RET codon 609 mutations: a contribution for better clinical managing

From Circulating Tumor Cells to Mirna: New Challenges in the Diagnosis and Prognosis of Medullary Thyroid Cancer

Medullary thyroid carcinoma (MTC) is a malignant tumor that arises from parafollicular C cells, which are responsible for producing calcitonin. The majority (75%) of MTC cases are sporadic forms, while the remaining (25%) have a hereditary component. In these hereditary cases, MTC can occur in conjunction with other endocrine disorders (i.e., pheochromocytoma) or as an isolated condition known as familial medullary thyroid carcinoma. The primary genetic mutation associated with the development of MTC, regardless of its hereditary or sporadic nature, is a point mutation in the RET gene. Evaluation of serum calcitonin levels represents the most reliable and sensitive marker for both the initial diagnosis and the postsurgical monitoring of MTC. Unfortunately, most patients do not achieve normalization of postsurgical serum calcitonin (CT) levels after surgery. Therefore, there is a need to find new biomarkers to be used with serum CT in order to increase test sensitivity and specificity. In this review, we summarize the literature from 2010 to 2023 to review the role of circulating tumor cells, cell-free DNA, and miRNA and their application in diagnosis, outcome of MTC, and response to treatments.

Transcriptome Analysis Reveals High Similarities between Adult Human Cardiac Stem Cells and Neural Crest-Derived Stem Cells

For the identification of a stem cell population, the comparison of transcriptome data enables the simultaneous analysis of tens of thousands of molecular markers and thus enables the precise distinction of even closely related populations. Here, we utilized global gene expression profiling to compare two adult human stem cell populations, namely neural crest-derived inferior turbinate stem cells (ITSCs) of the nasal cavity and human cardiac stem cells (hCSCs) from the heart auricle. We detected high similarities between the transcriptomes of both stem cell populations, particularly including a range of neural crest-associated genes. However, global gene expression likewise reflected differences between the stem cell populations with regard to their niches of origin. In a broader analysis, we further identified clear similarities between ITSCs, hCSCs and other adherent stem cell populations compared to non-adherent hematopoietic progenitor cells. In summary, our observations reveal high similarities between adult human cardiac stem cells and neural crest-derived stem cells from the nasal cavity, which include a shared relation to the neural crest. The analyses provided here may help to understand underlying molecular regulators determining differences between adult human stem cell populations.

Unique association of multiple endocrine neoplasia 2A and congenital anomalies of the kidney and urinary tract in a child with a RET mutation

Pathogenic variants in the RET gene can cause isolated and multi-system diseases. We report a patient diagnosed prenatally with unilateral multicystic dysplastic kidney and genitourinary abnormality whose mother had multiple endocrine neoplasia type 2A (MEN2A). Targeted RET sequencing found the same pathogenic variant p.C618S in the child as her mother. The child is followed by paediatric nephrology for congenital anomalies of the kidney and urinary tract (CAKUT) and by endocrine oncology for surveillance for MEN2A-related endocrine tumours. While implicated in each of these conditions individually, RET variants have never been reported to cause MEN2A and CAKUT together. This child’s family history prompted RET sequencing, resulting in presymptomatic, personalised care for MEN2A. However, this case supports the idea that genetic screening of RET (and many other genes) in patients with CAKUT may lead to molecular diagnoses that potentially improve their health through precision care.

Disease-modifying polymorphisms and C609Y mutation of RET associated with high penetrance of phaeochromocytoma and low rate of MTC in MEN2A

Mutations of the rearranged during transfection (RET) proto-oncogene, located on chromosome 10q11.2, cause multiple endocrine neoplasia type 2A (MEN2A). Patients with mutations at the codon 609 usually exhibit a high penetrance of medullary thyroid cancer (MTC), but a sufficiently low penetrance of phaeochromocytoma that screening for this latter complication has been called to question. Patients with other RET mutations are at higher risk of younger age onset phaeochromocytoma if they also possess other RET polymorphisms (L769L, S836S, G691S and S904S), but there are no similar data for patients with 609 mutations. We investigated the unusual phenotypic presentation in a family with MEN2A due to a C609Y mutation in RET. Sanger sequencing of the entire RET-coding region and exon-intron boundaries was performed. Five family members were C609Y mutation positive: 3/5 initially presented with phaeochromocytoma, but only 1/5 had MTC. The index case aged 73 years had no evidence of MTC, but presented with phaeochromocytoma. Family members also possessed the G691S and S904S RET polymorphisms. We illustrate a high penetrance of phaeochromocytoma and low penetrance of MTC in patients with a RET C609Y mutation and polymorphisms G691S and S904S. These data highlight the need for life-long screening for the complications of MEN2A in these patients and support the role for the screening of RET polymorphisms for the purposes of risk stratification.

LEARNING POINTS

C609Y RET mutations may be associated with a life-long risk of phaeochromocytoma indicating the importance of life-long screening for this condition in patients with MEN2A.C609Y RET mutations may be associated with a lower risk of MTC than often quoted, questioning the need for early prophylactic thyroid surgery discussion at the age of 5 years.There may be a role for the routine screening of RET polymorphisms, and this is greatly facilitated by the increasing ease of access to next-generation sequencing.

Hereditary Pheochromocytoma

INTRODUCTION

Pheochromocytomas (PHEO) and paragangliomas (PGL) are rare neuroendocrine tumors with an estimated occurrence of 2 to 5 patients per million per year and an incidence of about 1 per 100 000 in the general population. These tumors may arise sporadically or be associated to various syndromes, namely multiple endocrine neoplasia type 2, neurofibromatosis type 1, Von Hippel-Lindau syndrome, and hereditary paraganglioma-pheochromocytoma syndromes.

OBJECTIVES

This article aims to review the current epidemiology, pathogenesis, clinical presentation, and genetic aspects of syndromes associated with hereditary PHEO/PGL.

METHODS

The literature research, conducted at PubMed database, included review articles, published from February 2009 to February 2014, written in English or Portuguese, using as query: "Hereditary AND Pheochromocytoma."

CONCLUSION

These tumors can be part of a myriad hereditary conditions that are not yet fully understood. Nevertheless, important systemic symptoms and even fatal outcomes can occur. Knowledge of these hereditary conditions can ensure a more efficient detection, treatment, and even prevention of these neuroectodermal tumors, thus new tests and studies should be conducted.

A differential diagnosis of inherited endocrine tumors and their tumor counterparts

Inherited endocrine tumors have been increasingly recognized in clinical practice, although some difficulties still exist in differentiating these conditions from their sporadic endocrine tumor counterparts. Here, we list the 12 main topics that could add helpful information and clues for performing an early differential diagnosis to distinguish between these conditions. The early diagnosis of patients with inherited endocrine tumors may be performed either clinically or by mutation analysis in at-risk individuals. Early detection usually has a large impact in tumor management, allowing preventive clinical or surgical therapy in most cases. Advice for the clinical and surgical management of inherited endocrine tumors is also discussed. In addition, recent clinical and genetic advances for 17 different forms of inherited endocrine tumors are briefly reviewed.