THU081 Differences In Circulating Microrna Levels In Genetically Confirmed Multiple Endocrine Neoplasia Type 1 And Multiple Endocrine Neoplasia Type 1 Phenocopies As Assessed By Next Generation Sequencing

Disclosure: D.A. Trukhina: Grant Recipient; Self; Russian Science Foundation (project N 19-15-00398-П). E.O. Mamedova: Grant Recipient; Self; Russian Science Foundation (project N 19-15-00398-П). P.A. Koshkin: Grant Recipient; Self; Russian Science Foundation (project N 19-15-00398-П). A.G. Nikitin: Grant Recipient; Self; Russian Science Foundation (project N 19-15-00398-П). G.A. Melnichenko: Grant Recipient; Self; Russian Science Foundation (project N 19-15-00398-П). Z.E. Belaya: Grant Recipient; Self; Russian Science Foundation (project N 19-15-00398-П). Multiple endocrine neoplasia type 1 (MEN1) is a rare disease caused by mutations in the MEN1 gene encoding the menin protein (gMEN1). This syndrome is characterized by the occurrence of parathyroid tumors, gastroenteropancreatic neuroendocrine tumors (GEP-NETs), pituitary adenomas, as well as other endocrine and non-endocrine tumors. Patients with MEN1 phenotype without MEN1 mutations are considered MEN1 phenocopies (phMEN1). It has not been studied whether the development of MEN1 phenocopies is determined by epigenetic changes, particularly by altered microRNA expression, which can affect menin. Materials & methods Single-center, case-control study: assessment of plasma microRNA expression in patients with gMEN1, phMEN1 and healthy controls. Morning plasma samples were collected from fasting patients and gender-matched controls and stored at –80C. Total RNA isolation was performed using miRNeasy Mini Kit with QIAcube. The libraries were prepared by the QIAseq miRNA Library Kit. Circulating miRNA sequencing was performed on Illumina NextSeq 500. Subsequent data processing was performed using DESeq2 bioinformatics algorithm. Results We enrolled 24 patients with gMEN1 and 12 patients with phMEN1, along with 12 gender-matched controls. The median age of gMEN1 patients was 39 [35; 46]; in phMEN1 — 59 [51;60]; control — 59 [51.5; 62.5]. The gMEN1 group differed in age (p50 counts), the second group — moderate (10–50), the third group — the lowest (