A new heterozygous mutation in the CDKN1B gene in a patient affected by multiple endocrine neoplasia syndrome type 4

Multiple endocrine neoplasia syndrome type 4 (MEN-4) is a rare autosomal dominant disease caused by mutation in the CDKN1B gene encoding the cell cycle regulator p27. Currently, a small number of clinical cases of patients with this pathology are known. Patterns of genotype-phenotype correlations in patients with CDKN1B mutations remains controversial and requires additional clarification. MEN-4 affects the same organs as MEN-1, however, the age of manifestation and the course of the disease may differ. We present the clinical case of a patient with MEN-4 with a new frame shift mutation in the CDKN1B gene caused PHPT with multiple parathyroid gland pathology and prolactin-secreting pituitary microadenoma. The first component of the disease diagnosed at the age of 37 was prolactinoma. Later, a visceral form of PHPT with isolated kidney complication was revealed. The patient has got the necessary treatment of the identified pathologies with satisfactory results. During a comprehensive examination, the involvement of other endocrine organs was not revealed. The limited number of case reports of patients with mutations in the CDKN1B gene currently does not allow us to determine the patterns of this syndrome’s course, and therefore a detailed description of the disease’s clinical presentation in a patient with a newly identified mutation makes a significant contribution to the study of this pathology.