An incidental finding of pheochromocytoma in a 33-year-old patient with Lynch syndrome.

Pheochromocytoma is a catecholamine-producing neuroendocrine tumor arising from chromaffin cells of the adrenal medulla. The detection of these tumors is extremely important because they are associated with high cardiovascular morbidity and mortality. Progress in molecular genetics has revealed that up to 35% of pheochromocytomas are inhereted. Lynch syndrome (hereditary nonpolypous colorectal cancer - HNPCC) is an autosomal dominant genetic condition that is associated with a high risk of colorectal cancer or other extracolonic tumors (adenocarcinoma of endometrium, stomach, ovarian carcinoma, carcinoma of urinary tract, small intestine, brain tumors and skin cancer). Foreign medical journals are reporting an increasing number of cases on coexistence of HNPCC and neuroendocrine tumors, including pheochromocytoma. It increases the likelihood that this type of tumor could represent an additional extracolonic manifestation of Lynch syndrome.

Case Report: The Role of Molecular Analysis of the MUTYH Gene in Asymptomatic Individuals.

MUTYH-associated polyposis (MAP) is a rare hereditary condition caused by the biallelic mutation in the MUTYH gene encoding MUTYH glycosylase. This enzyme is a key member of the base excision repair (BER) pathway responsible for the repair of DNA lesions formed by reactive oxygen species (ROS). We report two cases of MAP. In case 1, a 67-year-old woman who presented with a personal history of colorectal and endometrial cancer and a family history of cancer syndromes underwent multigene panel testing that revealed a germline homozygous (biallelic) pathogenic variant c.1187G > A (p.Gly396Asp) in the MUTYH gene. Subsequent sequencing analysis performed in the offspring of the proband identified all three asymptomatic offspring as carriers of this pathogenic variant. In case 2, a 40-year-old woman with a strong family history of colorectal cancer [the proband's sister was a carrier of the pathogenic variant c.536A > G (p.Tyr179Cys) of the MUTYH gene] and renal cancer underwent sequencing analysis of the MUTYH gene. The pathogenic heterozygous (monoallelic) variant c.536A > G (p.Tyr179Cys) of the MUTYH gene was identified in the proband. We found another pathogenic variant of the MUTYH gene-heterozygous (monoallelic) mutation c.1187G > A (p.Gly396Asp) in the genome of the proband's husband. Molecular analysis of their offspring revealed that they are compound heterozygotes for MUTYH pathogenic variants c.536A > G (p.Tyr179Cys)/c.1187G > A (p.Gly396Asp). This paper shows the importance of genetic testing of asymptomatic relatives of the proband to ensure an early surveillance and management of individuals positive for pathogenic variant (s) in the MUTYH gene.