Joseph J. Shepherd

CLINICOPATHOLOGIC STUDIES OF THYMIC CARCINOIDS IN MULTIPLE ENDOCRINE NEOPLASIA TYPE 1

&NA; Abbreviations used in this article: ACTH, adrenocorticotropic hormone; CT, computed tomography; LOH, loss of heterozygosity; MEN, multiple endocrine neoplasia; MRI, magnetic resonance imaging; NSE, neuron‐specific enolase.

Predictive testing for multiple endocrine neoplasia type 1 using DNA polymorphisms.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominantly inherited predisposition to neoplastic lesions of the parathyroids, pancreas, and the pituitary. We have previously located the predisposing genetic defect to the long arm of chromosome 11 by genetic linkage. In this study, 124 members of six MEN1 families, including 59 affected individuals, were genotyped for restriction fragment length polymorphisms with different DNA probes, and the genetic linkage between these marker systems and MEN1 was determined. 13 marker systems (17 DNA probes) were found to be linked to MEN1. These markers are located within a region on chromosome 11 spanning 14% meiotic recombinations, with the MEN1 locus in the middle. Four of the marker systems are on the centromeric side of MEN1, and four on the telomeric side, based on meiotic crossovers. The remaining five DNA probes are closely linked to MEN1, with no crossovers in our set of families. The 13 marker systems can be used for an accurate and reliable premorbid test for MEN1. In most clinical situations it is possible to identify a haplotype of this part of chromosome 11 with the mutant MEN1 allele in the middle. The calculated predictive accuracy is greater than 99.5% if three such marker systems are informative. Therefore, genetic linkage testing can be used for informed genetic counseling in MEN1 families, and to avoid unnecessary biochemical screening programs.

Phenotype and phenocopy: the relationship between genotype and clinical phenotype in a single large family with multiple endocrine neoplasia type 1 (MEN 1).

The majority of reports describing the natural history and prognosis of multiple endocrine neoplasia type 1 (MEN 1) utilize phenotypic rather than molecular genetic criteria to establish a diagnosis of MEN 1.

Malignant thymic carcinoid is not prevented by transcervical thymectomy in multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal dominant tumour syndrome. It is characterized by primary hyperparathyroidism, pituitary neoplasia and foregut lineage neuroendocrine neoplasia. Malignant thymic carcinoid tumours are an uncommon but important manifestation of MEN 1. Transcervical thymectomy is often advocated as prophylaxis against thymic carcinoids, although there is a paucity of evidence to support the efficacy of this procedure. This is the first report of a malignant thymic carcinoid occurring in an MEN 1 patient following prior parathyroidectomy and transcervical thymectomy. It is concluded that transcervical thymectomy does not reliably provide prophylaxis against thymic carcinoid.

Identification of somatic mutations of the MEN1 gene in sporadic endocrine tumours

Endocrine tumours of the pancreas, anterior pituitary or parathyroids arise either sporadically in the general population, or as a part of inherited syndromes such as multiple endocrine neoplasia type 1 (MEN 1). The mechanisms responsible for the development of sporadic endocrine lesions are not well understood, although loss of heterozygosity (LOH) of the MEN1 locus on chromosome 11q13 and somatic mutation of the MEN1 gene have been frequently associated with the development of MEN 1-type sporadic endocrine lesions. To further investigate the role of the MEN1 gene in sporadic endocrine tumorigenesis, we analysed DNA from 14 primary parathyroid lesions, 8 anterior pituitary tumours and 3 pancreatic tumours for the presence of somatic MEN1 gene mutations and LOH of seven microsatellite markers flanking the MEN1 locus. In addition, we similarly analysed 8 secondary parathyroid lesions which arose in patients with chronic renal failure. None of the patients studied had a family history of MEN 1. Three primary parathyroid lesions and one pancreatic tumour (glucagonoma) were found to have lost one allele at the MEN1 locus. Somatic mutations were identified by SSCP and sequence analysis in one of these parathyroid lesions (P320L) and in the glucagonoma (E179V). These results support previous findings that inactivation of the MEN1 tumour suppressor gene contributes to the development of sporadic MEN 1-type endocrine lesions but is not associated with the development of parathyroid hyperplasia seen in some renal failure patients.

Enteropancreatic malignancy associated with multiple endocrine neoplasia type 1

Enteropancreatic malignancy is an important cause of morbidity and mortality associated with multiple endocrine neoplasia type 1 (MEN 1). However, the risk factors and mechanisms of the tumorigenesis of this malignancy are poorly understood.

Exclusion of the 13-kDa rapamycin binding protein gene (FKBP2) as a candidate gene for multiple endocrine neoplasia type 1

The MEN1 gene is considered to be a tumour suppressor gene and has been localised to a 1-Mb region of 11q13.1. In this study, we report the physical localisation of the 13-kDa FK506 and rapamycin binding protein gene (FKBP2) to the cosmid marker D11S750, which is located inside the MEN1 region of non-recombination. The product of this gene is involved in signal transduction and is thus a candidate cell growth regulator or tumour suppressor gene. Northern studies have revealed that FKBP2 is expressed in those tissues predisposed to hyperplasia in MEN1; however, single-strand conformation polymorphism analysis and direct sequencing of DNAs from affected members of MEN1 kindreds and sporadic tumour DNAs have been performed and no mutations have been found. These studies exclude FKBP2 as a candidate gene for MEN1.

Clonal loss of INT-2 alleles in sporadic and familial pancreatic endocrine tumours

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Octreotide improves biochemical, radiologic, and symptomatic indices of gastroenteropancreatic neoplasia in patients with multiple endocrine neoplasia type 1 (MEN‐1)

Multiple endocrine neoplasia type 1 (MEN‐1) is an autosomal dominant tumor syndrome associated with parathyroid, gastroenteropancreatic (GEP), and pituitary neoplasia. Gastrinoma and GEP malignancy are common life‐threatening endocrine complications of MEN‐1. An effective management strategy for these disorders remains to be determined. The authors attempted to determine the role of the somatostatin analogue, octreotide, in ameliorating features of hypergastrinemic GEP neoplasia associated with MEN‐1.

Genetic mapping of the multiple endocrine neoplasia type 1 locus at 11q13

Abstract. Oncogenesis of tumours related to multiple endocrine neoplasia type 1 (MEN1) is associated with somatic deletions involving the MEN1 locus at chromosomal region 11q13, suggesting inactivation of a tumour‐suppressor gene in this region. Here we describe the localization of the MEN1 gene to a 900‐kb region, based on linkage analysis in affected families and deletion mapping of MEN1‐associated tumours. In addition, a set of microsatellite markers mapped to the 11q11–13 region were used for linkage analysis in a large Tasmanian MEN1 pedigree, demonstrating the usefulness of these markers for presymptomatic testing in affected families.