatic and pituitary tumors. The gene responsible for this syndrome is localized at chromosomal 11q13 region and DNA markers from this region cosegregate with the disease. The recent identification of the MEN1 gene, encoding for a protein termed menin of 610 amino acids, allowed mutational screening to be performed both in affected families and sporadic cases. To date many different heterozygous mutations, spreading across all the encoding sequence, have been identified in MEN 1 patients with no apparent mutational hot spots or genotype-phenotype correlation. To analyze the genetic alterations of the MEN1 gene occurring in Italian patients we performed mutational screening by Denaturant Gradient Gel Electrophoresis followed by sequencing of exons 2-10 of the MEN1 gene in 27 Italian MEN 1 families and in five sporadic cases. We identified 17 different heterozygous mutations in 60% of analyzed cases. Twelve of these mutations are novel. Two mutations each occurred twice in unrelated families but no evidence of genotype-phenotype correlation can be established for these families. The extension of genetic diagnosis to asymptomatic family members allowed the identification of 10 MEN1 mutant gene carriers, one newly described and nine previously detected by linkage analysis with DNA markers from the 11q13 region. Our findings add new information to the diversity of mutations occurring in the MEN1 gene and confirm that the mutational screening of MEN 1 is a useful approach to detect individuals at higher risk of developing MEN 1-associated tumors.     

Characteristics of the Danish families with multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN1) is caused by autosomal dominantly inherited mutations in the MEN1 gene. Here, we report 25 MEN1 mutations - of which 12 are novel - found in 36 Danish families with MEN1 or variant MEN1 disease. Furthermore, one FIHP family was found to have an earlier reported mutation. The mutations were predominantly found in exons 9 and 10 encoding the C-terminal part of menin. Seven of the mutations were missense mutations, changing conserved residues. Furthermore screening of 93 out of 153 consecutive patients with primary hyperparathyroidism (pHPT) identified five mutation carriers. Two of these belonged to known MEN1 families, whereas the only MEN1-related disease in the other three was pHPT. Screening of 96 consecutive patients with fore-/midgut endocrine tumours revealed five mutation carries out of 28 patients with sporadic gastrinomas, whereas no mutations were found in 68 patients with other fore-/midgut endocrine tumours. Moreover, screening of 60 consecutive patients with primary prolactinoma did not identify any mutation carriers. Our data indicate that MEN1 mutation screening is efficient in patients with familial MEN1. Screening should also be offered to patients with pHPT or gastrinomas after thorough investigation into the family history. In contrast, sporadic carcinoid tumours or primary prolactinomas are rarely associated with germ-line MEN1 mutations.