[Extra-adrenal pheochromocytoma associated to SDHD gene mutation]

Hereditary paraganglioma/pheochromocytoma syndrome is an autosomal dominantly inherited disease caused by germline mutation of the genes encoding subunits of the mitochondrial succinate dehydrogenase (SDH) enzyme involved in the mitochondrial respiratory chain. The pathogenetic role of SDH gene mutations was first recognized in 2000. Authors present the history of a patient with extra-adrenal pheochromocytoma who represents in Hungary the first genetically confirmed case of hereditary paraganglioma/pheochromocytoma syndrome due to disease-causing mutation of the SDHD gene. Also, the authors review the progress of our knowledge about this syndrome.

A 33 years-old man was observed with hypertension, increased perspiration and palpitation. Laboratory analysis showed increased urinary catecholamine metabolite excretion, abdominal radiologic imaging revealed a retroperitoneal tumor with 3.5 cm extension located close to the abdominal aorta. After tumor resection the clinical symptoms disappeared. Histological examination of the tumor proved extra-adrenal pheochromocytoma. Although family history was unremarkable, the young age of the patient raised the possibility of a hereditary syndrome. Mutation screening using peripheral blood DNA samples of the patient indicated the presence of c.148-149 insA frameshift mutation of the SDHD gene. Genetic analysis of family members revealed the presence of the same mutation in his asymptomatic father while the mutation was not present in his mother and brother.

The presented patient represents the first case with hereditary paraganglioma/pheochromocytoma syndrome from Hungary, in whom genetic analysis identified a disease-causing mutation of the SDHD gene. Pedigree analysis was compatible with genomic imprinting which has been demonstrated in many families with this syndrome.