Multiple endocrine neoplasia type 1 is a rare genetic neuroendocrine syndrome caused by over 1500 different germline mutations. It can cause 20 different endocrine tumors affecting primarily the parathyroid glands, gastroenteropancreatic tract, and the anterior pituitary gland. Multiple endocrine neoplasia type 2A (MEN2A) and Multiple endocrine neoplasia type 2B (MEN2B) are autosomal dominant genetic syndromes because of a germline variant in the \'rearranged during transfection\' (RET) proto-oncogene. There are common RET mutations causing receptor hyperactivation and induction of downstream signals that cause oncogenesis. Common conditions with MEN2A are medullary thyroid cancer (MTC), pheochromocytoma, and primary hyperparathyroidism. Common conditions with MEN2B include MTC, pheochromocytomas, and benign ganglioneuromas.

OBJECTIVE: No genomic data have been put forth that prove beyond a shadow of doubt that sporadic medullary thyroid cancer (MTC) occurs in infancy, childhood, and/or adolescence.
METHODS: This was a retrospective comparative study of consecutive patients with MTC who had neck surgery at a tertiary center over a 30-year period.
RESULTS: Included were 1252 patients with MTC (337 hereditary and 915 sporadic), of whom 107 (8.5%) were operated before the age of 18 yrs. Only 4 (3.7%) of the 107 pediatric patients, aged 14, 16, 17 and 17 years, had sporadic MTC. These 4 patients, 3 of whom had been referred for completion surgery, revealed much larger thyroid tumors (medians of 20 mm vs. 1.5-5 mm) than the 103 pediatric patients with hereditary MTC. As for extrathyroid extension and nodal metastases, the 4 patients with sporadic MTC were more comparable to the 37 carriers of highest-risk mutations, 31 (84%) of whom were index patients with de novo disease, than to the 66 carriers of high-risk, intermediate-risk, or low-risk RET mutations (25-38% vs. 0-8%, and medians of 9-9.5 vs. 0 node metastases after dissection of more (medians of 72-91.5 vs. 4.5-9) nodes).
CONCLUSIONS: Sporadic MTC, arising rarely, if ever, below the age of 14 years, is exceptional in infancy and childhood, and infrequent in adolescence. At diagnosis, it is almost as widely metastatic as hereditary MTC of the highest-risk category which almost always, like sporadic MTC, presents as de novo disease.

Medullary thyroid carcinoma (MTC) accounts for only 3% of all thyroid carcinomas: 75% as sporadic MTC (sMTC) and 25% as hereditary MTC (hMTC) in the context of multiple endocrine neoplasia type 2 (MEN2). Early diagnosis is possible by determining the tumour marker calcitonin (Ctn) when clarifying nodular goitre and by detecting the mutation in the proto-oncogene RET in the MEN2 families. If the Ctn level is only slightly elevated, up to 30 pg/ml in women and up to 60 pg/ml in men, follow-up checks are advisable. At higher levels, surgery should be considered; at a level of > 100 pg/ml, surgery is always advisable. The treatment of choice is total thyroidectomy, possibly with central lymphadenectomy. In the early stage, cure is possible with adequate surgery; in the late stage, treatment with tyrosine kinase inhibitors is an option. RET A mutation analysis should be performed on all patients with MTC. During follow-up, a biochemical distinction is made between: healed (Ctn not measurably low), biochemically incomplete (Ctn increased without tumour detection) and structural tumour detection (metastases on imaging). After MTC surgery, the following results should be available for classification in follow-up care: (i) histology, Ctn immunohistology if necessary, (ii) classification according to the pTNM scheme, (iii) the result of the RET analysis for categorisation into the hereditary or sporadic variant and (iiii) the postoperative Ctn value. Tumour progression is determined by assessing the Ctn doubling time and the RECIST criteria on imaging. In most cases, \"active surveillance\" is possible. In the case of progression and symptoms, the following applies: local (palliative surgery, radiotherapy) before systemic (tyrosine kinase inhibitors).

BACKGROUND: Multiple endocrine neoplasia type 2 (MEN2) is a rare, autosomal dominant endocrine disease. Currently, the RET proto-oncogene is the only gene implicated in MEN2A pathogenesis. Once an RET carrier is detected, family members should be screened to enable early detection of medullary thyroid carcinoma, pheochromocytoma, and hyperparatitity. Among these, medullary thyroid carcinoma is the main factor responsible for patient mortality. Accordingly, delineating strategies to inform clinical follow-up and treatment plans based on genes is paramount for clinical practitioners.
METHODS: Herein, we present RET proto-oncogene mutations, clinical characteristics, and treatment strategies in a family with MEN2A. A family study was conducted on patients diagnosed with MEN2A. DNA was extracted from the peripheral blood of family members, and first-generation exon sequencing of the RET proto-oncogene was conducted. The C634Y mutation was identified in three family members spanning three generations. Two patients were sequentially diagnosed with pheochromocytomas and bilateral medullary thyroid carcinomas. A 9-year-old child harboring the gene mutation was diagnosed with medullary thyroid carcinoma. Surgical resection of the tumors was performed. All family members were advised to undergo complete genetic testing related to the C634Y mutation, and the corresponding treatments administered based on test results and associated clinical guidelines.
CONCLUSIONS: Advancements in MEN2A research are important for familial management, assessment of medullary thyroid cancer invasive risk, and deciding surgical timing.

Medullary thyroid cancer (MTC) is the most frequent manifestation of multiple endocrine neoplasia type 2 (MEN2) that determines the oncological outcome. Germline mutations in the rearranged during transfection (RET) protooncogene, a tumor suppressor gene on chromosome 10q11.2, were identified 30 years ago as the genetic basis of MEN2 and published in 1993 and 1994. These seminal findings gave rise to the concept of prophylactic thyroidectomy for asymptomatic gene mutation carriers based on a positive RET gene test, which has become the standard of care ever since. Clinical genetic investigations showed genotype-phenotype correlations with respect to the individual gene mutation regarding the penetrance and onset of MTC and to a lesser extent also with respect to the other components of MEN2, pheochromocytoma and primary hyperparathyroidism. From this a clinically relevant risk stratification could be derived. Initially, the optimal timing of prophylactic thyroidectomy was primarily based on the RET genotype alone, which was not sufficient for a precise age recommendation and subsequently required additional consideration of calcitonin serum levels for fine tuning. Calcitonin levels first show the risk of lymph node metastasis when they exceed the upper normal limit of the assay independent of carrier age and RET mutation. Routine calcitonin screening of patients with nodular thyroid disease, screening of families on identification of MEN2 index patients, and pre-emptive thyroidectomy in carriers of gene mutations with normal calcitonin levels have led to the fact that nowadays, 30 years after the first description of the gene mutations causing the disease, the life-threatening hereditary MTC has become curable: a shining example for the success of translational transnational medical research for the benefit of patients.
UNASSIGNED: Das medulläre Schilddrüsenkarzinom (MTC) ist die häufigste das onkologische Outcome bestimmende Manifestation der multiplen endokrinen Neoplasie (MEN) Typ 2. Vor 30 Jahren konnten die Keimbahnmutationen im RET(REarranged-during-Transfection)-Protoonkogen, einem Tumorsuppressorgen auf Chromosom 10q11.2, als Ursache der MEN2 identifiziert und 1993 und 1994 erstveröffentlicht werden. Hieraus entwickelte sich das Konzept der prophylaktischen Thyreoidektomie für asymptomatische Genmutationsträger, das seither Therapiestandard ist. Klinisch-genetische Untersuchungen zeigten hinsichtlich der individuellen Genmutation eine Genotyp-Phänotyp-Korrelation sowohl hinsichtlich der Penetranz und des Entstehungszeitraums des MTC und in geringerem Ausmaß auch hinsichtlich der anderen MEN2-Komponenten Phäochromozytom und primärer Hyperparathyreoidismus. Daraus konnte eine klinisch relevante Risikostratifizierung abgeleitet werden. Die allein genotypbasierte, aber nicht hinreichend genaue Altersempfehlung für den besten Zeitpunkt der prophylaktischen Thyreoidektomie wurde in der Folgezeit durch Kombination des RET-Genotyps mit dem Kalzitoninwert präzisiert, der mutations- und altersunabhängig erst bei Überschreiten des oberen Kalzitoninnormwertes das Risiko einer Lymphknotenmetastasierung anzeigt. Die routinemäßige Kalzitoninbestimmung bei Knotenstrumen, das Familienscreening bei MEN2-Indexpatienten und die karzinompräventive prophylaktische Thyreoidektomie bei normokalzitoninämischen Genmutationsträgern haben dazu geführt, dass heute, 30 Jahre nach der Erstbeschreibung der krankheitsverursachenden Genmutationen, das lebensbedrohende hereditäre MTC heilbar geworden ist: ein leuchtendes Beispiel für den Erfolg translational transnationaler medizinischer Forschung zum Wohl der Betroffenen.

BACKGROUND: In clinical practice, genetic testing has become standard for many cancerous diseases. While a diagnosis of a single hereditary syndrome is not uncommon, the coexistence of two genetic diseases, even with partially common symptoms, remains unusual. Therefore, targeted next-generation sequencing (NGS), along with genetic consultation and imaging studies, is essential for every patient with confirmed paraganglioma. In this report, we present two sisters diagnosed with multiple endocrine neoplasia type 2 (MEN2A) and familial paraganglioma syndrome type 1 (FPGL1).
METHODS: After presenting to the clinic with neck tumors persisting for several months, both patients underwent tumor removal procedures following imaging and laboratory studies. Pathological reports confirmed the diagnosis of paragangliomas. Subsequently, genetic testing, including NGS, revealed a mutation in the rearranged during transfection (RET) gene: the heterozygous change (c.2410G > A), (p.Val804Met), and a variant of the succinate dehydrogenase complex subunit D (SDHD) gene: (c.64 C > T), (p.Arg22Ter). Subsequently, thyroidectomy procedures were scheduled in both cases.
CONCLUSIONS: To the best of our knowledge, this is the first report presenting these two mutations in two related patients, resulting in distinctive genetic syndromes with similar manifestations. This underscores that although infrequent, multiple hereditary disorders may co-occur in the same individual.

The age-specific development of the three constituent components of multiple endocrine neoplasia type 2 (MEN 2) is incompletely characterized for many of the >30 causative rearranged during transfection (RET) mutations, which this genetic association study aimed to specify. Included in the study were 683 carriers of heterogeneous RET germline mutations: 53 carriers with 1 highest-risk mutation (codon 918); 240 carriers with 8 different high-risk mutations (codon 634); 176 carriers with 16 different intermediate-risk mutations (codon 609, 611, 618, 620, or 630); and 214 carriers with 6 different low-risk mutations (codon 768, 790, 804, or 891).There was a strong genotype-specific development of MEN 2 constituent components, with distinct age gradients from C cell disease to node negative medullary thyroid cancer (MTC), from node negative to node positive MTC, from node positive MTC to pheochromocytoma, and from pheochromocytoma to primary hyperparathyroidism. Primary hyperparathyroidism was not observed among the 53 MEN 2B patients who carried highest-risk mutations (age range: 0.5-50 years), of whom no more than 12 (23%) and 3 (6%) carriers were older than age 30 years and 35 years, respectively. The age-specific development of MTC differed significantly between the four RET risk categories, whereas the age-specific development of pheochromocytoma differed significantly only between the two strongest RET risk categories. No significant differences were noted in the development of primary hyperparathyroidism. These findings delineate age-specific disease manifestation corridors for the three constituent components of MEN 2 by RET genotype. These corridors are useful for initial risk assessment and organ-specific surveillance of newly identified RET carriers going forward.

Very early onset inflammatory bowel disease (VEOIBD) is a rare entity in pediatrics. Its association with primary immunodeficiencies of monogenic origin is known. We present the case of a patient diagnosed with VEOIBD who underwent massive paralleled exome sequencing. The result of the study showed a pathogenic variant in the RET proto-oncogene, associated with multiple endocrine neoplasia type 2A disease. There are no previous reports of association of RET proto-oncogene variants with VEOIBD. The presence of these two clinical entities cannot be attributed to a single genetic cause.
La enfermedad inflamatoria intestinal de inicio muy temprano (VEOIBD) es una entidad rara en pediatría. Es conocida su asociación con inmunodeficiencias primarias de origen monogénico. Presentamos el caso de una paciente con diagnóstico de VEOIBD a quien se le realizó una secuenciación masiva del exoma. El resultado del estudio permitió identificar una variante patogénica en el proto oncogen RET, asociada con enfermedad neoplasia endocrina múltiple tipo 2A. No hay reportes de asociación de variantes en el proto oncogen RET con VEOIBD. No se puede adjudicar la presencia de estas dos entidades clínicas a una única causa genética.

The report covers the current and past activities of the department Molecular Genetics-Function and Therapy (MGFT) at the Cyprus Institute of Neurology and Genetics (CING), an affiliated Reference Center for the European Reference Network on Rare Endocrine Conditions (Endo-ERN).The presented data is the outcome of > 15 years long standing collaboration between MGFT and endocrine specialists from the local government hospitals and the private sector. Up-to-date > 2000 genetic tests have been performed for the diagnosis of inherited rare endocrine disorders. The major clinical entities included Congenital Adrenal Hyperplasia (CAH) due to pathogenic variants in CYP21A2 gene and Multiple Endocrine Neoplasia (MEN) type 2 due to pathogenic variants in the RET proto-oncogene. Other rare and novel pathogenic variants in ANOS1, WDR11, FGFR1, RNF216, and CHD7 genes were also found in patients with Congenital Hypogonadotropic Hypogonadism. Interestingly, a few patients with Disorders of Sexual Differentiation (DSD) shared rare pathogenic variants in the SRD5A2, HSD17B3 and HSD3B2 while patients with Glucose and Insulin Homeostasis carried theirs in GCK and HNF1A genes. Lastly, MGFT over the last few years has established an esteemed diagnostic and research program on premature puberty with emphasis on the implication of MKRN3 gene on the onset of the disease and the identification of other prognosis biomarkers.As an Endo-ERN member MGFT department belongs to this large European network and holds the same humanistic ideals which aim toward the improvements of health care for patients with rare endocrine conditions in respect to improved and faster diagnosis.

BACKGROUND: Homozygous mutations, 2 identical gene versions (alleles), 1 from each biological parent, are exceptional. Clinical descriptions of affected families, comprising few carriers only, are scattered throughout the literature, hindering evidence generation.
METHODS: Included in this literature analysis were 5 RET families with ≥1 homozygous carrier and ≥3 heterozygous carriers per family.
RESULTS: In consanguineous families with first-degree cousins, homozygotes presented with node-positive medullary thyroid cancer and pheochromocytoma in their mid-teens, whereas heterozygotes presented in their end-30s and early 40s. Homozygotes developed node-positive medullary thyroid cancer 27.4 years and pheochromocytoma 23 years earlier than heterozygotes. These age differences were smaller in the 15 families carrying founder mutation p.Leu666delinsAsnSer, whereas homozygotes developed node-positive medullary thyroid cancer in their mid-40s, 6 years earlier than heterozygotes in their early 50s.
CONCLUSIONS: These results, limited in scope and size and modulated by extent of consanguinity, are consistent with moderate dose-response effects accelerating MEN2A development.