Abstract
BackgroundGermline 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.MethodsTargeted 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.ResultsNineteen 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.ConclusionsThese 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.
Highlights
Germline RET mutations and variants are involved in development of multiple endocrine neoplasia type 2 (MEN2)
Multiple endocrine neoplasia type 2 (MEN2) is a neuroendocrine cancer syndrome characterized by the propensity to develop medullary thyroid carcinoma (MTC) with or without pheochromocytoma (PHEO), hyperparathyroidism (HPTH), and extra-endocrine features, such as Hirschsprung’s disease (HD) or cutaneous lichen amyloidosis (CLA) [1]
Most MEN2 cases are caused by germline gain-of-function mutations of the RET proto-oncogene (OMIM 164761), except for two families who reportedly had germline mutations in ESR2 or MET that predisposed them to MTC [1,2,3]
Summary
Germline RET mutations and variants are involved in development of multiple endocrine neoplasia type 2 (MEN2). The identification of RET mutations as the cause of MEN2 has significantly changed MEN2 disease management, including disease prevention, risk prediction, early diagnosis, and personalized treatment of MEN2-specific tumors. Together, these approaches represent a paradigm of precision medicine [1, 4,5,6,7,8,9]. These issues suggest the need for analysis of potential modifying factors, including the entire RET coding region, and an individualized strategy for clinical management of MEN2 should be considered [1, 19, 29, 34, 37, 38]
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