HaoTian Huang ¹ Jianwei Li ² Kun Zhang ³ Yu Tang ¹ Min Zhang ⁴ Zhen Fan ⁴ Tao Wang ^5,6* Liu Yaoxia ^4*

• ¹ School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan Province, China
• ² Department of Endocrinology and Metabolism, West China School of Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan Province, China
• ³ School of Biological Sciences and Technology, Chengdu Medical College, Chengdu, Sichuan, China
• ⁴ Department of Geriatric Endocrinology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan Province, China
• ⁵ Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, Sichuan Province, China
• ⁶ Key Laboratory of Birth Defects and Related Diseases of Women and Children, West China Second University Hospital, Sichuan University, Chengdu, Sichuan Province, China

Multiple Endocrine Neoplasia type 1 (MEN1) is a rare genetic disease, characterized by co-occurrence of several lesions of the endocrine system.In MEN1, the pathogenic MEN1 gene mutations lead to the Abnormal expression of menin, a critical tumor suppressor protein. We here reported a case of a 14-year-old male with insulinoma and primary hyperparathyroidism. Genetic testing demonstrated a novel heterozygote variant c.587delA of MEN1, resulting in the substitution of the 196th amino acid, changing from glutamic acid to glycine, followed by a frameshift translation of 33 amino acids. An identical variant was identified in the proband's father, who was further diagnosed with hyperparathyroidism. To the best of our knowledge, this is the first report of MEN1 syndrome caused by the c.587delA MEN1 variant. Observations indicated that, despite sharing the same MEN1 gene change, family members exhibited diverse clinical phenotypes. This underscored the presence of genetic anticipation within the familial context.