Clinical Presentation and Penetrance of Pheochromocytoma/Paraganglioma Syndromes

Context: The identification of mutations in genes encoding peptides of succinate dehydrogenase (SDH) in pheochromocytoma/paraganglioma syndromes has necessitated clear elucidation of genotype-phenotype associations. Objective: Our objective was to determine genotype-phenotype associations in a cohort of patients with pheochromocytoma/paraganglioma syndromes and succinate dehydrogenase subunit B (SDHB) or subunit D (SDHD) mutations. Design, Setting, and Participants: The International SDH Consortium studied 116 individuals (83 affected and 33 clinically unaffected) from 62 families with pheochromocytoma/paraganglioma syndromes and SDHB or SDHD mutations. Clinical data were collected between August 2003 and September 2004 from tertiary referral centers in Australia, France, New Zealand, Germany, United States, Canada, and Scotland. Main Outcome Measures: Data were collected on patients with pheochromocytomas and/or paragangliomas with respect to onset of disease, diagnosis, genetic testing, surgery, pathology,anddisease progression. Clinical features were evaluated for evidence of genotype-phenotype associations, and penetrance was determined. Results: SDHB mutation carriers were more likely than SDHD mutation carriers to develop extraadrenal pheochromocytomas and malignant disease, whereasSDHDmutation carriers had a greater propensity to develop head and neck paragangliomas and multiple tumors. For the index cases, there was no difference between 43SDHBand 19SDHDmutation carriers in the time to first diagnosis (34 vs. 28 yr, respectively; P = 0.3). However, when all mutation carriers were included (n = 112), the estimated agerelated penetrance was different for SDHB vs. SDHD mutation carriers (P = 0.008). Conclusions: Forclinical follow-up,featuresofSDHBmutation-associated disease include a later age of onset, extraadrenal (abdominal or thoracic) tumors, and a higher rate of malignancy. In contrast, SDHD mutation carriers, in addition to head and neck paragangliomas, should be observed for multifocal tumors, infrequent malignancy, and the possibility of extraadrenal pheochromocytoma. Copyright © 2006 by The Endocrine Society.