Testing for germline mutations in sporadic pheochromocytoma/paraganglioma: a systematic review

BackgroundThe presence of germline mutations in sporadic pheochromocytomas and paragangliomas (SPPs) may change the clinical management of both index patients and their family members. However, the frequency of germline mutations in SPPs is unknown. ObjectiveTo describe the frequency of germline mutations in SPPs and to determine the value of testing index patients and their family members for these mutations. MethodsWe searched databases through June 2012 for observational studies of patients with SPPs who underwent germline genetic testing. The criteria used to define sporadic tumours were (i) the absence of a family history of PCC/PG, (ii) the absence of syndromic features, (iii) the absence of bilateral disease and (iv) the absence of metastatic disease. ResultsWe included 31 studies including 5031 patients (mean age 44). These patients received tests for any of these ten mutations: SDHAF2, RET, SDHD, SDHB, SDHC, VHL, TMEM127, MAX, Isocitrate Dehydrogenase Mutation (IDH) and NF1. The overall frequency of germline mutation in SPP was 551 of 5031 or 11%; when studies with patients fulfilling four criteria for sporadic tumours were used, the frequency was 171 of 1332 or 13%. The most common germline mutation was SDHB 167 of 3611 (46%). Little outcome data were available to assess the benefits of genetic testing in index cases and family members. ConclusionsThe frequency of germline mutations in SPPs is approximately 11-13% and the most common mutations affect less than 1 in 20 patients. The value of testing for germline mutations in patients with SPPs and their family members is unknown, as the balance of potential benefits and harms remains unclear.