This longitudinal registry study assesses the clinical spectra and age-related penetrance in individuals with pheochromocytomas and paragangliomas and mutations in the SDHA, TMEM127, MAX , and SDHAF2 genes. Question What does testing for the SDHA, TMEM127, MAX , and SDHAF2 genes add to effective cancer prevention? Findings Of 972 participants in the European-American-Asian Pheochromocytoma-Paraganglioma Registry without mutations in the classic pheochromocytoma/paraganglioma susceptibility genes, 58 probands (6.0%) carried certain or likely pathogenic germline mutations that included 29 in SDHA, 20 in TMEM127, 8 in MAX , and 1 in SDHAF2 . Seven of 63 carriers (relatives and probands) with SDHA and TMEM127 (11%) had malignant pheochromocytomas or paragangliomas. Meaning Gene-informed prevention and/or early detection requires regular whole-body investigation. Importance Effective cancer prevention is based on accurate molecular diagnosis and results of genetic family screening, genotype-informed risk assessment, and tailored strategies for early diagnosis. The expanding etiology for hereditary pheochromocytomas and paragangliomas has recently included SDHA, TMEM127, MAX , and SDHAF2 as susceptibility genes. Clinical management guidelines for patients with germline mutations in these 4 newly included genes are lacking. Objective To study the clinical spectra and age-related penetrance of individuals with mutations in the SDHA, TMEM127, MAX , and SDHAF2 genes. Design, Setting, and Patients This study analyzed the prospective, longitudinally followed up European-American-Asian Pheochromocytoma-Paraganglioma Registry for prevalence of SDHA , TMEM127, MAX , and SDHAF2 germline mutation carriers from 1993 to 2016. Genetic predictive testing and clinical investigation by imaging from neck to pelvis was offered to mutation-positive registrants and their relatives to clinically characterize the pheochromocytoma/paraganglioma diseases associated with mutations of the 4 new genes. Main Outcomes and Measures Prevalence and spectra of germline mutations in the SDHA, TMEM127, MAX , and SDHAF2 genes were assessed. The clinical features of SDHA, TMEM127, MAX , and SDHAF2 disease were characterized. Results Of 972 unrelated registrants without mutations in the classic pheochromocytoma- and paraganglioma-associated genes (632 female [65.0%] and 340 male [35.0%]; age range, 8-80; mean [SD] age, 41.0 [13.3] years), 58 (6.0%) carried germline mutations of interest, including 29 SDHA, 20 TMEM127, 8 MAX , and 1 SDHAF2 . Fifty-three of 58 patients (91%) had familial, multiple, extra-adrenal, and/or malignant tumors and/or were younger than 40 years. Newly uncovered are 7 of 63 (11%) malignant pheochromocytomas and paragangliomas in SDHA and TMEM127 disease. SDHA disease occurred as early as 8 years of age. Extra-adrenal tumors occurred in 28 mutation carriers (48%) and in 23 of 29 SDHA mutation carriers (79%), particularly with head and neck paraganglioma. MAX disease occurred almost exclusively in the adrenal glands with frequently bilateral tumors. Penetrance in the largest subset, SDHA carriers, was 39% at 40 years of age and is statistically different in index patients (45%) vs mutation-carrying relatives (13%; P < .001). Conclusions and Relevance The SDHA , TMEM127, MAX, and SDHAF2 genes may contribute to hereditary pheochromocytoma and paraganglioma. Genetic testing is recommended in patients at clinically high risk if the classic genes are mutation negative. Gene-specific prevention and/or early detection requires regular, systematic whole-body investigation.