Multiple endocrine neoplasia type 1 is not rare in Japan

VIPoma with multiple endocrine neoplasia type 1 identified as an atypical gene mutation

A 47-year-old man presented with persistent diarrhoea and hypokalaemia. CT revealed 4 pancreatic tumours that appeared to be VIPomas, because the patient had an elevated plasma vasoactive intestinal polypeptide level. MRI showed a low-intensity area in the pituitary suggestive of a pituitary tumour, and a parathyroid tumour was detected by ultrasonography and 99Tc-MIBI scintigraphy. Given these results, the patient was diagnosed with multiple endocrine neoplasia type 1 (MEN1) and scheduled for surgery. MEN1 is an autosomal dominant disorder associated with MEN1 mutations. Genetic testing indicated that the patient had a MEN1 gene mutation; his 2 sons had the same mutations. Most MEN1 tumours are benign, but some pancreatic and thymic tumours could become malignant. Without treatment, such tumours would result in earlier mortality. Despite its rarity, we should perform genetic testing for family members of patients with MEN1 to identify mutation carriers and improve the patients' prognosis.

Multiple endocrine neoplasia type 1 in Japan: establishment and analysis of a multicentre database

OBJECTIVE

Multiple endocrine neoplasia type 1 (MEN1) is less well recognized in Asian countries, including Japan, than in the West. The clinical features and optimal management of MEN1 have yet to be clarified in Japan. The aim of this study was to clarify the clinical features of Japanese patients with MEN1.

DESIGN/PATIENTS

We established a MEN study group designated the 'MEN Consortium of Japan' in 2008, and asked physicians and surgeons to provide clinical and genetic information on patients they had treated. Of 680 registered patients, 560 were analysed.

MEASUREMENTS

Clinical and genetic features of Japanese patients with MEN1 were examined.

RESULTS

Primary hyperparathyroidism, gastroenteropancreatic neuroendocrine tumours (GEPNET), and pituitary tumours were seen in 94·4%, 58·6% and 49·6% of patients, respectively. The prevalence of insulinoma was higher in the Japanese than in the West (22%vs 10%). In addition, 37% of patients with thymic carcinoids were women, while most were men in western countries. The MEN1 mutation positive rate was 91·7% in familial cases and only 49·3% in sporadic cases. Eight novel mutations were identified. Despite the availability of genetic testing for MEN1, the application of genetic testing, especially presymptomatic diagnosis for at-risk family members appeared to be insufficient.

CONCLUSIONS

We established the first extensive database for Asian patients with MEN1. Although the clinical features of Japanese patients were similar to those in western countries, there were several characteristic differences between them.

Delay in the diagnosis of multiple endocrine neoplasia type 1: typical symptoms are frequently overlooked

The morbidity and mortality of individuals with multiple endocrine neoplasia type 1 (MEN1) can be reduced by early diagnosis of MEN1 and related endocrine tumors. To find factors contributing to early diagnosis, we collected clinical information on MEN1 patients through a MEN study group, "MEN Consortium of Japan" and analyzed the time of initial symptom-dependent detection of parathyroid tumors, gastro-entero-pancreatic neuroendocrine tumors (GEPNETs) and pituitary tumors, and that of tumor detection-dependent MEN1 diagnosis in 560 patients. Main tumors were identified up to 7.0 years after symptoms appeared and there was no difference in age at the diagnosis of GEPNETs alone between probands and family members. In patients with typical symptoms (peptic ulcers, urolithiasis, fasting hypoglycemia, bone fracture/loss and amenorrhea), the mean interval between symptom manifestation and tumor detection was extended up to 9.6 years. In particular, 21.7% (5/23) of patients with amenorrhea were diagnosed with pituitary tumors in under one year. In patients with peptic ulcers (from parathyroid tumors or GEPNETs) and urolithiasis (from parathyroid tumors), the interval was positively correlated with age at tumor detection. The interval between tumor detection and MEN1 diagnosis was also prolonged to approximately four years in patients with fasting hypoglycemia (from GEPNETs) and amenorrhea. A substantial delay in the diagnosis of symptom-related tumors and subsequent MEN1 and inadequate screening of GEPNETs in family members were indicated. A greater understanding of MEN1 may assist medical practitioners to make earlier diagnoses, to share patients' medical information and to give family members sufficient disease information.

Clinical and genetic features of patients with multiple endocrine tumors who have neither family history nor MEN1 germline mutations

Multiple endocrine neoplasia type 1 (MEN1) is an hereditary tumor syndrome that involves specific endocrine organs such as parathyroids, anterior pituitary gland, and endocrine pancreas. The responsible gene for this syndrome, MEN1, has been isolated and that enabled genetic diagnosis for patients with endocrine tumors and early detection of asymptomatic gene carriers in affected families. Nevertheless, there are a considerable number of patients with MEN1 who have neither family history nor germline MEN1 mutations. In this article, clinical features of such patients are described. Among 53 MEN1 patients we have seen during the last 20 yr, five patients who did not have either MEN1 germline mutation or family history were categorized as MEN1 phenocopy. During the same period, we have also experienced three patients who had primary hyperparathyroidism and adrenocortical tumor but had no apparent family history of endocrine tumors. These patients were considered as MEN1 phenocopy variants and included in the study. The mean age of MEN1 phenocopy patients (including variants) at diagnosis was 48 yr, which was not significantly different from that of probands of familial MEN1 (46 yr) who carry heterozygous MEN1 gene mutations. In the majority of MEN1 phenocopy patients, primary hyperparathyroidism was due to a single parathyroid adenoma. In contrast to a previous report, we found that MEN1 phenocopy patients are not necessarily older than probands of familial MEN1. Phenotypic expression of such patients is variable, thus differentiation of familial MEN1 and MEN1 phenocopy cannot be made based on age and clinical phenotype alone.

Pituitary adenomas in adolescent patients with multiple endocrine neoplasia type 1

Two juvenile patients with multiple endocrine neoplasia type 1 (MEN1) who developed pituitary adenomas are reported. The first case, a 14-year-old girl, developed prolactinoma and manifested delayed puberty and growth arrest. The second case, a 16-year-old boy, was asymptomatic and a pituitary adenoma accompanied by mild elevation of PRL and GH was identified through family screening. His growth and pubertal development was not impaired. Medication with bromocriptine was started for both cases with good therapeutic responses. These cases emphasize relevance of early screening of endocrine disorders for members of families with MEN1.

Analysis of the MEN1 gene in sporadic pituitary adenomas from Japanese patients

An autosomal-dominant syndrome known as multiple endocrine neoplasia type 1 (MEN1) is characterized by tumors in parathyroid glands, pancreatic endocrine tissues and the anterior pituitary gland. The predisposing gene was identified at 11q13 when germline mutations in the MEN1 gene were detected in affected pedigrees. To investigate a possible role of this gene in tumorigenesis of non-familial pituitary adenomas, we examined 24 sporadic tumors from Japanese patients for loss of heterozygosity (LOH) at the 11q13 region and for somatic mutations in the entire coding region and exon-intron boundaries of MEN1. Although three common sequence variants were detected, none of the tumors exhibited either LOH or somatic mutations of this gene. Our results indicate that inherited and sporadic forms of pituitary adenomas are different in terms of the genetic events that contribute to their development, and that other loci associated with pituitary neoplasia must still be sought.

Multiple endocrine neoplasia type 1 concomitant with Prader-Willi syndrome: case report and genetic diagnosis

A case of multiple endocrine neoplasia type 1 (MEN 1) accompanied with Prader-Willi syndrome (PWS) was reported. Diagnosis of both diseases have been genetically confirmed. Delay in the diagnosis and management for PWS made surgery for endocrine tumors difficult. This is the first report on the concomitance of MEN 1 with PWS.