RET proto-oncogene genetic screening of families with multiple endocrine neoplasia type 2 optimizes diagnostic and clinical management in China

Simultaneous bilateral laparoscopic cortical-sparing adrenalectomy for bilateral pheochromocytomas in multiple endocrine neoplasia type 2

Purpose

This study aimed to assess the feasibility of synchronous bilateral laparoscopic or open cortical-sparing adrenalectomy (SB-LCSA or SB-OCSA) for bilateral pheochromocytomas (bPHEOs) in multiple endocrine neoplasia type 2 (MEN2).

Methods

Altogether, 31 patients (54.8% were women) were diagnosed with MEN2-related bPHEOs, and 29 of them underwent varying specific adrenalectomies. We systematically analyzed and evaluated their clinical profiles, mutation types, tumor histopathological features, and follow-up records.

Results

All 31 patients with bPHEOs presented with RET-C634 (90.3%) and RET-M918T (9.7%) mutations, and the median age at initial presentation was 38 years (range, 23-78). bPHEOs were synchronous in 27 patients and metachronous in 4 (12.9%) patients. In total, 29 patients underwent initial cortical-sparing adrenalectomy (CSA) including 23 (79.3%) undergoing synchronous bilateral CSA (18 SB-LCSA and 5 SB-OCSA) and 6 (20.7%) undergoing metachronous CSA. SB-LCSA and synchronous surgery were associated with less bleeding volume and shorter length of hospital stay than SB-OCSA and metachronous surgery (all P's < 0.05). Corticosteroid replacement treatment was necessary for 14 patients (45.2%) after bilateral CSA. During a median follow-up period of 7 years (range, 1.8-23), three of these patients (10.3%) had a recurrent disease that required reoperation.

Conclusion

SB-LCSA is feasible for treating synchronous bPHEOs and should be recommended as a prioritized surgical approach.

Medullary Thyroid Carcinoma and Associated Endocrinopathies in Slovenia from 1995 to 2021

Background: Medullary thyroid cancer (MTC) is a rare endocrine tumour that is sporadic in 75% of cases and occurs as a part of inherited cancer syndromes in approximately 25% of cases. The aim of this study was to determine the frequency and type of RET pathogenic variants (PVs) in the Slovenian MTC patient population diagnosed between 1995 and 2021 and to elucidate the full range of associated endocrinopathies. Methods: A retrospective analysis of medical records of 266 MTC patients and their relatives seen in a tertiary centre between 1995 and 2021 was performed. Sequence analysis of exons 10, 11, 13, 14, 15, and 16 of the RET gene was analysed in most patients using Sanger sequencing. From 2017, the entire sequence of RET gene was analysed in most patients using targeted next-generation sequencing. Results: Germline PVs in the RET proto-oncogene were identified in 21.6% probands from 21 different MTC families. Of their tested relatives, 65% (67/103) were RET-positive and 35% (36/103) were RET-negative. PVs were detected in codon 618 and codon 634 in 28.6%, and in codon 790 in 23.8%. The RET-positive group consisted of 52 MTC patients, 13 patients with C cell hyperplasia and 2 individuals with neither. Associated endocrinopathies were diagnosed in 8/21 families: primary hyperparathyroidism (PHPT) in six families and pheochromocytoma (PHEO) in five families. In 62% of RET-positive families (13/21), no associated endocrinopathies were diagnosed. PHEO was most commonly associated with C634R (6/13) and PHPT with C634R (4/7). Hirschsprung’s disease appeared in one patient with RET PV in codon 618. Based on data from the Cancer Registry of Republic of Slovenia, only individual cases of common cancers with well understood environmental risk factors were discovered; lung cancer in 2/21 of families, papillary thyroid cancer in 3/21 of families, cutaneous melanoma in 2/21 of families, cervical cancer in 1/21 families, and lymphoma in 1/21 families. Conclusions: Analysis of prospectively collected MTC cases during a 27-year period revealed that 21.6% of Slovenian patients are RET PV carriers. Sixty-two percent of families had none of the associated endocrinopathies, confirming the thesis that FMTC is the most common presentation. This could suggest using risk-stratified management approaches when screening for PHEO and PHPT in RET PV carriers. However, more studies are needed to evaluate potential genetic risk modifiers as well as safety, improved quality of life, and medical cost reduction in the case of a patient-oriented approach.

Impact of RET Screening on the Management of Multiple Endocrine Neoplasia Type 2A: 10 Years Experience and Follow-up in Three Families

BACKGROUND

Multiple endocrine neoplasia type 2A (MEN 2A) is mainly caused by germline RET codon C634 mutation and is characterized by medullary thyroid carcinoma (MTC), pheochromocytoma (PHEO), and hyperparathyroidism (HPTH). The early diagnosis and initial normative treatment are helpful for the long-term outcome of MEN2A.

METHODS

Three index cases and their 29 relatives from three families with MEN2A were included in this study. Genetic screening was performed on all participants. Demographic, clinical profiles, tumor histopathologic features, and follow-up records were systematically analyzed.

RESULTS

In total, RET C634Y mutation was identified in 10 individuals (10/32, 31.3%). Among them, 5 presented with MTC symptoms, whereas the other 5 did not show apparent clinical manifestation, and all were subjected to thyroidectomy with varying neck dissection. Compared to individuals in the former, the latter benefited greatly from RET screening with significantly younger age at diagnosis of MTC and surgery (18.1 ± 13.8 years vs. 39.0 ± 14.1 years, P =0.045), and less-aggressive MTC behavior (size: 0.74 vs. 2.82 cm, P =0.026; LN+/resected: 20.0% vs. 100.0%, P =0.048) and also lower recurrence rate of MTC (20.0% vs. 100.0%, P =0.048). The PHEO was identified in 6 of the 10 carriers (60.0%), and all had undergone adrenal-sparing surgery. During the 10 years of follow-up, one (16.7%) developed recurrence of PHEO.

CONCLUSION

Integrated RET screening, serum calcitonin, and plasma metanephrine/normetanephrine levels can facilitate the early diagnosis and standardized MTC/PHEO surgery to improve the prognosis of MEN2A. Laparoscopic adrenal-sparing surgery prior to the bilateral total thyroidectomy is a preferred surgical approach for PHEO.

Spectrum of Germline RET variants identified by targeted sequencing and associated Multiple Endocrine Neoplasia type 2 susceptibility in China

Background

Germline RET mutations and variants are involved in development of multiple endocrine neoplasia type 2 (MEN2). The present study investigated a spectrum of RET variants, analyzed genotype-phenotype relationships, and evaluated their effect on the MEN2 phenotype in Han Chinese patients.

Methods

Targeted sequencing detected germline RET variants in 697 individuals, including 245 MEN2, 120 sporadic medullary thyroid cancer (MTC), and 15 pheochromocytoma (PHEO) patients and their 493 relatives. In silico analyses and classifications following ACMG-2015 were performed. Demographic, clinical variant types, and endocrine neoplasia molecular diagnosis records were also analyzed.

Results

Nineteen different RET mutations (18 point and 1 del/ins mutations) in 214 patients with MEN2A (97.7%) or MEN2B (2.3%) were found, of which exon 11/10 mutations accounted for 79% (169/214). Nineteen compound mutations were found in 31 patients with MEN2A. Twenty-three variants (18 single and 5 double base substitution/compound variants) non-classification were also found. Of these, 17 (3 of pathogenic, 10 of uncertain significance, 2 of likely benign and 2 as benign) were found in 31 patients with MTC/PHEO. The remaining 6 variants (4 of uncertain significance and 2 of likely benign) found in 8 carriers had no evidence of MEN2. The entire cohort showed MEN2A-related PHEO, all occurring in exons 11/10, particularly at C634. Kaplan-Meier curves showed age-dependent penetration rates of MTC and PHEO, and occurrence rates of PHEO in patients with exon 11 mutations were all higher than those within exon 10; these bilateral PHEO were always associated with exon 11 mutations (all P < 0.05). While patient offspring had PHEO, parents with MEN2A had none, the frequency was approximately 10%. Interestingly, at least 6.8% of families were adoptive. Also, 3 non-hotspot RET variants (R114H, T278N, and D489N) appeared with high frequency. Conversely, polymorphism S836S was absent.

Conclusions

These data are largely consistent with current evidence-based recommendations in the clinical practice guidelines. Diversity of RET variants or carriers may involve a different natural disease course. Further large-scale targeted sequencing studies will serve as an accurate and cost-effective approach to investigating MEN2 genotype-phenotype correlations for discovery of rare or unknown variants of RET.

Multiple Endocrine Neoplasia Type 2B Associated Mixed Medullary and Follicular Thyroid Carcinoma in A Chinese Patient with RET M918T Germline Mutation

BACKGROUND

Mixed medullary and follicular thyroid carcinoma (MMFC) displays heterogeneous morphological components and immunophenotypical features intermingled within the same lesion, which is rare and most described in the sporadic form. We report herein a Chinese patient with multiple endocrine neoplasia type 2B (MEN2B) harboring germline RET M918T and associated MMFC.

METHODS

A case of a 39-year-old male patient with MEN2B presented palpable neck masses in both thyroid lobes (maximum sizes: left, 3.9 cm; right, 5.4 cm) and a definitive phenotype. Serum levels of calcitonin (Ctn; >2000pg/mL), carcinoembryonic antigen (CEA; 719.27ng/mL), and thyroglobulin (Tg; 98.54ng/mL) were high. Fine-needle aspiration cytology showed features positive for malignancy, suggesting the possibility of medullary thyroid carcinoma (MTC). Total thyroidectomy, along with extending bilateral neck lymph nodes dissection, and subsequently, genetics family screening were performed.

RESULTS

The histopathological examination yielded a diagnosis of MMFC that showed immunohistochemical characteristic patterns of the component of MTC positive for Ctn and CEA, chromogranin A, and the follicular carcinoma components were positive for Tg. Lymph node metastasis was observed showing medullary tumoral cells positive for Ctn and follicular-like structures lacking tumor cells positive for Tg staining (T4bN1bM0). Genetics screening confirmed RET M918T (c.2753T>C) mutation manifested in the patient but was not detected in other family members. Follow up showed that the serum Ctn, CEA and Tg levels respectively dropped to 54.38pg/ml, 4.16ng/mL and 0.04ng/mL 16 months after the surgery.

CONCLUSION

Particular and diverse patterns of MMFC should be recognized with immunostaining features. MMFC occurring in a patient with MEN2B harboring RET M918T may be unique biological behavior and the treatment is mostly radical surgery.

5P Strategies for Management of Multiple Endocrine Neoplasia Type 2: A Paradigm of Precision Medicine

Multiple endocrine neoplasia type 2 (MEN2) is a neuroendocrine cancer syndrome characterized by medullary thyroid carcinoma, in combination or not with pheochromocytoma, hyperparathyroidism, and extra-endocrine features. MEN2 syndrome includes two clinically distinct forms subtyped as MEN2A and MEN2B. Nearly all MEN2 cases are caused by germline mutations of the RET proto-oncogene. In this review, we propose "5P" strategies for management of MEN2: prevention, prediction, personalization, psychological support, and participation, which could effectively improve clinical outcomes of patients. Based on RET mutations, MEN2 could be prevented through prenatal diagnosis or preimplantation genetic testing. Identification of pathogenic mutations in RET can enable early diagnosis of MEN2. Combining RET mutation testing with measurement of serum calcitonin, plasma or urinary metanephrine/normetanephrine, and serum parathyroid hormone levels could allow risk stratification and accurately prediction of MEN2 progression, thus facilitating implementation of personalized precision treatments to increase disease-free survival and overall survival. Furthermore, increased awareness of MEN2 is needed, which requires participation of physicians, patients, family members, and related organizations. Psychological support is also important for patients with MEN2 to promote comprehensive management of MEN2 symptoms. The "5P" strategies for management of MEN2 represent a typical clinical example of precision medicine. These strategies could effectively improve the health of MEN2 patient, and avoid adverse outcomes, including death and major morbidity, from MEN2.

RET S409Y Germline Mutation and Associated Medullary Thyroid Carcinoma

Background: Inherited medullary thyroid carcinoma (MTC) is primarily caused by RET mutations that are commonly localized in exons 5, 8, 10, 11, and 13-16. In this study, we report pedigrees for individuals with MTC that harbor a germline S409Y variant within exon 6 of the RET proto-oncogene. Methods: Targeted sequencing was used to diagnose four apparently sporadic MTC index cases carrying the germline RET S409Y (c.1226 C>A) variant. Subsequently, 27 relatives of these individuals underwent clinical and genetic assessments and/or thyroid surgery. Furthermore, in silico analyses and in vitro assays were performed to predict or verify the potential oncogenic activity of the S409Y variant. Results: Overall, 15 of 31 participants were found to carry the RET S409Y variant. Of these, 6 presented with isolated MTC (mean age 50.2 years; range 41-75 years), of which 3 presented with neck lymph node metastases and 2 presented with distant liver or lung metastases. Among the remaining 9 carriers, 3 (mean age 56 years; range 41-76 years) had elevated serum calcium-stimulated calcitonin (sCtn) or concurrent marginally elevated serum calcitonin (Ctn) levels, whereas the other 6 (mean age 37.5 years; range 14-52 years) exhibited typical Ctn/sCtn levels (p < 0.05). None of the 15 carriers in these 4 families presented clinical evidence of pheochromocytoma, hyperparathyroidism, or Hirschsprung's disease. In silico analyses revealed that S409Y was a "possibly damaging" mutation that could affect the RET protein inter-domain interface. An in vitro assay revealed that the phosphorylation level of RET tyrosine 905 was relatively higher in the RET S409Y mutant than in wild-type (WT) RET. Moreover, transfection of HEK 293 cells with S409Y enhanced the phosphorylation activity of AKT, ERK pathways, and it increased cell proliferation compared with WT RET, but to a lesser degree than that for the RET C618Y and C634Y mutations. Conclusions: This study demonstrates that the novel germline RET S409Y variant is likely pathogenic and is associated with lower penetrance of MTC than that for the C618Y and C634Y mutations. Individuals with S409Y should be managed using a personalized approach, and additionally, "at-risk" family members should be evaluated. Additional studies are needed to elucidate the correlation between the S409Y mutation and multiple endocrine neoplasia type 2-specific tumors.

A pioneering RET genetic screening study in the State of Ceará, Brazil, evaluating patients with medullary thyroid cancer and at-risk relatives: experience with 247 individuals

OBJECTIVE

Initial diagnosis of medullary thyroid carcinoma (MTC) is frequently associated with advanced stages and a poor prognosis. Thus, the need for earlier diagnoses and detection in relatives at risk for the disease has led to increased use of RET genetic screening.

SUBJECTS AND METHODS

We performed RET screening in 247 subjects who were referred to the Brazilian Research Consortium for Multiple Endocrine Neoplasia (BRASMEN) Center in the State of Ceará. Direct genetic sequencing was used to analyze exons 8, 10, 11, and 13-16 in MTC index cases and specific exons in at risk relatives. Afterward, clinical follow-up was offered to all the patients with MTC and their affected relatives.

RESULTS

RET screening was performed in 60 MTC index patients and 187 at-risk family members. At the initial clinical assessment of the index patients, 54 (90%) were diagnosed with apparently sporadic disease and 6 (10%) diagnosed with hereditary disease. After RET screening, we found that 31 (52%) index patients had sporadic disease, and 29 (48%) had hereditary disease. Regarding at-risk relatives, 73/187 were mutation carriers. Mutations in RET codon 804 and the rare p.M918V mutation were the most prevalent.

CONCLUSIONS

Performing RET screening in Ceará allowed us to identify a different mutation profile in this region compared with other areas. RET screening also enabled the diagnosis of a significant number of hereditary MTC patients who were initially classified as sporadic disease patients and benefited their relatives, who were unaware of the risks and the consequences of bearing a RET mutation.

Clinical Syndromes and Genetic Screening Strategies of Pheochromocytoma and Paraganglioma

Pheochromocytomas (PCCs) are rare neuroendocrine tumors that originate from chromaffin cells of the adrenal medulla, and paragangliomas (PGLs) are extra-adrenal pheochromocytomas. These can be mainly found in clinical syndromes including multiple endocrine neoplasia (MEN), von Hippel–Lindau (VHL) syndrome, neurofibromatosis-1 (NF-1) and familial paraganglioma (FPGL). PCCs and PGLs are thought to have the highest degree of heritability among human tumors, and it has been estimated that 60% of the patients have genetic abnormalities. This review provides an overview of the clinical syndrome and the genetic screening strategies of PCCs and PGLs. Comprehensive screening principles and strategies, along with specific screening based on clinical symptoms, biochemical tests and immunohistochemistry, are discussed.

The RET C611Y mutation causes MEN 2A and associated cutaneous

BACKGROUND

Cutaneous lichen amyloidosis (CLA) has been reported in some multiple endocrine neoplasia type 2A (MEN 2A) families affected by specific germline RET mutations C634F/G/R/W/Y or V804M, as a characteristic of the clinical manifestation in ‘MEN 2A with CLA’, one of four variants of MEN 2A, which was strictly located in the scapular region of the upper back.

PATIENT FINDINGS

This study reports a large south-eastern Chinese pedigree with 17 individuals carrying the MEN 2A-harboring germline C611Y (c.1832G>A) RET mutation by Sanger sequencing. One individual presented MEN 2A-related clinical features, including typical CLA in the interscapular region; another individual exhibited neurological pruritus and scratching in the upper back but lacked CLA skin lesions. Both subjects presented with CLA or pruritic symptoms several years before the onset of medullary thyroid carcinoma (MTC) and/or pheochromocytoma. The remaining 15 RET mutation carriers did not exhibit CLA; of these, one presented with MTC and pheochromocytoma, nine with MTC only, two with elevated serum calcitonin and three younger subjects with normal serum calcitonin levels. This family’s clinical data revealed a later diagnosis of MTC (mean age, 45.9 (range: 23–73) years), a lower penetrance of pheochromocytoma (2/17, 11.8%) and CLA (1/17, 5.9%). However, no hyperparathyroidism and Hirschsprung disease were reported in this family.

SUMMARY AND CONCLUSIONS

This is the first description of a family with MEN 2A-related CLA due to a germline RET C611Y mutation, which might exhibit a novel and diversified genotype–phenotype spectrum in MEN 2A.

Genotypic characteristics and their association with phenotypic characteristics of hereditary medullary thyroid carcinoma in Korea

BACKGROUND

Hereditary medullary thyroid carcinoma can present as a part of multiple endocrine neoplasia syndrome by rearranged during transfection gene mutation. We evaluated the prevalence of rearranged during transfection gene mutation in patients who have medullary thyroid carcinoma and the correlations of genotype with medullary thyroid carcinoma, pheochromocytoma, and hyperparathyroidism according to the revised American Thyroid Association risk level.

METHODS

A total of 331 patients were diagnosed with medullary thyroid carcinoma, 172 of whom were tested for the rearranged during transfection germline mutation by sequencing of exon 8, 10, 11, and 13-16. These patients were diagnosed during the years 1982-2012 at 2 Korean tertiary hospitals. Patients were analyzed according to the route of diagnosis (screened versus index cases) or the mutational site of rearranged during transfection gene (the American Thyroid Association risk group).

RESULTS

Rearranged during transfection mutation was found in 23.8% of patients tested, showing a decreasing trend with time. The most commonly mutated codon was codon 634 (37.1%), followed by codon 918 (14.3%). rearranged during transfection-positive patients were younger than rearranged during transfection-negative patients, although no other clinicopathologic characteristics differed. Screened cases were younger and had smaller tumors than index cases. Among rearranged during transfection-positive patients, pheochromocytoma manifested in 35.1% and hyperparathyroidism in 7.0%. Notably, pheochromocytoma and hyperparathyroidism emerged at any time after the diagnosis of medullary thyroid carcinoma. The American Thyroid Association risk-group analysis demonstrated that medullary thyroid carcinoma patients in the highest risk group were younger, had larger tumors, and higher disease-specific mortality. Similar results for pheochromocytoma were found, according to the American Thyroid Association risk group, although the results were not significant.

CONCLUSIONS

Korean patients who have medullary thyroid carcinoma showed a similar distribution of rearranged during transfection gene mutation with those in Western countries. The American Thyroid Association risk classification was shown to be useful for pheochromocytoma, as well as for medullary thyroid carcinoma. Familial screening for rearranged during transfection mutation and lifelong monitoring for associated pheochromocytoma should be emphasized in hereditary medullary thyroid carcinoma.

Genetic diagnosis of a Chinese multiple endocrine neoplasia type 2A family through whole genome sequencing

Approximately 98% of patients with multiple endocrine neoplasia type 2A (MEN 2A) have an identifiable RET mutation. Prophylactic or early total thyroidectomy or pheochromocytoma/parathyroid removal in patients can be preventative or curative and has become standard management. The general strategy for RET screening on family members at risk is to sequence the most commonly affected exons and, if negative, to extend sequencing to additional exons. However, different families with MEN 2A due to the same RET mutation often have significant variability in the clinical exhibition of disease and aggressiveness of the MTC, which implies additional genetic loci exsit beyond RET coding region. Whole genome sequencing (WGS) greatly expands the breadth of screening from genes associated with a particular disease to the whole genome and, potentially, all the information that the genome contains about diseases or traits. This is presumably due to additive effect of disease modifying factors. In this study, we performed WGS on a typical Chinese MEN 2A proband and identified the pathogenic RET p.C634R mutation. We also identified several neutral variants within RET and pheochromocytoma-related genes. Moreover, we found several interesting structural variants including genetic deletions (RSPO1, OVCH2 and AP3S1, etc.) and fusion transcripts (FSIP1-BAZ2A, etc.).

The Clinical Spectrum of Multiple Endocrine Neoplasia Type 2A with Cutaneous Lichen Amyloidosis in Ethnic Han Chinese

This study systematically reviewed previous literatures and analyzed the genotype-phenotype relationship between the multiple endocrine neoplasia type 2A (MEN 2A)-cutaneous lichen amyloidosis (CLA) and RET/OSMR/IL31RA mutations. RET/OSMR/IL31RA screening was performed on 8 RET-carriers from 3 independent Chinese MEN 2A families. Besides, 51 MEN 2A-CLA patients in 116 RET carriers from literatures were clustered and analyzed. Our results indicated that almost all MEN 2A-CLA patients exhibited CLA which was located in the scapular region and carried RET mutation at codon 634. Meanwhile, we firstly described MEN 2A-CLA here in Chinese Han patient with RET p.C634F mutation.

Assessment of Depression, Anxiety, Quality of Life, and Coping in Long-Standing Multiple Endocrine Neoplasia Type 2 Patients

BACKGROUND

Data on psychological harm in multiple endocrine neoplasia type 2 (MEN2) are scarce.

OBJECTIVES

The aim of this study was to assess anxiety, depression, quality of life, and coping in long-standing MEN2 patients.

PATIENTS AND METHODS

Patients were 43 adults (age ≥18 years) with clinical and genetic diagnosis of MEN2 and long-term follow-up (10.6 ± 8.2 years; range 1-33 years). This was a cross-sectional study with qualitative and quantitative psychological assessment using semi-directed interviews and HADS, EORTC QLQ C30, and MINI-MAC scales. Adopting clinical criteria from 2015 ATA Guidelines on MEN2, biochemical cure (39%; 16/41), persistence/recurrence (61%; 25/41), and stable chronic disease (22/41) of medullary thyroid carcinoma (MTC) were scored. Pheochromocytoma affected 19 (44%) patients, with previous adrenalectomy in 17 of them.

RESULTS

Overall, anxiety (42%; mean score 11 ± 2.9; range 8-18; anxiety is defined as a score ≥8) and depression (26%; mean score 11 ± 3.8; range 8-20; depression is defined as a score ≥8) symptoms were frequent. Patients who transmitted RET mutations to a child had higher scores for weakness-discouragement/anxious preoccupation and lower scores for cognitive, emotional, and physical functioning (p < 0.05). Feelings of guilt were present in 35% of patients with mutation-positive children. Lower mean score values for depression and anxiety and higher scores for role, cognitive, and emotional functioning were noticed in 33 patients who were well-informed about their disease (p < 0.05). Fighting spirit was more frequently found in patients with multiple surgical procedures (p = 0.019) and controlled chronic adrenal insufficiency (p = 0.024). Patients with MEN2-related stress-inducing factors had lower scores for fighting spirit and cognitive functioning and higher scores for insomnia and dyspnea (p < 0.05). Eleven patients required sustained psychotherapeutic treatment. Mean global health status was relatively good in MEN2 cases (68.1 ± 22.3), and the cured group had higher physical functioning (p = 0.021).

CONCLUSIONS

Psychological distress is likely chronic in MEN2 patients. This study identified diverse MEN2-related factors (degree of information on disease, mutation-positive children, number of surgeries, comorbidities, stress-inducing factors, and cure) interfering positively or negatively with the results of the psychometrics scales. The active investigation of these factors and the applied psychological assessment protocol are useful to identify MEN2 patients requiring psychological assistance.

Distribution of RET Mutations in Multiple Endocrine Neoplasia 2 in Denmark 1994-2014: A Nationwide Study

BACKGROUND

Germline mutations of the REarranged during Transfection (RET) proto-oncogene cause multiple endocrine neoplasia 2 (MEN2). It is unclear whether the distribution of RET mutations varies among populations. The first nationwide study of the distribution of RET mutations was conducted, and the results were compared to those of other populations.

METHODS

This retrospective cohort study included 1583 patients who underwent RET gene testing in one of three centers covering all of Denmark between September 1994 and December 2014. Primary testing method was Sanger sequencing, which included exons 8-11 and 13-16. Mutations were defined according to the ARUP database July 1, 2016.

RESULTS

RET mutations were identified in 163 patients from 36 apparently unrelated families. Among the 36 families 13 (36.1%) carried mutations in codon 611, four (11.1%) in codon 618, three (8.3%) in codon 620, one (2.8%) in codon 631, six (16.7%) in codon 634, one (2.8%) in codon 790, one (2.8%) in codon 804, one (2.8%) in codon 852, one (2.8%) in codon 883, and five (13.9%) in codon 918. Among the 13 families with codon 611 mutations, 12 had the p.C611Y mutation.

CONCLUSIONS

The distribution of RET mutations in Denmark appears to differ from that of other populations. Mutations in codon 611 were the most prevalent, followed by more frequently reported mutations. This might be due to a possible founder effect for the p.C611Y mutation. However, further studies are needed to find possible explanations for the skewed mutational spectrum in Denmark.

Clinical significance of RET mutation screening in a pedigree of multiple endocrine neoplasia type 2A

The clinical characteristics and RET proto-oncogene (RET‑PO) mutation status of a patient with multiple endocrine neoplasia type 2A pedigree (MEN2A) was analyzed with the aim of preliminarily exploring the molecular mechanisms and clinical significance of the disease. Clinical characteristics of a single MEN2A patient were analyzed. Genomic DNA was extracted from the peripheral blood of the proband and 10 family members. The 21 exons of RET‑PO were PCR amplified and the amplified products were sequenced. Of the family members, 5 exhibited a C634Y (TGC→TAC) missense mutation in exon 11 of RET‑PO, among which 2 family members were screened as mutation carriers, while the others did not exhibit clinical symptoms of the mutation. The screening and analysis of RET‑PO mutations for the MEN2A proband and the family members suggests potential clinical phenotypes and enables assessment of the risk of disease development, thus providing useful information for determining the surgical timing of preventive thyroid gland removal.

Distribution of RET Mutations and Evaluation of Treatment Approaches in Hereditary Medullary Thyroid Carcinoma in Turkey

OBJECTIVE

This retrospective multicenter study, centrally conducted and supported by the Society of Endocrinology and Metabolism of Turkey, aimed to evaluate the impact of free RET proto-oncogene testing in medullary thyroid carcinoma (MTC) patients. Surgical timing, adequacy of the treatment, and frequency of prophylactic thyroidectomy (PTx) in mutation carriers were also assessed.

METHODS

Genetic testing for MTC and pheochromocytoma was conducted between July 2008 and January 2012 in 512 patients. Application forms and RET mutation analyses of these patients whose blood samples were sent from various centers around Turkey were assessed retrospectively. An evaluation form was sent to the physicians of the eligible 319 patients who had confirmed sporadic MTC, familial MTC (FMTC), multiple endocrine neoplasia type 2 (MEN2), or who were mutation carriers. Physicians were asked to give information about the surgical history, latest calcitonin levels, morbidity, mortality, genetic screening, and PTx among family members. Twenty-five centers responded by filling in the forms of 192 patients.

RESULTS

Among the 319 patients, RET mutation was detected in 71 (22.3%). Cys634Arg mutation was the most prevalent mutation (43.7%), followed by Val804Met in 18 patients (25.4%), and Cys634Tyr in 6 patients (8.5%). Among 192 MTC patients, the diagnosis was sporadic MTC in 146 (76.4%), FMTC in 14 (7.3%), MEN2A in 15 patients (7.9%), and MEN2B in one patient. The number of mutation carriers among 154 apparently sporadic MTC patients was 8 (5.2%). Ten patients were submitted to PTx out of twenty-four mutation carriers at a mean age of 35±19 years.

CONCLUSION

Turkish people have a similar RET proto-oncogene mutation distribution when compared to other Mediterranean countries. Despite free RET gene testing, the number of the PTx in Turkey is limited and relatively late in the life span of the carriers. This is mainly due to patient and family incompliance and incomplete family counselling.

Molecular diagnosis and comprehensive treatment of multiple endocrine neoplasia type 2 in Southeastern Chinese

Background

Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant inherited endocrine malignancy syndrome. Early and normative surgery is the only curative method for MEN 2-related medullary thyroid carcinoma (MTC). In patients with adrenal pheochromocytoma, cortical-sparing adrenalectomy (CSA) can be utilized to preserve adrenocortical function.

Methods

We present twenty-six of 33 MEN2 patients underwent prophylactic thyroidectomy with varying neck dissection and eight of 24 MEN2A patients with PHEO underwent adrenal-sparing surgery. Direct sequencing of entire RET exons was performed in all participants.

Results

The RET mutations (p.C634Y [n = 10], p.C634R [n = 9], p.C634F [n = 2], p.C618Y [n = 8], p.C618R [n = 3], and p.M918T [n = 1]) were confirmed in 20 symptomatic patients and identified in 13 at-risk relatives (RET carriers). Twenty-six of 33 MEN2 patients underwent thyroidectomies with neck dissections; the mean age at the time of the first thyroid surgery and the tumor diameter of the 6 RET carriers was decreased compared with 20 symptomatic patients (P < 0.001 and P = 0.007, respectively), while the disease-free survival was increased (80% vs.10%, P = 0.0001). Seven RET carriers who were declined surgery. One of 20 symptomatic patients with MTC bone metastases after surgery received vandetanib therapy for 20 months and responded well. Additionally, 8 of 24 MEN2A patients who initially had unilateral pheochromocytomas underwent CSA, 1 developed contralateral pheochromo cytomas 10 years later, then also accepted and also agreed to a CSA. None of the patients required steroid replacement therapy.

Conclusions

Based on our results, integrated RET screening and the pre-operative calcitonin level is an excellent strategy to ensure earlier diagnosis and standard thyroidectomy. CSA can be utilized to preserve adrenocortical function in patients with pheochromocytomas.

Electronic supplementary material

The online version of this article (doi:10.1186/s13053-015-0026-1) contains supplementary material, which is available to authorized users.

The rare intracellular RET mutation p.S891A in a Chinese Han family with familial medullary thyroid carcinoma

We report intracellular RET mutation in a Han Chinese pedigree with familial medullary thyroid carcinoma (FMTC). Direct sequencing of RET proto-oncogene identified a missense c.2671T greater than G (p.S891A) mutation in 6 of 14 family members. The single nucleotide polymorphisms c. 135A greater than G (p.A45A), IVS4 + 48A greater than G, c. 1296A greater than G (p.A432A), c. 2071G greater than A (p.G691S), c. 2307T greater than G (p.L769L) and a variant c. 833C greater than A (p.T278N) were also found in 6 carriers. Among 5 of the 6 carriers presented medullary thyroid carcinoma (MTC) as an isolated clinical phenotype, with elevated basal serum calcitonin (Ct). Two underwent non-normative thyroidectomy either two or four times without physician awareness or diagnosis of this disease at initial treatment, but with elevated Ct. One with elevated pre-Ct accepted total thyroidectomy (TT) with modified bilateral neck dissection (MBiND), and whose seventh posterior rib MTC metastases was confirmed 5 months after surgery. Moreover, results of two affected individuals with elevated Ct were reduced to normal after TT with MBiND or prophylactic VI compartmental dissection. However, only another carrier with the variant p.T278N had slightly elevated Ct rejected surgery and was strictly monitored. Given these case results, we suggest that screening of RET and pre-surgical Ct levels in the management of MTC patients is essential for earlier diagnosis and more normative initial treatment, that FMTC patients with cervical lymph nodes metastases may be cured by TT with MBiND, and that prophylactic VI compartmental dissection should be avoided when Ct levels are low.

Molecular epidemiology of multiple endocrine neoplasia 2: implications for RET screening in the new millenium

OBJECTIVE

Twenty years ago, the groundbreaking discovery that rearranged during transfection (RET) mutations underlie multiple endocrine neoplasia 2 (MEN2) and familial medullary thyroid cancer (FMTC) ushered in the era of personalized medicine. MEN2-associated signs, taking time to manifest, can be subtle. This study sought to clarify to what extent conventional estimates of 1:200 000-500 000 underestimate the incidence of RET mutations in the population.

DESIGN

Included in this retrospective investigation were 333 RET carriers born between 1951 and 2000 and operated on at the largest German surgical referral center (286 carriers) or elsewhere (47 carriers).

METHODS

To estimate the incidence of RET mutations, the number of RET carriers born in Germany in five decades (1951-1960, 1961-1970, 1971-1980, 1981-1990, and 1991-2000) was divided by the corresponding number of German live births.

RESULTS

Owing to improved diagnosis and capture of FMTC and MEN2 patients, minimum incidence estimates increased over time: overall from 5.0 (1951-1960) to 9.9 (1991-2000) per million live births and year (P=0.008), and by American Thyroid Association/ATA class from 1.7 to 3.7 for ATA class C (P=0.008); from 1.8 to 2.7 for ATA class A (P=0.017); from 1.5 to 2.2 for ATA class B (P=0.20); and from 0 to 1.4 for ATA class D mutations per million live births and year (P=0.008). Based on 1991-2000 incidence estimates the prevalence in Germany is ∼1:80 000 inhabitants.

CONCLUSIONS

The molecular minimum incidence estimate of ≈1:100 000 was two- to fivefold greater than conventional estimates of 1:200 000-500 000.