Genetic Mutation Screening in an Italian Cohort of Nonsyndromic Pheochromocytoma/Paraganglioma Patients

Abstract

To assess the prevalence of genetic mutations in nonsyndromic pheochromocytoma/paraganglioma (PHEO/PGL) patients we have performed a systematic search for mutations in the succinate dehydrogenase (SDH) B, C, and D subunits, von Hippel-Lindau (VHL), and RET genes by direct bidirectional sequencing. Patients were selected from the medical records of hypertension centers. After exclusion of syndromic patients, 45 patients with familial (F+, n = 3) and sporadic (F−, n = 42) cases of isolated PHEO/PGL were considered. They included 35 patients with PHEO, 7 with PGL, and 3 with head/neck PGL (hnPGL). Three patients with PHEO (2F−, 1F+) presented VHL mutations (P86A, G93C, and R167W), six with PGL (4F−, 2F+) were positive for SDH or VHL mutations (SDHB R230G in two patients, SDHB S8F, R46Q, R90Q, and VHL P81L in one subject each), and one with hnPGL carried the SDHD 348-351delGACT mutation. We have also detected missense (SDHB S163P, SDHD H50R and G12S), synonymous (SDHB A6A, SDHD S68S), and intronic mutations that have been considered nonpathological polymorphic variants. No mutation was found in SDHC or RET genes. Our data indicate that germline mutations of VHL and SDH subunits are not infrequent in familial as well as in sporadic cases of nonsyndromic PHEO/PGL (overall, 12 of 45 probands, 22%). Accordingly, screening for such mutations seems to be justified. However, a more precise characterization of the functional relevance of any observed sequence variant and of other genetic and environmental determinants of neoplastic transformation is essential in order to plan appropriate protocols for family screening and follow-up.

High prevalence of SDHB mutations in head and neck paraganglioma in Belgium

“…Admittedly however, the ratio between adrenal and extra-adrenal tumours observed in patients with pheochromocytoma/paraganglioma (83 vs. 17%) was in agreement with previous studies [9]. Finally, the functional character of the H50R (SDHD) [7,30,31] and S163P (SDHB) [22,32,33] substitutions remains debated. Nevertheless, exclusion of patients harbouring these genetic changes would not significantly modify our main finding, that is, a more than twofold higher prevalence of SDHB vs. SDHD mutations in patients with head and neck paragangliomas (27 vs. 13%).…”

Clinical and molecular progress in hereditary paraganglioma

“…Among non-syndromic familial PCs without evidence of HNPs, SDHB and SDHD mutations were identified in 8.5% and 8.5% of 12 families from UK 12. Among non-syndromic and non-familial PCs, SDHB and SDHD mutations were identified in 4% and 4% of 271 cases in an international collection16; 7% and 1% of 258 patients from France17; 4% and 8% of 26 cases from The Netherlands18; 12.5% and 0% of 34 patients from Italy19; and 6% and 6% of 17 cases from Japan 20. Importantly, SDHC mutations appear to be rare in PCs 21 22.…”

Methylation of the p16INK4A promoter is associated with malignant behavior in abdominal extra-adrenal paragangliomas but not pheochromocytomas

“…All exons of the SDHB gene were sequenced using previously published primers (Benn et al 2003, Castellano et al 2006Supplementary Table 2). Initial PCR was performed using a 25 ml master mix containing 12.5 ng DNA, one unit of AmpliTac Gold, 2.5 ml PCRbuffer II, 200 mM MgCl 2 (reagents from Applied Biosystems), 200 nM of each primer, and 80 nM of each dNTP.…”