H-RAS Mutations Are Restricted to Sporadic Pheochromocytomas Lacking Specific Clinical or Pathological Features: Data From a Multi-Institutional Series

Context: Somatic or germline mutations in up to 15 disease-causative genes are detectable in up to 50% of patients with pheochromocytoma (PCC) and paraganglioma (PGL). Very recently, somatic H-RAS mutations were identified by exome sequencing in approximately 7% in sporadic PCCs and PGLs, in association with male sex and benign behavior. Objective: To explore the prevalence of RAS mutations in a cohort of 271 PCC and PGL from a European registry and to compare the genotype with clinical and pathological characteristics of potential clinical interest. Setting and Design: Genetic screening for hotspot mutations in H-, N-, and K-RAS genes was performed by means of Sanger sequencing or pyrosequencing methods on tumor DNA in a series of patients with (n = 107) or without (n = 164) germline or somatic PCC/PGL-related gene mutations. Results: Overall, H-RAS mutations were detected in 5.2% of cases (14/271), which were confined to sporadic PCCs resulting in a prevalence of 10% (14/140) in this cohort. In contrast, no mutations were found in PCC with PCC/PGL-related gene mutations (0/76) or in PGL (0/55) harboring or not mutations in PCC/PGL susceptibility genes. In this large series, H-RAS mutations in PCCs lacked any significant correlation with pathological or basic clinical endpoints. Conclusions: Somatic H-RAS mutations are restricted to a relevant proportion of sporadic PCC. These findings provide the basis to study potential H-RAS-dependent correlations with long-term outcome data.